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PPMS TTO Manual - Materials Research Laboratory at UCSB

1. eese eee nente enne 5 7 Resistivity Excitation Parameters for Continuous Mode Measurements eee 5 8 Status Associated with Bits of General System Status Field sese B 1 TTO Stat s COMES se nete iit rper n e ea Pede eed e e t eee sees B 3 TTO Sample C nnections ird doo eto em e ended o et eet e C 2 PPMS Thermal Transport Option User s Manual V P RE FA C E Contents and Conventions P 1 Introduction This preface contains the following information e Section P2 discusses the overall scope e Section P 4 illustrates and describes of the manual conventions that appear in the manual e Section P 3 briefly summarizes the contents of the manual P 2 Scope of the Manual This manual discusses the Thermal Transport option TTO for the Physical Property Measurement System PPMS This manual explains how to use the TTO system and it explains the theory of operation for TTO This manual describes the hardware and software that are unique to TTO and it includes maintenance and troubleshooting information For detailed information about the PPMS MultiVu software which is the parent software application running the PPMS refer to the Physical Property Measurement System PPMS MultiVu Application User s Manual P 3 Contents of the Manual e Chapter 1 presents an overview of the e Chapter 5 explains how to take measure TTO system and of the TTO theory of ments with TTO and describes the
2. 1 PUCK MOUNTING STATION ASSY 4084 600 CONNECTOR EXTRACTOR 4084 584 CERNOX SHOE ASSY TESTED 4084 580T HEATER SHOE ASSY 4084 585 SCREWS METRIC M1 2 4084 591 Ni STANDARD SAMPLE ASSY 4084 611 CALIBRATION FIXTURE ASSY 4084 595 Chapter 2 Hardware 22 3 2 2 4 Section 2 2 Thermal Transport Hardware Nickel Calibration Samples Two samples of nickel metal grade 201 are Table 2 1 Recommended Sample supplied in the user s kit in the form of thin plates Parameters for Nickel Calibration stamped in a four probe comb configuration see Samples Section 4 3 and can be used as references and calibration verification for all standard thermal transport measurements thermal conductivity K Cross sectional area 0 32 mm Seebeck coefficient a and electrical resistivity p Variations in the geometrical factor A I on the order of 5 are to be expected from sample to Surface area 35 mm sample which will be reflected in the x and p data Table 2 1 lists standard dimensions for the Ni standard It is also recommended that the Ni standard be mounted on the puck in the vertical configuration in order to avoid touching the radiation shield PARAMETER VALUE Length 8 3 mm Emissivity 0 5 WaveROM EPROM The DSP board that is used with the ACMS and ACT options contains a square ROM chip that holds waveform tables for the excitation current generated by the DSP The TTO system require
3. 1 7 1 5 2 Thermal and Electrical Circuit esses enne enne ener neen eren en nnne 1 7 1 5 3 Software Models oer eee rte rero e teatros e eem eese rU Dre mr e strands 1 8 1 5 4 Bstim ng Errors am tlie Data orem RT REPE D IEEE De iE TRU aa EEE 1 9 1 5 5 Correcting for Heat Losse reoi en RO TR EE DR ER RU EPOD 1 11 1 5 6 Correcting for Seebeck Coefficient of Manganin Leadis esee 1 11 1 6 Start up Checklist for Secondary Installation esee eee 1 11 CHAPTER 2 ISEWILETERRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRERRRRRRRRREMMMMMMEMEMKMKMK FE5EZ NHASSSRNIERIMMMMM 2 1 2 1 Intr d ction T 2 1 2 2 Thermal Transport HardWare sss 5s eerte rere e ee dep ER ERI SERERE UNE CREER SEE SEEN H ERE TUS Cree dapes 2 1 2 2 1 Thermal Transport Sample Puck 4 eene eer tee P ERR E EE E NE eere RENE ERR VY eR eR RES 2 2 2 2 2 User S KI RR n EIE FBNSEE EE UAR R I EP REV EUER QU Ve eR E eee E NEAR ERR TN 2 3 2 2 3 Nickel Calibration Samples ode Dente tete eei i ute Deere eeu Eee UR RE 2 5 22 4 WayeROM EPROM 2e TER n E ere resta tbe ree te eco Prat ab CERE tas 2 5 2 24 T Replacing the WaveROM Chip rhe ee e teat beers p PORE S Deere sehe er eoe uten 2 6 2 2 5 Thermal Transport Connection Cable eetere eive N eae E E ener EEEE enne nenne enne 2 6 2 2 6 User Bridge Board oce teer HT A re yb Fest Le dre eR RU REED RU E Yee e EXER do de eie oer
4. Temp Rise K Rise in temperature of the hot thermometer due to the applied heat pulse Should be close to user requested value set in Thermal tab oo Htr Power W e ONE REPLEERNEEN heater power in watts Heater Power Heater Power W Actual heater power 0000000000 heater power Rad Loss W Estimated power loss due only to radiation from sample See Section 1 5 5 Res Drive mA Current drive used for resistivity measurement Map 20 29 User designated data items Reserved for hot and cold sample Map 21 22 thermometers Rotator probes are not currently available for use with TTO 3 12 PPMS Thermal Transport Option User s Manual Quantum Design Chapter 3 Section 3 4 Software Thermal Transport Data Files 3 4 4 Format of Raw Data Files If the Capture Raw Data check box is selected in the Data File tab in the Thermal Transport control center Figure 3 3 raw measurement data is recorded to a data file For thermal conductivity and Seebeck coefficient measurements raw data also includes results from the thermal model For resistivity measurements raw data includes the excitation current and signal voltage Table 3 3 Fields in Thermal Transport Raw File ITEM DEFINITION System status and TTO software comments Time Stamp Time of measurement data point expressed in minutes or seconds and as an absolute time or relative to the start time of the data file T Hot K Temperature of sample hot thermometer
5. Waveform tab 3 4 WaveROM EPROM illustration on AC board 2 5 part number 1 2 replacing 2 6 upgraded version for Thermal Transport option 2 1 2 5 Wizards calibration 2 9 2 10 3 5 installation 3 3 5 3 Index 3
6. Connect Leads to the Sample Four leads must always be connected to any sample that will be measured with the TTO system a source current I and heat source two probes Thot V and T oiqg V and a sink current I and heat sink Leads are designed to mount permanently on the sample and offer high thermal conductance and electrical conductivity from the gold plated copper shoes to the sample Complete the following steps to connect leads to the sample 1 Prepare a sample in which the estimated room temperature thermal conductance is K 10 mW K for best results stay between 5 mW K and 15 mW K Decide whether to attach the leads in a two probe or four probe configuration Refer to Section 4 3 for more information For leads both bars and disks of gold plated copper are included in the sample mounting kit If you use another lead material it must have high thermal conductance yet be smaller than 0 5 mm 020 inch in diameter in order to fit in the shoe assemblies In addition it must have good electrical conductivity and be free of insulating oxidized surfaces where contact is made to the shoe assemblies or to the sample Decide which epoxy material silver filled or insulating is appropriate to the measurements you will take Refer to Section 4 2 2 for more information Prepare the leads by bending them to shape so that they fit snugly around the sample to maximize thermal conductance at the contact to the sample Mou
7. T Cold K Temperature of sample cold thermometer Quantum Design PPMS Thermal Transport Option User s Manual 3 13 Section 3 5 Chapter 3 Data Examination Software 3 5 3 14 Data Examination To examine the current TTO dat data file in PPMS MultiVu you can select the View button in the Data File tab in the control center If raw data is also being saved the raw file can be opened by using the File Open menu command The Physical Property Measurement System PPMS MultiVu Application User s Manual discusses the graphing and data viewing formats in detail The ExportData exe program located in the QDPPMS Tools directory can be used to export specific columns and portions of the data file header from any data file Errors encountered by the PPMS during TTO data acquisition are listed in the TTO status log see Section 3 3 3 In addition an Error Count dialog is opened if any individual TTO measurement fails A running total of the error counts is displayed and brief one line descriptions of the last three errors are listed in the window If this dialog is closed it can be accessed by using the View TTO Error Count menu command Selecting the Reset button will zero the displayed error totals for each measurement but will not affect the TTO log file ue Seebeck Seins Figure of Conductivity Coefficient Resistivity Merit zT Er 0 0 Figure 3 12 Error Count Dialog Box PPMS Thermal Transport Option
8. The 14 pin Lemo connector plugs into the gray color coded port on the PPMS probe head The connector labeled J1 P1 User Bridge plugs into the P1 User Bridge port on the Model 6000 The connector labeled J2 P1 Sample Current Out plugs into the P1 Sample Current Out port on the Model 7100 The connector labeled J5 P5 Sample Voltage In plugs into the P5 Sample Voltage In port on the Model 7100 5 RRES h REN VE AS d oF J2 P1 SAMPLE PROBE ER lcurrent OUT 170 170 jg JERS SAMPLE VOLTAGE TN CH JN TTo Figure 2 5 Thermal Transport Connection Cable 2 6 PPMS Thermal Transport Option User s Manual Quantum Design Chapter 2 Section 2 3 Hardware ACT Hardware 2 2 6 User Bridge Board The TTO system employs the user bridge board to read the hot and cold Cernox thermometer shoe assemblies that are on the sample The user bridge board is in the Model 6000 see Figure 2 4 Detailed information about the user bridge board is in the Physical Property Measurement System Resistivity Option User s Manual 2 3 ACT Hardware The TTO system uses hardware for the AC Transport Measurement System ACT option in order to generate the heat pulse and read back the sample thermal voltages in the thermal
9. gt A pointing hand and the word NOTE introduce a supplementary note NOTE CAUTION Cautionary notes are preceded with the word CAUTION This signals conditions that could result in loss of information or damage to your equipment WARNING Warnings are preceded with the word WARNING This signals conditions that could result in bodily harm or loss of life Vill PPMS Thermal Transport Option User s Manual Quantum Design C H A P T E R 1 Introduction 1 1 1 2 Introduction This chapter contains the following information e Section 1 2 presents an overview of e Section 1 5 explains the TTO system s the TTO system theory of operation e Section 1 3 describes the TTO system e Section 1 6 contains the start up checklist measurement modes for secondary installation of the TTO e Section 1 4 explains how the TTO system measures thermal properties Overview of the Thermal Transport Option The Quantum Design Thermal Transport option TTO for the Physical Property Measurement System PPMS enables measurements of thermal properties including thermal conductivity and Seebeck coefficient also called the thermopower a for sample materials over the entire temperature and magnetic field range of the PPMS The TTO system measures thermal conductivity or the ability of a material to conduct heat by monitoring the temperature drop along the sample as a known amount of heat passes through the sample TTO measures the thermoelectric
10. 14 34 5 7 Voltage sample V 14 2 4 6 8 Ground 5 shell 13 E SAMPLE PUCK BOTTOM GRAY LEMO CONNECTOR LAE E P5 SAMPLE VOLTAGE IN MODEL 7100 P SAMPLE CURRENT OUT MODEL 7100 SAMPLE INTERFACE PROBE HEAD BOTTOM OF PROBE 131211109 87 65432 1 P1 USER BRIDGE PORT OOOOOOOOOOOOO MODEL 6000 OOOOOOOOOOOO 252423222120191817161514 Figure C 1 Illustration of TTO Sample Connections Showing Hardware Ports C 2 PPMS Thermal Transport Option User s Manual Quantum Design Appendix C Pinout Tables Quantum Design Section C 2 Thermal Transport Pinouts FINAL PIN OUT DIAGRAM RED PIN BETWEEN CONNECTORS PCB 4084 575 BLUE Figure C 2 Top View of Pinout of Connector Sockets on Thermal Transport Sample Puck PPMS Thermal Transport Option User s Manual References Maldonado O 1992 Pulse method for simultaneous measurement of electric thermopower and heat conductivity at low temperatures Cryogenics 32 10 908 12 Quantum Design 2001 Physical Property Measurement System AC Transport Option User s Manual 2000 Physical Property Measurement System Cryopump High Vacuum Option User s Manual 2000 Physical Property Measurement System PPMS MultiVu Application User s Manual 1999 Physical Property Measurement System Resistivity Option User s Manual 2000 Physical Property Measurement System Turbo Pump High Vacuum Option User s Manual Weast R C 198
11. Advanced Tab eese ener enne nrenne nenne tnnn nee nre nn enne 3 5 Figure 3 7 Settings Tab in Thermal Transport Measurement Dialog Box eene 3 6 Figure 3 8 Thermal Tab in Thermal Transport Measurement Dialog Box eese 3 6 Figure 3 9 Resistivity Tab in Thermal Transport Measurement Dialog Box eee 3 7 Figure 3 10 Mode Tab in Thermal Transport Measurement Dialog Box eese 3 8 Figure 3 11 Advanced Tab in Thermal Transport Measurement Dialog Box eee 3 8 Figure 3 12 Error Count Dialog BOX ienee reolas aiara b e RE Tere CERO EEIE a Sa 3 14 Figure 4 1 Examples of Leads Mounted in Two Probe Configuration eese eene 4 4 Figure 4 2 Example of Leads Mounted in Four Probe Configuration eese eene 4 5 Figure 5 1 Thermal Tab in Thermal Transport Measurement Dialog Box eese 5 6 Figure 5 2 Resistivity Tab in Thermal Transport Measurement Dialog Box eee 5 8 Figure 7 1 Puck Adjustment Tool cccccsscssscsscesecosscossenscensesscosseessesscesseseeconscosscossenscensenseonsesssessesssesseesnscnnesnes 7 1 Figure A 1 Thermal Transport Option Connection Diagram eeeeeeeeeeeeeeereen eere eere nennen A 2 Figure C 1 Illustration of TTO Sample Connections Showing Hardware Ports eene C 2 Figure C 2 Top View of Pinout of Connector S
12. Seebeck effect as an electrical voltage drop that accompanies a temperature drop across certain materials The TTO system can perform these two measurements simultaneously by monitoring both the temperature and voltage drop across a sample as a heat pulse is applied to one end The system can also measure electrical resistivity p by using the standard four probe resistivity provided by the PPMS AC Transport Measurement System ACT option Model P600 All three measurement types are essential in order to assess the so called thermoelectric figure of merit ZT a T kp which is the quantity of main interest if you are investigating thermoelectric materials While the measurements taken with the TTO system are quite elementary in principle they have eluded commercialization because the data was typically very error prone time consuming and laborious due for example to problems in controlling heat flow and accurately measuring small temperature differentials in a convenient manner The TTO system has solved or greatly reduced many of these experimental complications TTO uses convenient sample mounting small and highly accurate Cernox chip thermometers and sophisticated software that dynamically models an AC heat flow through the sample and corrects for any heat losses that occur The PPMS with the High Vacuum option Model P640 provides an ideal environment for the custom designed TTO sample puck and the ACT option Model P600 powers the s
13. a gauge of the copper contact finger positioning on the puck If the puck is not held in the socket or if it cannot fit in the socket you must set the finger position with the puck finger adjustment tool see Section 7 2 PPMS Thermal Transport Option User s Manual Quantum Design C H APTER 5 Measurements 5 1 Introduction This chapter contains the following information e Section 5 2 explains how to take e Section 5 4 discusses the TTO measurements with the TTO system measurement process e Section 5 3 discusses the measurement mode parameters 5 2 Taking Thermal Transport Measurements Ey Thermal Transport measurements can be taken only if a the Thermal Transport connection cable is plugged into the gray color coded Lemo port on the PPMS probe head and 5 the Thermal Transport option is activated in PPMS MultiVu Refer to Appendix A to install and activate the Thermal Transport option You are encouraged to use the Thermal Transport control center to perform all normal TTO system operations The automated routines in the control center help ensure that you complete the necessary procedures when you install new samples and create data files The examples of immediate mode measurements in this chapter illustrate use of the control center Quantum Design PPMS Thermal Transport Option User s Manual 5 1 Section 5 2 Chapter 5 Taking Thermal Transport Measurements Measurements 5 2 1 5 2 2 4 NOTE r ES
14. adaptive algorithm you must set the allowable ranges for thermal measurement parameters These parameters which include measurement period heater power and Seebeck voltage are set in the Thermal tab in the Thermal Transport Measurement dialog Figure 5 1 Similarly for resistivity measurements you must define the range of excitation and frequency parameters You set these parameters in the Resistivity tab in the Thermal Transport Measurement dialog Figure 5 2 e In single mode you state the style of single mode measurement along with the fixed heater power measurement period and maximum expected Seebeck voltage 5 4 PPMS Thermal Transport Option User s Manual Quantum Design Chapter 5 Measurements 5 2 8 5 2 9 Section 5 2 Taking Thermal Transport Measurements Run the Measurement 5 2 8 1 RUNNING THE MEASUREMENT INTERACTIVELY To run a thermal transport measurement interactively you select the Measure button that is at the bottom of the Thermal Transport control center Selecting the Measure button opens the Thermal Transport Measurement dialog box which you use to select the thermal properties you want to measure as well as the parameters and limits for the measurements By default dynamic continuous measurements are made using an AC technique unless you use the Mode tab Figure 3 10 to switch to steady state single measurements Refer to Section 1 3 for more information on the various modes of operation The me
15. duration of the heat pulse is obtained a nonlinear least squares fitting routine which fits the data to the empirical formula is launched AT model AT x 1 1i x exp t 1i T2 x exp t v5 11 T2 Equation 1 1 where AT represents the asymptotic temperature drop across the sample if the heater is left on indefinitely and x and v are long and short empirical time constants respectively for the sample see Figure 1 2 The fitting routine performs an exhaustive search over the space of these three parameters reducing the space iteratively until the parameter values that yield the minimum in the residual of the curve fit are identified satisfactorily Equation 1 1 1s appropriate to the data taken during the heating pulse while the data taken during the cooling pulse is simultaneously fit essentially by changing the sign of the model equation AT modeicooting A AT model heating Where A is a constant Due to long 1 8 PPMS Thermal Transport Option User s Manual Quantum Design Chapter 1 Introduction 1 5 4 Section 1 5 Theory of Operation thermal diffusion times t1 the thermal history of the sample must be accounted for in the model and this is achieved by including the remanent effects of the two previous pulses in modeling the current pulse The fitting routine for Seebeck coefficient data is similar yet it is less computationally intensive The AV vs time data is read back from the DSP buffer at the end o
16. e 2 7 23 ACT Hard Ware oe eia eaa eeraa e are a N E NE E E EENE E tecvoaseuel cusatedvsyeWveuseue hesseudsus EEE 2 7 2 3 1 Model 7100 AC Transport Controller eeeeeseeeeeeeeeeeeeee nennen nennen eene enne eene nenne 2 7 233 2 AC Board 55e cde m re ee ettet eerte eerie 2 Quantum Design PPMS Thermal Transport Option User s Manual 1 Contents Table of Contents 2 4 Migh Vacuum Hardware Hci ied et eom eee ed aterm a elie ae ani aL ERE Eire qnt 2 8 24 1 Contact Battle erre tft ere pte edet es n esee eite dte Pesca dese Meera ties 2 8 2 5 Calibrating New Shoe Assemblies eie dnte ce E E ania AS re IRR Dei rp PRU A aeS 2 9 CHAPTER 3 Software Gerona astu a Pe Ph Tae E me enone UR RR REN ERE ae Tet sabbia Rc 3 1 3 1 Introd cti n Avastin seen te eee Ry eec A pe oi ib ep lores 3 1 3 2 Overview of Thermal Transport Software eene ener enne nnen enne nnne 3 1 32 1 Measurement Units 2 2 ee eeaeee eei Deiode iem d d etes 3 2 3 3 Thermal Transport Control Center ss eronneen nennen eene enne EAEE E EEE 3 3 3 3 TL Control Center Tabs nested Oda ee ie AG aad ere ais 3 3 3 3 2 Measurement MnDU sip Het ih Resides SAL elbea eaa isa ied baci aet 3 5 3 3 2 1 Options for Advanced Users paiinitin E eie VETE e ne enne trennt testen enter nenne a enne 3 8 3 3 3 SYSTEMS talus ish sioe eene da ego posee teles ede test od Gi bc bee ii a etes 3 9 3 4 Thermal Transport Data Files sriain ienien eene enne ener nenne nnen
17. eene trennt nre EEEN Ei oes 3 10 3 4 1 Saving Raw Thermal Transport Data eese ener enne enne nennen ene nnen netten 3 10 3 42 Data File Header 2 pee eben DL aa eden tte EHE Ies e te ete wee alae 3 10 3 4 3 Format of Measurement Data Files eese teen enne nennen ene teen nennen nennen enne 3 11 3 44 Format of Raw Data Files unn aeter ideo Dm p o tre e EE rre 3 13 3 3 Data Examinations 5 ori t eeu e EHE CR km PG ERA Pe oto Qe eui ORE Maven atic 3 14 CHAPTER 4 Sample Preparation sse tte treten tette tete treten tte tete tentent tenens 4 1 4 T IntroductioB save eom e ete trt Eh ote n et etes 4 1 4 2 Sample Mounting Considerations eese ener nennen ener ennt inneren tnen retener ennt nenne 4 1 4 2 T Geometry eese e t dete epi hd o pf etd ene e e eie 4 2 42 2 Eead Mounting EpoxiIes s doge te ee o ete te i e dei eei ree e ee 4 3 4 2 2 1 Silver Filled H20E Epoxy nere apte e eee EH RD RUE TRE anes 4 3 42 22 Tra Bond 16HO01 EpOXy eta eter eroe e edet ete 4 3 4 3 Two Probe and Four Probe Lead Configurations eese nennen enne enne 4 4 4 3 1 Two Probe Lead Configuration rie ee t rte ee RC te E RE Eg e e ERES Dee BR 4 4 4 3 2 Four Probe Lead Configur tion eerte peterem be t HU RET ee ER GERE HRS EA e BR 4 5 44 Checkmg the Sample Contact acriter pete e EC PP REL HR UE RD RD RO ERREUR TREES 4 6 4 5 Using th Puck Mountng Stati n odes u
18. epoxy and allow 24 hours for epoxy bonds to cure Note that the liquid epoxy may have a grainy appearance this is normal Quantum Design PPMS Thermal Transport Option User s Manual 4 3 Section 4 3 Chapter 4 Two Probe and Four Probe Lead Configurations Sample Preparation 4 3 4 3 1 Two Probe and Four Probe Lead Configurations There are two methods of mounting the electrical thermal leads on a sample These two different methods present a trade off between convenience of mounting and accuracy of measurement Two Probe Lead Configuration The two probe lead configuration method is the most convenient because it involves attaching only two leads but this method sacrifices accuracy because heater I and Thot V share one lead while coldfoot I and T 44 V share the other lead Figure 4 1 Thus the thermal and electrical contact resistances between the leads and sample contribute to the measured quantities You should use the two probe lead configuration method only when the thermal and electrical resistances of the sample are far greater than those of the leads Examples of samples mounted in this fashion are shown in Figure 4 1 where both bar shaped and disk shaped copper leads are used T Ti Te COLDFOOT COLDFOOT Two Probe Lead Configuration Using Two Probe Lead Configuration A Disk Shaped Copper Leads B Using Bar Shaped Copper Leads Figure 4 1 Examples of Leads Mounted in Two Probe Configuration Note that the therm
19. gt Measure Type v Thermal Conductivity IV Seebeck Coefficient Electrical Resistivity Figure of Merit ZT Gener IV Save Marginal Results Discard First N Results 3 gt Next Measuremen Period 300 Power 10 1 Curent Measurement 265 45 K 70000 De Temp Field Conduct 1 222 W K m Period 74 sec Power 25 42 mw CENE Er nw Period Power m Progress Stop Pause Close Help fee CS Chapter 3 Software Settings and limits for thermal measurements thermal conductivity and Seebeck coefficient are determined in the Thermal tab Figure 3 8 These settings and limits include limits of heater period and power and expected limits of Seebeck readback voltage as well as target amplitude for the heat pulse expressed as percentage of sample temperature and target value of period ratio which is defined as measurement period divided by the time constant tav of the sample see Section 3 4 3 for more information on these quantities Any changes made in this tab are saved only if the Set button in the tab is selected A ToolTip displays hardware limits for the heater power if the cursor is placed over the panels showing the heater power limits Note that a period ratio of at least 8 is recommended because choosing a value lower than this has been shown to produce artifacts in the thermal transport measurements due to insufficient data for the software model Thermal Transp
20. measurements and to make the four probe resistivity measurement on the sample 2 3 1 Model 7100 AC Transport Controller The driver board in the Model 7100 AC Transport Controller excites the sample by receiving and amplifying the signal from the AC board s digital signal processor DSP The preamp board in the Model 7100 detects the sample signal and sends the signal back to the DSP so the DSP can process the signal The Physical Property Measurement System AC Transport Option User s Manual discusses the components and operating modes of the Model 7100 in more detail CAUTION The Model 7100 provides as much as 200 mA of current when being controlled by the TTO system Although this is lower than the hardware limit of 2 A this current can still damage samples in the current path Use only currents that can be safely handled by all hardware and samples in the circuit OUTPUT RANGE MODE MEASURE PREAMP GAIN q o q o o q o o CONSTANT VOLTAGE 2 CH2 x x10 x100 x1000 CURRENT LIMITED POWER MONITOR CURRENT VOLTAGE a MODEL 7100 zm amp AC TRANSPORT CONTROLLER Se Figure 2 6 Front Panel on Model 7100 AC Transport Controller 2 3 2 AC Board The AC board is installed in the Model 6000 PPMS Controller and is located behind the P3 Option port which is the port connecting the Model 6000 to the Model 7100 The waveROM EPROM Section 2 2 4 plugs into
21. operation measurement process e Chapter 2 discusses and illustrates the e Chapter 6 contains troubleshooting hardware used with TTO suggestions e Chapter 3 discusses the TTO software e Chapter 7 explains basic maintenance and TTO data files procedures e Chapter 4 explains how to prepare samples for TTO measurements Quantum Design PPMS Thermal Transport Option User s Manual vu Section P 4 Preface Conventions in the Manual Contents and Conventions e Appendix A explains how to install the e Appendix C contains pinout tables TTO hardware and software e Appendix B contains status codes and error messages P 4 Conventions in the Manual File menu Bold text distinguishes the names of menus options buttons and panels appearing on the PC monitor or on the Model 6000 PPMS Controller LCD screen File gt Open The gt symbol indicates that you select multiple nested software options STATUS Bold text and all CAPITAL letters distinguish the names of keys located on the front panel of the Model 6000 PPMS Controller dat The Courier font distinguishes characters you enter from the PC keyboard or from the Model 6000 PPMS Controller front panel The Courier font also distinguishes code and the names of files and directories Enter Angle brackets distinguish the names of keys located on the PC keyboard lt Alt Enter gt A plus sign connecting the names of two or more keys distinguishes keys you press simultaneously 3
22. the Set button in the tab was selected or the default values if Set has not yet been selected Table 5 1 Minimum and Maximum Parameter Limits for Continuous Mode Measurements PARAMETER FUNCTION DESCRIPTION Period Length in seconds of Minimum is 30 seconds due to limited data heater on off cycle acquisition rate of hot cold Cernox temperatures from user bridge Maximum period is 1430 seconds Only discrete values of the period are allowed period 4292 n where n is an integer n gt 2 This implies that jumps between available periods become larger as period grows Power Limits power that heater Default limits are 1 yW and 50 mW Minimum value resistor can output is limited by hardware limitations of the DAC of the Expressed in mW current source to 10 uA which translates to 0 2 yW for 2 kQ heater Maximum value is set by voltage compliance of 10 V of the current source which translates to 50 mW for 2 kQ heater continues 5 6 PPMS Thermal Transport Option User s Manual Quantum Design Chapter 5 Measurements Quantum Design Section 5 3 Measurement Mode Parameters Table 5 1 Minimum and Maximum Parameter Limits for Continuous Mode Measurements Continued voltage readback preamp PARAMETER FUNCTION DESCRIPTION Temp Rise Target value of temperature Defined as rise in Thot due to the heater divided by rise during heating average temperature during this time This parameter expre
23. the TTO User s Kit Bend the leads on the sample so that you can mount it as shown in Figure 2 9 Then mount the copper sample to the cold foot and mount the copper shoes to the sample When mounting the heater shoe make sure the copper sample does not touch the solder pad of the heater resister which could cause an electrical short Note the serial numbers of each shoe assembly Then screw the shield onto the TTO puck Unscrew the shield cap and make sure none of the copper shoes are touching any part of the puck or the shield Replace the shield cap then insert the puck into the PPMS Remove the charcoal carrier on the contact baffle assembly see Section 2 4 1 to ensure exchange gas is not cryopumped at low temperatures Place the baffle set inside the sample chamber Then purge and seal the sample chamber In the calibration wizard window check the box for the thermometers and or heaters you wish to calibrate and enter their serial numbers The default temperature range should be 1 8 to 400 K The heater parameters have been selected to optimize the signal for the 2kO heater resistors supplied Press the Start button to begin calibration which will last approximately 16 hours After calibration is complete you must make the appropriate changes to TTO initialization file TTO INI if you wish to use the newly calibrated shoe assemblies immediately See Section 3 2 Quantum Design PPMS Thermal Transport Option User s Manual 2 9 Sectio
24. the use of a sophisticated curve fitting algorithm that determines the steady state thermal properties by extrapolating from the response to a relatively short typically several minutes heat pulse Single Measurement Mode The single measurement mode is slower than continuous measurement mode because it requires that the system reach a steady state in both the heater off and on states which also implies that temperature or field slewing is unavailable The advantage of single measurement mode is that no Quantum Design PPMS Thermal Transport Option User s Manual 1 3 Section 1 3 Measurement Modes 1 4 Chapter 1 Introduction subtle curve fitting calculations are required so interpretation of the raw data is in principle more straightforward Researchers who study thermal transport properties usually employ this steady state technique because of its simplicity and robustness In either style of single measurement stability or timed described below in Table 1 4 data is first taken in the heater off state once the system settles After the user specified heater power is applied the system waits for the selected equilibrium condi tion before making the final measurement in the heater on state You can view the live AT vs time data in the Waveform tab of the Thermal Transport control center to monitor measurement progress Table 1 4 Styles for Measurements Taken in Single Measurement Mode MEASUREMENT S
25. 0 300 Hz Duration fi sec IV Constant Current Mode Low Resistance Mode C Always Autorange f Sticky Autorange Fixed Range zj Set Clear Stop Pause Close Help Figure 3 9 Resistivity Tab in Thermal Transport Measurement Dialog Box Temp 30818 kK Field 70000 Oe Conduct 1 18 44 W K m Seebeck 88 774 VK Resist zT Period 80 98 sec Power 29 8 mw Current Measuremen Period 80 38 sec Power 29 8 mw Progress pecu p Quantum Design PPMS Thermal Transport Option User s Manual Section 3 3 Chapter 3 Thermal Transport Control Center Software 3 3 2 1 OPTIONS FOR ADVANCED USERS Two more tabs the Mode tab and the Advanced tab are made visible in the Thermal Transport Measurement dialog box by clicking on the right pointing arrow that is next to the tab names at the top of the dialog box Clicking on the left pointing arrow hides the Mode and the Advanced tabs Generally these two tabs are of interest only to advanced users You use the Mode tab to select Thermal Transport Measurement lel ES T whether to take continuous Advanced 4 p r Last Measurement measurements default or CMasumModa Teng 27012 K single steady state measure Continuous Measuring Field 70000 Oe ments There are two modes C Stability to dT T jor 2 Conduct 54 436 W K m of single measurement Seebeck 50 683 uv AK stability or timed Sectio
26. 1 3 1 4 5 9 using 5 4 Software See PPMS MultiVu Thermal Transport software Status codes general PPMS B 1 B 3 Thermal Transport system B 3 Status system See Thermal Transport control center Showing system status Quantum Design Temperature calibration 2 9 ramping during measurements 5 5 system range 1 2 Thermal conductivity estimating errors 1 9 1 10 how measured 1 5 5 9 See also Thermal Transport software Models measuring 5 1 5 5 See also Measurements parameters 3 6 5 6 5 7 raw data from measurement 3 13 significance 1 3 units expressing 3 2 Thermal tab continuous measurement mode parameters set in 5 6 5 7 defining thermal measurement settings 3 6 Thermal Transport connection cable connector ports 2 6 function 2 6 C 1 part number 1 2 sample connections C 2 in Thermal Transport connection diagram A 2 Thermal Transport control center measurement menu 3 5 3 8 opening 3 3 showing system status 3 9 tabs 3 3 3 5 Thermal Transport log identifying calibration files 3 2 recording errors 3 14 recording messages 3 9 viewing 3 2 Thermal transport measurements See Measurements Thermal Transport option activating 5 3 A 3 connection diagram A 2 data files See Measurement data files Raw data files design benefits 1 7 hardware 2 1 See also Thermal Transport connection cable Thermal Transport sample puck User bridge board User s kit WaveROM EPROM installing A 1 A 3 See a
27. 3 8 PPMS Thermal Transport Option User s Manual Quantum Design Chapter 3 Software 3 3 3 Quantum Design Section 3 3 Thermal Transport Control Center Table 3 1 PPMS system data items that can be saved to the TTO measurement data file Items in bold and all capital letters are always written to the data file ITEM DEFINTION GENERAL STATUS General system status coded Appendix B explains how to interpret status code TEMPERATURE System temperature measured at base of sample chamber MAGNETIC FIELD Magnetic field Sample Position For use with rotator probes SAMPLE PRESSURE Pressure in sample chamber measured in torr Digital Inputs Eight bit status of selected inputs Dr Ch 1 2 Current Current delivered by selected driver output channel Dr Ch 1 2 Power Power delivered by selected driver output channel Brg Ch 1 4 Resistance Resistance of selected user bridge channel Brg Ch 1 4 Excitation Excitation current of selected user bridge channel Sig Ch 1 2 Input Voltage Input voltage for selected signal channel Map 20 29 User designated data items Reserved for hot and cold MAP 21 22 sample thermometers Rotator probes are not currently available for use with TTO System Status Features in the Thermal Transport control center provide constant updates of TTO status The Status bar at the bottom of the Thermal Transport control center succinctly describes the progress of an on g
28. 4 Driven mode stable at final field 5 Driven mode final approach 6 Charging magnet at specified voltage 4 7 7 Discharging magnet 8 Magnet reset 9 Current error incorrect current in magnet 10 Persistent switch heater error 11 Magnet quench 12 Magnet charging error 14 Power supply error 15 General failure in magnet control system BITS VALUE CHAMBER STATUS 0 Status unknown 1 Purged and sealed 2 Vented and sealed 3 Sealed condition unknown 4 Performing purge seal routine Sean 5 Performing vent seal sequence 6 Pre pump turbo pump High vacuum evacuate cryopump 7 High vacuum 8 Pumping continuously 9 Pre vent Flooding continuously 14 High vacuum error 15 General failure in gas control system continues B 2 PPMS Thermal Transport Option User s Manual Quantum Design Appendix B Status Codes and Error Messages Section B 2 System Status Codes Table B 1 Status Associated with Bits of General System Status Field Description of General System Status Measure Codes Continued BITS VALUE SAMPLE POSITION STATUS 0 Status unknown 1 Sample stopped at target value iene 5 Sample moving toward set point 8 Sample hit limit switch 9 Sample hit index switch 15 General failure B 2 2 Thermal Transport System Status Codes Table B 2 TTO Status Codes ERROR BIT FIELDS Computation poor curve fit 1 5 Computation no curve fit 6 10 Reserve
29. 8 CRC Handbook of Chemistry and Physics Boca Raton FL CRC Press Quantum Design PPMS Thermal Transport Option User s Manual References 1 Index AC board function 2 7 housing WaveROM 2 5 2 6 ACT option hardware 2 7 required for Thermal Transport option 1 2 A 3 AC Transport Measurement System See ACT option Advanced tab in control center 3 5 in Measurement dialog box 3 8 Baffle assembly 2 8 Calibration files 3 2 Calibration fixture plugging into puck 2 9 in user s kit 2 3 Charcoal holder 2 8 2 9 Connection diagram A 2 Contact baffle 2 8 Continuous Low Temperature Control option 1 2 Continuous measurement mode parameters 5 6 5 8 ramping temperature 5 5 system operation 1 3 5 9 See also Thermal Transport software Models using 5 4 Control center See Thermal Transport control center Cryopump See High Vacuum option Data files See Measurement data files Raw data files Data File tab 3 3 3 4 Data logging dialog accessing 3 8 Data plotting in Waveform tab 3 4 Data troubleshooting jumps 6 1 6 2 thermal radiation tail 6 3 Electrical resistivity estimating errors 1 9 1 10 how measured 1 6 5 9 measuring 5 1 5 5 See also Measurements parameters 3 7 5 8 raw data from measurement 3 13 significance 1 3 units expressing 3 2 Epoxy for sample leads 4 3 Error Count dialog box 3 14 ExportData exe program 3 14 Quantum Design PPMS Thermal Transport Option User s
30. Manual Figure of merit estimating errors 1 9 1 10 how measured 1 6 5 9 measuring 5 1 5 5 See also Measurements significance 1 3 Four probe lead configuration 4 4 4 5 Hardware ACT option 2 7 High Vacuum option 2 8 installing A 1 A 2 Thermal Transport option 2 1 See also Thermal Transport connection cable Thermal Transport sample puck User bridge board User s kit WaveROM EPROM Header data file 3 10 3 11 Heat loss correction 1 11 High Vacuum option hardware 2 8 required for Thermal Transport option 1 2 starting 5 3 troubleshooting 6 3 Immediate mode measurements See Interactive measurements Infrared emissivity estimating 5 2 Installation hardware A 1 A 2 secondary 1 11 software A 3 Install tab 3 3 Interactive measurements 3 1 3 5 5 5 See also Measurements Isothermal radiation shield function 2 2 part number 1 2 Lead configurations 4 4 4 5 Log file See Thermal Transport log Magnetic field range 1 2 Maintenance See Puck adjustment tool Puck fingers Measurement data files active identified in control center 3 10 format 3 11 3 12 header 3 10 3 11 saving marginal measurement results 3 5 saving PPMS system items 3 8 3 9 storing sample measurement data 3 2 3 10 5 5 viewing 3 14 Index 1 Index Measurements defining 5 4 See also Mode tab Resistivity tab Settings tab Thermal tab modes See Continuous measurement mode Single measurement mode plottin
31. QuantumDesign Physical Property Measurement System Thermal Transport Option User s Manual Part Number 1684 100B Quantum Design 11578 Sorrento Valley Rd San Diego CA 92121 1311 USA Technical support 858 481 4400 800 289 6996 Fax 858 481 7410 Third edition of manual completed October 2002 Trademarks All product and company names appearing in this manual are trademarks or registered trademarks of their respective holders U S Patents 4 791 788 Method for Obtaining Improved Temperature Regulation When Using Liquid Helium Cooling 4 848 093 Apparatus and Method for Regulating Temperature in a Cryogenic Test Chamber 5 311 125 Magnetic Property Characterization System Employing a Single Sensing Coil Arrangement to Measure AC Susceptibility and DC Moment of a Sample patent licensed from Lakeshore 5 647 228 Apparatus and Method for Regulating Temperature in Cryogenic Test Chamber 5 798 641 Torque Magnetometer Utilizing Integrated Piezoresistive Levers Foreign Patents U K 9713380 5 Apparatus and Method for Regulating Temperature in Cryogenic Test Chamber C ONTENTS Table of Contents PREFACE ouest datus utat ott ueste M ota scs eif cesta Sakic ha al Meu vii Contents and Conventions uesietarateotes ierat ira iat Ra ti d uhi e d Po RR a E Pn A FE EU ot vii LU cICDIEMEE vii P2 Scope of the Manual 2s 3 06 denies eb pe parete dete eig eoi tib
32. RATION Thermal Transport sample puck including 4084 570 Isothermal radiation shield 4084 575 Figure 2 1 4084 579 Two plug in thermometer shoes 4084 580T Figure 2 1 Plug in heater shoe 4084 585 Figure 2 1 User s kit 4084 569 Figure 2 3 Two nickel standard samples 4084 593 Figure 2 3 WaveROM EPROM for AC board 3084 043 Figure 2 4 Thermal Transport connection cable 3084 582 Figure 2 5 Thermal Transport software module 1 2 PPMS Thermal Transport Option User s Manual Quantum Design Chapter 1 Introduction 1 2 1 1 3 1 3 1 1 3 2 Section 1 3 Measurement Modes Purpose of Measuring Thermal Transport Properties In measuring the thermal transport properties of a material specimen such as thermal conductivity xK and Seebeck coefficient a a researcher can learn considerable information about the electronic as well as the ionic lattice structure of that specimen Thermal conductivity is a measure of the ability of a material to conduct heat so measuring this quantity provides information about scattering of heat carrying phonons and electrons The Seebeck coefficient describes the thermal diffusion of free charge carriers electrons or holes which creates an electric field inside a material when a temperature gradient is sustained Much like the electrical resistivity this property is very sensitive to subtle changes in the electronic scattering processes and can be a powerful probe in that regard Taken together
33. Shoe Assemblies A spare set of uncalibrated shoe assemblies two thermometers and one heater is included in the TTO user s kit You can easily calibrate the shoe assemblies by using the calibration wizard see Figure 2 10 that is accessed in the Advanced tab of the Thermal Transport control center To calibrate new shoe assemblies the calibration fixture 3084 576 must first be plugged into the Thermal Transport puck as shown in Figure 2 9 The vertical plate that is usually mounted between the sample and the plugs for the shoe assemblies must be removed before plugging in the calibration fixture Unscrew the two Phillips head screws at the base of the plate only enough to remove the plate and then retighten the screws to hold the PC board Use caution so that you do not strain the wiring on the bottom side of the PC board do not lift or turn the board or pinch any wires when retightening the screws If a heater shoe is being calibrated plug it into the left hand socket the socket closest to the marking PCB 3084 576 see Figure 2 9 If calibrating thermometer shoe assemblies plug them into the other two sockets with Thermometer A in the middle socket and Thermometer B in the right hand socket Note that wiring in the shoe assemblies is symmetric so plugging in the connectors in either of the two possible orientations will make the proper electrical connections Next locate a gold plated copper calibration sample from
34. System PPMS MultiVu Application User s Manual contains more information on data file headers When you create a data file the software prompts you to enter the physical dimensions and an estimate of the emissivity for the sample whose measurement data will be saved to the file To enable you to do this the data entry fields in the Thermal Transport control center s Sample tab are enabled As soon as you define the sample properties and select OK all data entry fields in the Sample tab Figure 3 4 are disabled again 3 10 PPMS Thermal Transport Option User s Manual Quantum Design Chapter 3 Software PE E RGB NOT Section 3 4 Thermal Transport Data Files Because the data file header identifies a particular sample changing samples without changing data files can destroy the validity of the data in the file Therefore you are encouraged to use the automated routines in the Thermal Transport control center These automated routines prompt you for new data file s and new sample information after you install a different sample 3 4 3 Format of Measurement Data Files Quantum Design Table 3 2 lists and describes all data columns in the Thermal Transport data file Section 5 3 provides more information on some of these fields Table 3 2 Fields in Thermal Transport Measurement Data File ITEM DEFINITION Time Stamp Time of measurement data point expressed in minutes or seconds and as an absolute time or re
35. TYLE Stability DEFINITION System takes first measurement in heater off state once temperature stability at both hot and cold sample thermometers is within a specified window stated either as a percentage of T or as an absolute number in kelvin After heat is applied system waits for the same stability criterion to be met before taking final measurement Heater power is turned off after conclusion of this mea surement User specified timeout forces system to take a measurement at timeout period even if stability criterion has not been met Timed Sends heat pulse of user specified duration into sample System takes a mea surement of temperatures and thermal voltages before applying heat and then takes final measurement at end of heat pulse PPMS Thermal Transport Option User s Manual Quantum Design Chapter 1 Introduction 1 4 1 4 1 1 4 2 Section 1 4 Measured Thermal Properties Measured Thermal Properties The TTO system is set up to measure four thermal transport properties e Thermal conductivity e Seebeck coefficient e Electrical resistivity e Thermoelectric figure of merit If thermal conductivity Seebeck coefficient and electrical resistivity are all measured then the thermoelectric figure of merit which is the algebraic combination of these three measurements can be determined Separate measurement protocols are provided for thermal conductivity Seebeck coefficient and elec
36. Transport Option User s Manual Resistivity measurement See Electrical resistivity Resistivity option 1 2 Resistivity tab continuous measurement mode parameters set in 5 8 defining resistivity excitation parameters 3 7 illustration 3 7 5 8 ROM See WaveROM EPROM Sample checking electrical contact 4 5 connecting leads to 5 2 connections C 1 C 3 dimensions measuring 5 2 See also Measurement data files Header four lead requirement 4 1 5 2 geometry 4 2 heat loss correction 1 11 idealized connections for 1 7 installing 5 3 lead length 4 1 measuring See Measurements Taking minimizing resistance 4 1 mounting 5 3 See also Lead configurations Puck mounting station puck See Thermal Transport sample puck response diagram of 1 8 Sample tab 3 4 Seebeck coefficient estimating errors 1 9 1 10 how measured 1 5 5 9 See also Thermal Transport software Models of manganin leads 1 11 measuring 5 1 5 5 See also Measurements parameters 3 6 5 6 5 7 raw data from measurement 3 13 significance 1 3 units expressing 3 2 Sequence measurements See also Measurements ramping temperature 5 5 taking 5 5 versus usage in other PPMS options 3 1 Settings tab continuous measurement mode parameters set in 5 7 defining basic measurement settings 3 5 Shoe assemblies calibrating new 2 9 2 10 description 2 2 Single measurement mode parameters 5 8 ramping temperature 5 5 styles 1 4 system operation
37. Transport Software esee eene enne nennen rennen ene nennen nene A 3 APPENDIX B Status Codes and Error Messages sss B 1 Bil Introductio uite entente dr a a Eid eire REG E ene eere iD eee B 1 B 2 System Status Codes e ete ole en be tolenibe egi eati e B 1 B 2 1 General PPMS System Status Codes sesir ienen oeer te ou eian ennemi ennt tenete B 1 B 2 2 Thermal Transport System Status Codes eese eene nennen rennen nenne B 3 APPENDIX C Pinout Tables o oo ga od is mu dtu tac dM c OEE E C 1 CT Introd ction uec etie eti ete eite eng os eahatecuvdests O thud Memsopess tees C 1 C 2 Thermal Transport Pinouts eese nnne enne ener erret EE e SENA e tent tenen rris C 1 C21 Sample Connections aie ede ee e pepe om mtr ee e pe eg C 1 Ref r6BnCOS oed eh rfr reip sabeis e unb tris References 1 ICO EE E RAE EAE EE ee ee Lu EDMIE D DUE I FILII ene ene eee ID UU ELE Index 1 Quantum Design PPMS Thermal Transport Option User s Manual ni Contents Table of Figures Figures Figure 1 1 Thermal and Electrical Connections for an Idealized Sample eene 1 7 Figure 1 2 Heat Pulse and Temperature and Voltage Response at Hot and Cold Thermometer Shoes in an Ideahzed Sample once RE Rn em te ie ipee bes Pega cx ER ERES 1 8 Figure 2 1 TTO Puck with Radiation Shield eese nennen nee enne enne 2 2 Figure 2 2 Puck Mounting Station with P
38. User s Manual Quantum Design C HAPTER 4 Sample Preparation 4 1 4 2 Introduction This chapter contains the following information e Section 4 2 discusses sample mounting e Section 4 3 explains how to check considerations the sample contact e Section 4 3 discusses the two probe and e Section 4 5 explains how to use the four probe lead configurations puck mounting station Sample Mounting Considerations Four leads must be attached to the sample in order for the TTO system to take thermal and electrical measurements These four leads are a heater and current I a heat sink and current I and two temperature and voltage probes that are along the length of the sample The TTO system takes both thermal and electrical measurements by using the same probes so measurements of thermal conductivity thermopower and electrical resistivity can be performed in one pass without remounting the sample It is important that the resistance either thermal or electrical at the interface between the leads and the sample be minimized This is especially important when a two probe measurement Section 4 3 1 is performed because any contact resistance is directly reflected in the measured sample thermal and electrical resistance In addition you are advised to minimize the thermal diffusion time in the leads by keeping them short 2 3 millimeters if possible because this expedites the measurement process Quantum Design PPMS Th
39. al conductance of the epoxies decreases very rapidly below 100 K so the thermal contact resistance may be significant at low temperature even if it is not at room temperature If you know the cross sectional area and the approximate thickness of the epoxy used then you can estimate the contact resistance due to the thermal resistance of the epoxy using the data in Table 4 2 and the equation for the thermal resistance 1 K l x I A where A is the cross sectional area of the bond and is the thickness of the epoxy in the bond PPMS Thermal Transport Option User s Manual Quantum Design Section 4 3 Chapter 4 Two Probe and Four Probe Lead Configurations Sample Preparation Table 4 2 Approximate thermal conductance of epoxies TEMPERATURE SILVER FILLED H20E EPOXY TRA BOND 816 H01 EPOXY K x W m K K W m K 300 2 1 100 1 0 5 30 0 5 0 2 10 0 2 0 09 5 0 1 0 03 2 0 03 0 01 4 3 2 Four Probe Lead Configuration Use a four probe lead configuration method when sample resistivity thermal or electrical is too low to allow you to neglect the contribution of lead contact resistance Thus the four probes are attached individually and you avoid the problem of contact resistance at the Thot V and T o14 V probes This is because very little thermal or electrical current passes into the copper shoes from the sample and hence they approximate much better the ideal of passive probes of the sample s te
40. ample heater and takes resistivity measurements Table 1 1 on the following page lists the TTO system requirements Quantum Design PPMS Thermal Transport Option User s Manual 1 1 Section 1 2 Chapter 1 Overview of the Thermal Transport Option Introduction Table 1 1 System Requirements for the Thermal Transport System COMPONENT FUNCTION PPMS Resistivity Option Provides user bridge board that reads two Model P400 thermometer shoes PPMS AC Transport Measurement System Outputs current to heater and sample while Model P600 providing low noise phase sensitive detection PPMS High Vacuum Option Provides thermal isolation for measurements Model P640 PPMS MultiVu Software Version 1 1 6 or Later Cryopump or Turbo Pump may be used Provides single user interface for PPMS and PPMS options Tn addition to the requirements in Table 1 1 the PPMS Continuous Low Temperature Control CLTC option Model P800 is highly recommended CLTC provides extended low temperature control Table 1 2 Thermal Transport System Parameters PARAMETER VALUE Pressure High vacuum 10 torr If you require use of significant magnetic fields H gt 0 1 T at temperatures below T Temperature 1 9 390 K 20 K please inquire with Quantum Design Magnetic field 0 14 T when gt 20K Table 1 3 Thermal Transport System Components COMPONENT PART NUMBER ILLUST
41. ar the puck This is important when high vacuum is enabled high vacuum reduces the amount of thermal exchange gas in the sample chamber You insert the contact baffle into the brass fitting that is at the bottom of the baffle assembly see Figure 2 8B To help safeguard the contact baffle use it only when you are using the High Vacuum option Handle the contact baffle with care and avoid touching the delicate outer contact fingers The charcoal holder is used to achieve the best vacuum at low temperatures and should always be screwed onto the bottom of the contact baffle when in the high vacuum state However when performing a temperature calibration of any sample hardware such as TTO shoe assemblies the charcoal holder should be removed to ensure that adequate thermal exchange gas remains in the sample chamber at low temperature BAFFLE ASSEMBLY BAFFLE a FFLE ASSEM F J BLANKING FLANGE E E d E i CHARCOAL HOLDER Figure 2 7 Baffle Assembly with Contact Baffle CONTACT FINGERS CHARCOAL HOLDER A Charcoal Holder Removed for Puck Calibration B Charcoal Holder Installed for Normal Operation Figure 2 8 Close up View of Contact Fingers and Charcoal Holder on Contact Baffle Assembly 2 8 PPMS Thermal Transport Option User s Manual Quantum Design Chapter 2 Hardware 2 5 E NOTE Section 2 5 Calibrating New Shoe Assemblies Calibrating New
42. as the sample resistivity If the thermoelectric figure of merit is sought then ZT o x T k x p is computed and written to the data file Single measurements which are generally most useful to advanced users with specialized requirements are subdivided into stability and timed measurement methods In the stability technique you specify requirements for thermal stability at the hot and cold thermometer probes on the sample and a user defined heater power is applied only after the stability criterion is met Temperature and or voltage data points are taken in the quiescent state before the heater is turned on and heater power is applied until thermal stability is once again achieved at both thermometer probes at which point the second series of data points is taken In a timed measurement you set a fixed period and power for one heater pulse Note that in all these single mode thermal measurements data points are taken only at the end of the settling time and at the end of the heater on segment and it is assumed that AT AT AT and AV AV on AV or represent asymptotic steady state values that is no curve fitting of the data is performed See Section 1 5 for more information on the theory of operation for the Thermal Transport option Quantum Design PPMS Thermal Transport Option User s Manual 5 9 C H A P T ER 6 Troubleshooting 6 1 Introduction This chapter contains the following information Section 6 2 offers su
43. asic system operations such as installing samples creating data files and setting up and running immediate mode measurements more natural and convenient The Thermal Transport control center opens as soon as the Thermal Transport option is activated in PPMS MultiVu and although it may be minimized does not close until the option is deactivated Figures 3 2 through 3 6 illustrate the tabs in the Thermal Transport control center 3 3 1 Control Center Tabs Thermal Transport SIM No Datafile E 3 Data File Sample Waveform Advanced Chamber Status Purged and sealed Press Hi ac to prepare for Measuring or VENT to insert or remove the sample Install Wizard Vent Hi ac Status Measure Help Thermal Transport Ready Figure 3 2 Control Center Install Tab Thermal Transport SIM nickel dat Em zl x Install Data Fie Sample Waveform Advanced Path c A dPpms D ata File Name nickel dat Title Iv Capture Raw Data Browse View Status Measure Help Thermal Transport Ready Figure 3 3 Control Center Data File Tab Quantum Design PPMS Thermal Transport Option User s Manual The Install tab automatically opens when the software starts and it assists you in sample installation or removal by providing sample chamber Vent and HiVac buttons and by also providing an install wizard with more extensive step by step instructions for setting up a
44. asurement System AC Transport Option User s Manual PPMS Thermal Transport Option User s Manual A 3 A PP E NDIX B Status Codes and Error Messages B 1 Introduction This appendix contains the following information e Section B 2 lists the system status codes for the PPMS and for TTO B 2 System Status Codes B 2 1 General PPMS System Status Codes Table B 1 Status Associated with Bits of General System Status Field Description of General System Status Measure Codes BITS VALUE TEMPERATURE STATUS 0 Status unknown 1 Normal stability at target temperature 2 Stable 5 Within tolerance waiting for equilibrium 6 Temperature not in tolerance not valid s 7 Filling emptying reservoir 10 Standby mode invoked 13 Temperature control disabled 14 Request cannot complete impedance not functioning 15 General failure in temperature system contact Quantum Design continues Quantum Design PPMS Thermal Transport Option User s Manual B 1 Section B 2 Appendix B System Status Codes Status Codes and Error Messages Table B 1 Status Associated with Bits of General System Status Field Description of General System Status Measure Codes Continued BITS VALUE MAGNET STATUS 0 Status unknown 1 Persistent mode stable 2 Persist switch warming 3 Persist switch cooling
45. asurement does not run until you select the Start button in the Thermal Transport Measurement dialog Data from any measurement is automatically saved if a data file is open 5 2 8 2 RUNNING THE MEASUREMENT IN A SEQUENCE To run a measurement in sequence mode you run a sequence that contains TTO Measure commands under Measurement Commands The measurement is taken automatically when PPMS MultiVu reads the measurement command in the running sequence Thermal measurements in sequence mode can generally be taken in two ways Slowly ramp the temperature rate 0 5 K min and measure continuously This method uses the Set Temperature sequence command and is usually the more expedient technique Scan in temperature or magnetic field and take single measurements after the system has stabilized at the new temperature or field This method uses the Scan Temperature Scan Field commands Data from any measurement is automatically saved if a data file is open The Physical Property Measurement System PPMS MultiVu Application User s Manual discusses sequence files and all standard system sequence commands in detail Scanning or Ramping the Temperature While Measuring In either interactive or sequence mode the most common measurement technique is to start continuous measuring and then ramp the temperature slowly by using the Set Temperature command with a slow rate slew rates are typically 0 1 1 K min For example if the system is a
46. ater block located at the bottom of the sample chamber Solid thermal contact between the chuck fingers and the heater block is especially important for high vacuum applications such as heat capacity and thermal transport measurements The puck adjustment tool consists of two metal cylinders In Figure 7 1 cylinder 1 is the finger spreader and cylinder 2 is the finger contractor and the test cutout The finger spreader and the finger contractor adjust the tension of the chuck fingers The test cutout which has the same dimensions as the cutout in the heater block tests how well the chuck fingers will contact the heater block You use the puck adjustment tool on the puck after you have inserted the puck into the sample chamber approximately 10 times or whenever the puck fits loosely into the bottom of the sample chamber NTRACTOR N N NEIG Y A MEA NDER CYLINDER 2 Figure 7 1 Puck Adjustment Tool Quantum Design PPMS Thermal Transport Option User s Manual 7 1 Section 7 3 Chapter 7 Greasing the Puck Fingers and the Coldfoot Clamp Maintenance T2 Complete the following steps to use the puck adjustment tool Screw the thermal radiation shield onto the TTO puck Place the puck on the finger spreader Refer to Figure 7 1 Turn the puck until the screw heads on the bottom of the puck line up with the grooves inside the finger spreader Press the puck downward and continue pressing until all chuck fingers touch the ba
47. blies is corrected for in the data from the Conductance W K and Conductivity W m K columns in the data file However no corrections are made in the Raw Conductance W K data Section 1 5 5 explains how to correct for heat losses in TTO measurements PPMS Thermal Transport Option User s Manual Quantum Design Chapter 5 Measurements 5 2 3 5 2 4 5 2 5 Section 5 2 Taking Thermal Transport Measurements Mount the Sample in Place the puck in the Thermal Transport puck mounting station and clamp the I coldfoot sample lead to the coldfoot on the puck by using the small Phillips screwdriver included in the user s kit Affix the shoes to the three remaining leads consistent with Figure 4 1 or 4 2 by using the small slotted screwdriver and tweezers to hold the probe shoes Use enough force to make the M1 screws snug but do not overtighten them because overtightening damages the soft copper of the probe shoe Note that the white connector plug on the Tho V shoe assembly plugs into the puck at the middle socket which is painted red while T 4 V plugs into the blue socket As a convenience in sample mounting you may use the red and blue Sharpie permanent markers included with TTO to color the white surfaces on both ends of the hot and cold thermometer shoe assemblies Note When attaching the heater shoe make sure the lead does not touch the heater resister s solder pad potentially causing an electrical short 3 Note
48. connected to the ultra low noise preamplifier of the ACT system Quantum Design PPMS Thermal Transport Option User s Manual 1 5 Section 1 4 Chapter 1 Measured Thermal Properties Introduction 1 4 3 Electrical Resistivity The TTO system measures electrical resistivity p by using a precision DSP current source and phase sensitive voltage detection The specifications for this AC resistivity measurement are essentially identical to those for the AC Transport Measurement System ACT option because the same high performance hardware is used by both TTO and ACT The Physical Property Measurement System AC Transport Option User s Manual discusses the ACT measurements in detail 1 4 4 Figure of Merit The dimensionless thermoelectric figure of merit ZT is determined here simply as the algebraic combination ZT a T p of the three measured quantities thermal conductivity Seebeck coefficient and electrical resistivity discussed above 1 6 PPMS Thermal Transport Option User s Manual Quantum Design Chapter 1 Introduction 1 5 1 5 1 1 5 2 Section 1 5 Theory of Operation Theory of Operation Benefits of the design of the TTO system include the following e Four terminal geometry minimizes the effects of thermal and electrical resistance of the leads Continuous measurements while slewing in temperature provide high density of data e Careful attention to the removal of effects of temperature drift thermal radiat
49. d 11 16 Fatal Error software 17 21 Fatal Error hardware 22 26 Reserved 27 32 In Table B 2 poor curve fit means that the residual of the fit was greater than 50 or that the Period Ratio was less than 4 and no curve fit means that the software was unable to fit the data to the model The five bits for each error category represent respectively errors in thermal conductivity Seebeck coefficient first resistivity second resistivity or figure of merit At a glance you can interpret the TTO status code as the following code 0 1 lt code lt 32 33 code 1024 code 1024 Quantum Design No errors in measurements or computations One or more poor computed curve fits One or more failed curve fits Fatal error PPMS Thermal Transport Option User s Manual A P PEN DIX C Pinout Tables C 1 C 2 C 2 1 Introduction This appendix contains the following information e Section C 2 discusses and illustrations the pinouts for the TTO system Thermal Transport Pinouts The following table and diagram detail the pinouts for each connector in the TTO system The diagram illustrates hardware ports not connectors at the end of the cables Sample Connections The Thermal Transport connection cable Figure 2 5 has connections to both the Model 7100 AC Transport controller and the Model 6000 user bridge board As in the case for the AC Transport ACT option connections from the Model 7100
50. d by making sure that they do not tend to separate When the shoes are placed in this special configuration it is recommended that you take measurements in single mode because the fitter algorithm used in continuous mode often does not adequately model this thermal circuit The reason this technique works is that the stray conductance due to the shoe assemblies Kghoes was estimated in a configuration in which the heater and hot thermometer were isothermal However in real samples the heater will always be hotter than the hot thermometer so that some thermal radiation from the heater is not entirely accounted for 6 4 High Vacuum Problems For help troubleshooting the PPMS High Vacuum option please refer to the appropriate manual either the Physical Property Measurement System Turbo Pump High Vacuum Option User s Manual or the Physical Property Measurement System Cryopump High Vacuum Option User s Manual depending on the type of high vacuum system that you have Quantum Design PPMS Thermal Transport Option User s Manual 6 3 C H A P T ER 7 Maintenance 7 1 7 2 Introduction This chapter contains the following information e Section 7 2 explains how to use the puck e Section 7 3 explains how to grease the adjustment tool puck fingers and the coldfoot clamp Using the Puck Adjustment Tool The puck adjustment tool Figure 7 1 adjusts the tension in the chuck fingers so that the fingers maintain solid thermal contact with the he
51. d onto the puck The copper metal is soft so excessive force or misthreading of the piece can easily damage the threads PPMS Thermal Transport Option User s Manual Quantum Design Chapter 2 Hardware 2 2 2 Section 2 2 Thermal Transport Hardware User s Kit The user s kit contains miscellaneous hardware and consumables that are needed for mounting leads on samples as well as calibrating the spare shoe assemblies provided with the Thermal Transport option The convenient portable toolbox see Figure 2 3 on the following page helps keep the items in the kit organized The contents of the user s kit include the following Quantum Design Puck mounting station A pivoting rotating socket is mounted to a heavy base Figure 2 2 and holds the Thermal Transport sample puck in a fixed position giving you better access to the sample leads while you are connecting the shoes or making other adjustments Tighten the two thumbscrews on the mounting station once the desired orientation for the puck is achieved O PUCK ASSY WITHOUT SHIELD 4084 570 PUCK MOUNTING STATION ASSY 4084 600 Figure 2 2 Puck Mounting Station with Puck Nickel calibration samples Two comb shaped samples made of nickel are used as standards for all measured thermal transport properties Refer to Section 2 2 3 for more information on the nickel samples Gold plated copper samples Two similar comb shaped samples of copper are provided as ther
52. data points are usually of poor quality because parameters were still in the process of being optimized PPMS Thermal Transport Option User s Manual 5 7 Section 5 3 Chapter 5 Measurement Mode Parameters Measurements 2 gt c NOTE 3 3 2 5 8 Thermal Transport Measurement B ic xj 4 p Last Measurement 34 Settings Thermal f Limits and Settings Temp 308 18 K Min Max Field 70000 Oe Excitation 0 1 1 Conduct 118 44 W K m Frequency 10 300 Seebeck WK Duration E sec Resist Ohm m v Constant Current Mode zT Low Resistance Mode Period sec C Always Autorange Power mw 9 EE RUE r Lurrent Measurement C Fixed Range i ink Period 80 98 sec Power 29 8 mw Progress Stop Pause Close Help rs Figure 5 2 Resistivity Tab in Thermal Transport Measurement Dialog Box Table 5 3 Resistivity Excitation Parameters for Continuous Mode Measurements PARAMETER FUNCTION Excitation Defines minimum and maximum excitation amplitude in milliamps Frequency Defines minimum and maximum measurement frequency in Hz Duration Defines measurement duration in seconds The parameters for resistivity measurements are adjusted adaptively in the continuous measurement mode in the same way as the heater power and period are allowed to vary Refer to the Physical Property Measurement System AC Transport Optio
53. ductive epoxies is their very high strength Use a generous but not excessive amount of epoxy when attaching leads so that the bond is strong and provides very good thermal contact The sample mounting kit contains starter samples of epoxies including Silver Filled H20E from Epoxy Technology Inc and nonconductive Tra Bond 816H01 from Tra Con Inc Product specifications and Materials Safety Data Sheets MSDS s for both epoxies are included in the epoxy kit 4 2 2 1 SILVER FILLED H20E EPOXY Small amounts of parts A and B labeled on the containers should be thoroughly mixed in an approximately 1 1 ratio on a clean dry and nonabsorbing surface using care that no cross contamination of the remaining portions in the jars occurs After applying the mixture to the leads and sample and attaching the leads you can bake the sample at 150 C for about 5 minutes See the vendor s product data sheet included in the epoxy kit for more information including other possible curing schedules 4 2 2 2 TRA BOND 816H01 EPOXY This electrically nonconductive epoxy is provided in one use 2 gram packets Because 2 g is a much larger amount of epoxy than is needed for one sample Quantum Design recommends preparing several samples at the same time To mix slide off the plastic clamp and knead both chambers thoroughly so that the texture feels uniform this occurs after approximately 2 minutes of mixing Cut open one end of the packet to dispense
54. e PC b select the A drive c select setup exe and then d complete all operations the InstallShield wizard prompts you to perform The TTO software runs in conjunction with the PPMS MultiVu software PPMS MultiVu must be installed on the host computer in order for the TTO software to work If you try to install the TTO software before you install PPMS MultiVu the InstallShield wizard for the TTO software fails and generates a warning message which tells you to install PPMS MultiVu Install the TTO software Do the following a insert Disk 1 for the TTO software into the PC b select the A drive c select setup exe and then d complete all operations the InstallShield wizard prompts you to perform Activate the Thermal Transport option in PPMS MultiVu Do the following a start up PPMS MultiVu b select Utilities gt Activate Option c click on Thermal Transport under the Available Options heading and then d select the Activate button As soon as you activate the Thermal Transport option the Thermal Transport control center opens and the Measure menu items and measurement sequence commands that are specific to TTO appear in the PPMS MultiVu interface Note that in order to run TTO requires that the AC Transport ACT option be installed because TTO and ACT share the hardware configuration file C QdPpms ACTrans Calibration Actcal cfg For information about installing the ACT option refer to the Physical Property Me
55. e as the measurement data file but a raw file extension instead of a dat file extension 5 2 7 Define the Measurement 1 Decide which mode continuous or single to use for the measurement Continuous mode is the software default and generally offers the most rapid data acquisition Single mode offers the most direct control of the measurement To specify single mode measurements use the Mode tab of the Thermal Transport Measurement dialog Figure 3 10 Single mode measurements may be steady state or timed Refer to Section 5 4 for more details about each measurement 2 Decide whether to take the measurements directly by accessing the Thermal Transport Measurement dialog select the Measure button in the control center or to run the measurements in a PPMS MultiVu sequence 3 Select the Measure button in the control center so that you see the Settings tab in the Thermal Transport Measurement dialog Figure 3 7 You use the Settings tab to decide which physical quantities you want to measure thermal conductivity Seebeck coefficient electrical resistivity and if all the above are selected whether you would like the program to compute the figure of merit ZT from these measurements and put this quantity in the data file 4 Define appropriate parameters for each measurement The default values for these parameters are appropriate for most cases so it is unlikely you will need to change them e In continuous mode which uses an
56. each measurement However it may be preferable in some cases to have more direct control of the measurement for example when one measurement takes several minutes or when the adaptive software routines may not adequately adjust to rapidly changing thermal transport properties of the sample and in these cases you want to use single mode In continuous measurement mode the parameters of heater power and period as well as the resistivity excitation and frequency are continually being updated after each heater pulse to keep the Temp Rise and Period Ratio parameters near the user set values The raw data AT time is sent to the fitting algorithm which performs a three parameter nonlinear least squares fit in AT the asymptotic temperature drop across the sample as well as t and t which are a long and short time constant respectively that characterize the sample lead shoe thermal circuit Of these AT is used to calculate the thermal conductance of the sample K heater power AT while the period for the next measurement is computed from t by Period PeriodRatio x t The asymptotic Seebeck voltage AV is computed from the raw data AV time similarly except that a computationally simpler linear regression is used because t and t are based on the conductivity fitter routine The Seebeck coefficient is then simply AV AT Resistivity measurements are made before and after the heater pulse and the average of the two is taken
57. er aret vii P 3 Contents of the Manual deter teer tret tried ce reete eri retinet eei evo epa eee ea eds vii P 4 Conventions m the Manual cate deett terere ede teet de gea eee eee Laeta era aeo debe reel ned viii CHAPTER 1 IntrOdUCOOR ooo etta idiom ede Sp au dc thee e tdt 1 1 TT Tint Ctr Oni iet e a ete te eere erui ie eue da estem cente quim E RIA eta qepte 1 1 1 2 Overview of the Thermal Transport Option esses nennen nennen enne inneren enne teen inneren 1 1 1 2 1 Purpose of Measuring Thermal Transport Properties eese nee 1 3 1 3 M as rem ent Mode Sii sende dee eere noted tede Ee etes eira E dece tee ye eerte epe foie dert 1 3 1 3 1 Continuous Measurement Mode esses enne eene entente tenen nene tenen nn se tenen nnne tenen 1 3 1 3 2 Single Measurement Mode 4 tene eee tei o eR erp pl edo et cet Pe deterret efie det 1 3 1 4 Measured T herrnial Properties deii th eerte tet ehe top edes peri deted fe ep ederet dee tees 1 5 T4 T Thermal Conductivity heit e o ibd f e erit etes 1 5 1 4 2 Seebeck Coefficient ird eene tte eet pene e nde i ere Pace ecg aee minae edge dedu duet 1 5 143 Electrica Resistivity 5e ode fro Re i e dedos edere tu nite pereat E eei etes 1 6 1 4 4 Fig re of Mert nones neni igemeeatiete timeo Pedra tes 1 6 1 5 Theory Of Operation seene bred tere t bidder e dedero Rete es 1 7 INSEL m
58. ermal Transport Option User s Manual 4 1 Section 4 2 Chapter 4 Sample Mounting Considerations Sample Preparation 4 2 1 Geometry The geometry of the sample is constrained due to a variety of considerations the most obvious of which is the Thermal Transport sample puck Mounted vertically on the puck a sample cannot be much longer than 20 mm while the minimum convenient sample length is typically 3 mm Another aspect to consider is the thermal diffusion time in the sample defined as t C K where C Joule K is the heat capacity and K Watt m is the thermal conductance of the sample This places an operational lower limit on K so that the measurement time does not become excessively long one measurement is typically designed to be 8 x t see Section 1 5 Since K x A I where W m K is the thermal conductivity A is the cross sectional area of the sample and is the length this implies a lower limit on A for a given value of x Another relation that can be easily derived from the above equations is t c x Pic where c m K is the specific heat of the material This implies that for a given material the time constant simply scales quadratically with the length with a typical practical upper bound of Lmax 10 mm on samples While the thermal diffusion time t places a lower limit on A I the heater power P W x AT x A D where AT 0 03 x T typical value is the temperature drop across the sample sets t
59. es Cryogenics vol 32 no 10 1992 908 12 Quantum Design PPMS Thermal Transport Option User s Manual 1 9 Section 1 5 Chapter 1 Theory of Operation Introduction The first term is the residual of the curve fit mentioned above the second term propagates the error in the heater current heater resistance is R due to the digital analog converter the third term is the error in the estimation of the sample radiation term where 20 combined error in the estimation of sample surface area and emissivity is assumed and the last term is the error in the thermal conductance leak from the shoe assemblies K 4 where a 10 error in this correction is assumed see the next section for details on heat losses The error in the measurement of the thermal voltage AV vs time has a similar expression as equation 1 3 so the standard deviation in the Seebeck coefficient a AV AT is the following 2 2 R R o a ax E m Equation 1 5 Resistivity measurements are made both preceding and following each thermal measurement so that the average of the two p and o p values is reported in the data file The residual of the curve fits R is obtained from the stream of voltage V vs time data as the following 2 v Vi model y Residual R 1 Equation 1 6 N and the standard deviation is calculated simply as Equation 1 7 where Vpp is the peak to peak amplitude of the voltage vs time signal The
60. etiaene 5 6 5 3 1 Continuous Measurement Mode 4e oer He eie e ceri e ome ren idest ie decedunt 5 6 5 3 2 Single Measurement Mode 5 5 at Sd tte i ERE OPER PEE a Eaa 5 8 5 4 Description of Measurement Process scsssecssesssesscseeeeceseecessecseesecseesecsaeeeesaecaeesecaeeseenaeeeesaseaeesesaeeaeenaeeeeegs 5 9 CHAPTER 6 Troubleshigollle aes reor rne HER eR En tic anita a ei ds dtu babe dut 6 1 6 1 Introduction oe espe eatis A E hieu 6 1 6 2 Jumps or Noise in the Data beet eee ates wee Let eee ie n eet ear Aided 6 1 6 2 1 Gaps in the Data Versus Temperature eseseeeeseeeeee eene eene nenne nein tren enne trennen innen enne 6 2 6 22 Steps imi the Dataran cpn n ea tene oki MA E iA ial ba Pa ed 6 2 6 3 Thermal Radiation Tail in the Thermal Conductivity Data essent 6 3 6 4 High Vacuum Probl ms e booa euet ive I entered ied 6 3 CHAPTER 7 PVT IEC TANCE oc ohob dM Soda Ld AM M Ld MM CLE 7 1 WA Tint Guta om 2 acte e n te E e e RIO OHIO Ce rb ee de tems 7 1 7 2 Using the Puck Adjustment To0 l 1 1i recreo eI E Erro oni Dee e SENSES PEREN eve s is Spn 7 1 7 3 Greasing the Puck Fingers and the Coldfoot Clamp esee nee 7 2 APPENDIX A InsfallaB On iio ee PRA AAA PREG ROA n dp ON REE A 1 Ad Introduction 3 enr te p potete mate omnt e a Dec n E A 1 A 2 Installing Thermal Transport Hardware sess enne nnne nennen A 1 A 3 Installing Thermal
61. f the measurement and after the AT vs time data is fit to obtain t and c a linear least squares routine fits the data to the following equation AV model AV X 1 1 x exp t 1 T2 x exp t T2 T1 T2 bt c Equation 1 2 where AV is the asymptotic Seebeck voltage drop akin to AT in equation 1 1 b and c are parameters that describe linear drift and offset voltages respectively and v 0 t is swept so that for each value of a linear regression in AV b and c is performed Note that is used between the exponential terms and signifies that a full search is done for each sign The physical significance of this is that the Seebeck coefficient of the material responsible for the short time constant c that is the leads may be of the opposite sign as that for the material associated with the long time constant that is the sample This is in contrast to the case of the thermal conductivity which is always positive The parameter for the linear voltage drift b is included here to account for varying thermal voltages in the wiring to the sample and also the slow microvolt level drift in the preamp electronics A similar measurement technique previously published by Maldonado describes modeling of the thermal and thermoelectric response of a sample to a low frequency square wave heat pulse However the thermal circuit considered in that work was considerably simpler than that which 1s approp
62. g data in Waveform tab 3 4 process description of 5 9 properties measured 1 5 1 6 See also Electrical resistivity Figure of merit Seebeck coefficient Thermal conductivity standard for See Nickel calibration samples status shown in control center 3 9 storing data from See Measurement data files Raw data files taking 5 1 5 5 units expressing 3 2 Model 7100 AC Transport Controller function 2 7 in Thermal Transport connection diagram A 2 sample connections C 2 Mode measurement See Continuous measurement mode Single measurement mode Mode tab 3 8 See also Continuous measurement mode Single measurement mode Nickel calibration samples parameters 2 5 part number 1 2 in user s kit 2 3 Parameters continuous measurement mode 5 6 5 8 curve fitting results 3 4 nickel calibration samples 2 5 single measurement mode 5 8 system 1 2 Part numbers 1 2 Period ratio recommended value for 3 6 Pinouts C 1 C 3 PLCC chip extraction tool 2 5 2 6 PPMS MultiVu installing A 3 required for Thermal Transport option 1 2 3 1 viewing data files in 3 14 Puck See Thermal Transport sample puck Puck adjustment tool function 7 1 illustration 7 1 using 7 2 Puck fingers greasing 7 2 Puck mounting station illustration 2 3 using 4 5 Puck wiring test station 4 5 Radiation shield See Isothermal radiation shield Raw data files format 3 13 saving data to 3 10 5 4 viewing 3 14 Index 2 PPMS Thermal
63. g the heat pulse the Seebeck voltage AV V V is monitored Heat exits the sample to the coldfoot Time traces of AT and AV during the heat pulse are illustrated in Figure 1 2 COPPER LEAD Uy EPOXY BOND Electrical resistivity measurements are made both before and after the heat pulse described above COLDFOOT Current L flows through the sample and the voltage drop across the sample is monitored using Figure 1 1 Thermal and Electrical the V leads Connections for an Idealized Sample Quantum Design PPMS Thermal Transport Option User s Manual 1 7 Section 1 5 Chapter 1 Theory of Operation Introduction KA MPERATURE OWER ON Figure 1 2 Heat Pulse and Temperature and Voltage Response at Hot and Cold Thermometer Shoes in an Idealized Sample Top panel Time trace of hot and cold thermometers during an idealized heat pulse note that the PPMS base temperature is slewing Middle panel Corresponding temperature AT and voltage AV differentials across the sample indicating thermal time constants 4 and 12 and the estimate of the asymptotic differential AT Bottom panel Heater power during square wave heat pulse 1 5 3 Software Models In continuous measurement mode Section 1 3 1 the software uses adaptive algorithms to optimize measurement parameters such as heater current heat pulse period and resistivity excitation amplitude and frequency Once the AT vs time data over the
64. ggestions to help e Section 6 4 refers to high vacuum troubleshoot jumps or noise in TTO data problems Section 6 3 discusses ways to minimize errors due to radiation effects 6 2 Jumps or Noise in the Data The following are some general guidelines for ensuring good data quality 1 Quantum Design Make sure that the condition Period Ratio Period t gt 8 is met at all temperatures Considering that the maximum period is 1430 seconds your sample must be designed so that the thermal diffusion time 1 is not too long If Period Ratio is too small the curve fitting software is not able to adequately fit the data Make sure that an adequate heat pulse can be applied default is Temp Rise 3 across the sample that is the thermal conductance of the sample is not above about 20 mW K If Temp Rise falls below the 1 level data can become noisy Verify that the leads are attached to the sample with a generous amount of epoxy that is well cured and that the lengths of the leads are kept to a minimum If temperature or field is being slewed while measurements are made verify that the slew rate is slow typically less than 1 K min and uniform over the course of a measurement PPMS Thermal Transport Option User s Manual 6 1 Section 6 2 Chapter 6 Jumps or Noise in the Data Troubleshooting 6 2 1 6 2 2 Gaps in the Data Versus Temperature Check that the background temperature slewing of the system as reflected in
65. he upper limit on A l because the heater is limited by the 10 V compliance limit of the Model 7100 current source For an R 22 KQ chip heater Prax V R 50 mW Keep in mind that the constraints mentioned here are most stringent at high T where x is generally longer and the required AT is larger Table 4 1 gives some examples of sample geometries and the range of measurable thermal conductivities based on the above considerations and using a 2 kQ heater Table 4 1 Sample Geometries and Range of Measurable Thermal Conductivities DIMENSIONS HIGH T CONSTRAINTS SAMPLE zx A mm ON k W m K Brick 8x 2x2 2 30 Needle 10 x 1 x 1 10 150 Pill 3x 5x5 0 1 1 5 PPMS Thermal Transport Option User s Manual Quantum Design Chapter 4 Section 4 2 Sample Preparation Sample Mounting Considerations 4 2 2 Lead Mounting Epoxies After deciding on an appropriate geometry for the particular thermal transport measurement you will take see Section 4 2 1 you cut and sand the sample so that its surfaces are clean The epoxies used to attach leads to samples should be chosen for the following Strength in bonding to the particular sample material e High thermal conductivity e Convenience of the curing schedule In addition any time the thermoelectric or electrical properties will be measured an electrically conducting silver filled epoxy must be used On the other hand the primary advantage of electrically noncon
66. hermal Transport Option User s Manual Quantum Design A P PEN DIX A Installation A 1 A Introduction This appendix contains the following information Section A 2 explains how to install the e Section A 3 explains how to install the TTO hardware TTO software Installing Thermal Transport Hardware To install the TTO hardware you must install all components that are necessary for the TTO system These components may include the following Quantum Design Model 7100 AC Transport Controller For more information about the Model 7100 refer to section 2 3 1 in this manual and to the Physical Property Measurement System AC Transport Option User s Manual High Vacuum option The TTO system works with either the Turbo Pump High Vacuum option or the Cryopump High Vacuum option For more information about these options refer to the Physical Property Measurement System Turbo Pump High Vacuum Option User s Manual or the Physical Property Measurement System Cryopump High Vacuum Option User s Manual User bridge board For more information about the user bridge board refer to section 2 2 6 in this manual and to the Physical Property Measurement System Resistivity Option User s Manual Thermal Transport connection cable This cable must be connected as described in section 2 2 5 and as illustrated in Figure A 1 on the following page WaveROM EPROM certain systems only If the ACMS waveROM upgrade kit was included with your TTO syste
67. hermalTransport Calibration directory The TTO log can be viewed by using the View TTO Status Log menu command Thermal Transport Log Thermal Transport Initializing 3 23 2001 8 36 10 AM Resetting Controller Board ACT Firmware Version Simulation Downloading Hot Thermometer Config File Therm020 cfg Downloading Cold Thermometer Config File Therm021 cfg Reading Heater Calibration File Heater014 cal Thermal Transport Running in Simulation mode Thermal Transport Ready Figure 3 1 Thermal Transport Log Window 3 2 1 Measurement Units Thermal conductivity x is typically stated in either units of watt meter kelvin written W m K or in mW cm K In the TTO software the units of W m K are used for thermal conductivity The Seebeck coefficient is expressed most conveniently in np V K because in many electrical conductors uV K at room temperature The electrical resistivity p is stated in units of ohm meter Q m The thermo electric figure of merit ZT o T px is dimensionless when MKS units are chosen for each quantity that is a V K T K p Q m and k W m K 3 2 PPMS Thermal Transport Option User s Manual Quantum Design Chapter 3 Software 3 3 Thermal Transport Control Center Section 3 3 Thermal Transport Control Center The TTO software module has a control center that includes all frequently selected Thermal Transport commands With its easy to use tab format and software prompts the control center makes b
68. ion and other systematic errors e Robust easy to use fully automated measurements Hardware When measuring in continuous mode the DSP hardware in the Model 7100 AC Transport Controller generates the heat pulse in the chip resistor heater on the sample which can be described as an on cycle of constant power followed by an off cycle of equal duration The waveform for this pulse was programmed specially for the TTO system in the waveROM EPROM on the AC board so older AC boards must have the old waveROM swapped for the new waveROM labeled tTHRMXPT 4201 to run TTO Section 2 2 4 discusses the waveROM EPROM in more detail Figure 1 2 on the following page illustrates the heat pulse as well as the temperature and voltage response at the hot and cold thermometer shoes in an idealized sample Thermal and Electrical Circuit The thermal and electrical connections for an HEATER SHOE idealized TTO sample are shown in Figure 1 1 For clarity the sample is shown mounted in the four probe geometry The four basic physical elements are illustrated the sample the epoxy bonds that adhere the leads to the sample the copper leads and the heater and thermometer shoe assemblies that screw down onto the leads For thermal conductivity and Seebeck coefficient measurements heat is applied to one end of the sample by running current through the heater Q The temperatures Thot and Toig are measured at the thermometer shoes Also durin
69. l Transport Data Files Software 3 4 Thermal Transport Data Files Thermal Transport measurement data is stored in measurement data files and raw measurement data files Measurement data files which have a dat extension store relevant sample measurement data and selected system data for any number of measurements taken by any of the Thermal Transport measurement types Raw measurement data files which have a raw extension store raw tempera ture versus time thermal conductivity and voltage versus time Seebeck and resistivity data as well as the software s fits to the data Raw data is saved only if the Capture Raw Data check box in the Data File tab Figure 3 3 is selected The system data items that may be recorded are user configurable Section 3 4 2 The results from measurements whether made in continuous or single mode are automatically saved if a data file is open Measurement and system data is appended to the selected data files and is never overwritten The Data File tab in the Thermal Transport control center identifies the selected mea surement data file and raw measurement data file and includes a Browse command button that enables data file selection and creation The name of the selected measurement data file is also displayed in the title bar of the Thermal Transport control center 3 4 1 Saving Raw Thermal Transport Data Raw thermal transport data is saved to a separate raw measurement data file that has the identica
70. l base name as the measurement data file but a raw file extension instead of a dat extension Saving the raw data can be useful when you are deciding which measurement parameters to use or if you are concerned about signal quality A clean single wavelength sine wave is optimal in the case of AC resistivity measurements In the cases of thermal conductivity and Seebeck measurements the fitted model curve can be plotted along with the raw data so that you can easily assess the quality of the results However saving raw data creates very large data files Raw thermal transport data is saved only if a measurement data file is selected and the software is prompted to capture raw data Enabling the Capture Raw Data check box in the Thermal Transport control center s Data File tab Figure 3 3 prompts the software to save raw data By default this check box is not selected 3 4 2 Data File Header The data file header contains file and sample property information that is defined when the data file is created Information written to the data file header cannot be subsequently changed in PPMS MultiVu The file information that can be written to the header consists of the title assigned to the graph view of the data file The sample property information consists of the sample dimensions and emissivity User comments can also be written to the header All this information appears in the INFO declara tions of the header The Physical Property Measurement
71. lative to the start time of the data file Status code PPMS system status Identical to General Status in Table 3 1 Error code TTO error code Appendix B describes how to interpret the code Magnetic Field Oe Magnetic field Sample Temp K Average sample temperature during measurement Conductivity W K m Sample thermal conductivity Cond Std Dev Error standard deviation in thermal conductivity measurement Seebeck Coef uV K Sample Seebeck coefficient in units of n V K Seebeck Std Dev Error in Seebeck coefficient measurement Resistivity Ohm m Sample resistivity Resist Std Dev Error in resistivity measurement Figure of Merit ZT Dimensionless thermoelectric figure of merit ZT Delta Temp K Extrapolated asymptotic temperature drop AT across heated sample Conductance W K Net thermal conductance of sample See Section 1 5 5 Raw Conductance W K Raw thermal conductance that is Heater Power Delta Temp Seebeck Volt uV Extrapolated asymptotic Seebeck AV across heated sample continues PPMS Thermal Transport Option User s Manual 3 11 Section 3 4 Chapter 3 Thermal Transport Data Files Software Table 3 2 Fields in Thermal Transport Measurement Data File Continued ITEM DEFINITION Min Temp K Minimum temperature at either hot or cold thermometer during measurement Max Temp K Maximum temperature at either hot or cold thermometer during measurement
72. lso Installation Secondary maintenance See Puck adjustment tool Puck fingers measurements See Measurements overview 1 1 1 2 parameters 1 2 pinouts C 1 C 3 software See Thermal Transport software status codes B 3 system requirements 1 2 Thermal transport properties significance 1 3 types measured 1 5 1 6 Quantum Design PPMS Thermal Transport Option User s Manual Index Thermal Transport sample puck affecting sample size 4 2 description 2 2 illustration with calibration fixture 2 9 with puck mounting station 2 3 with radiation shield 2 2 maintenance See Puck adjustment tool Puck fingers mounting sample on 5 3 See also Puck mounting station part number 1 2 sample connections C 2 C 3 Thermal Transport software control center See Thermal Transport control center data files See Measurement data files Raw data files design versatility 3 1 estimating errors 1 9 1 10 installing A 3 log file See Thermal Transport log models 1 8 1 9 wizards See Wizards Thermoelectric figure of merit See Figure of merit Toolbox containing user s kit 2 4 Troubleshooting data 6 1 6 3 High Vacuum option 6 3 TTO See Thermal Transport option Tto ini file 3 2 Tto Log txt file 3 9 TTO Measure command 3 1 5 5 Turbo Pump See High Vacuum option Two probe lead configuration minimizing resistance for 4 1 suggested use 4 4 User bridge board 2 7 User s kit contents 2 3 illustration 2 4 part number 1 2
73. m you must install the new ROM Refer to sections 2 2 4 and 2 2 4 1 PPMS Thermal Transport Option User s Manual A 1 Section A 2 Appendix A Installing Thermal Transport Hardware Installation 4 ER e P1 USER BRIDGE OQ 19 OG oO ce n PROBE HEAD E zl So Lu Jo Q Q J NS O f o IN T A ZEN lo 3084 512 Ol a m NC A YS 3084 515 e P5 SAMPLE e VOLTAGE IN Nijo e O I K J Lu SE PA DIGITAL P3 ANALOG P2 DRIVE ACCESS P1 SAMPLE e oO INTERFACE INTERFACE AND MONITOR CURRENT OUT 6 I e oe Oey due 5 J 3084 51 3084 582 1 mese CABLES MAY GO TO THE OPTION CONTROLLER DEPENDING ON SYSTEM CONFIGURATION Figure A 1 Thermal Transport Option Connection Diagram A 2 PPMS Thermal Transport Option User s Manual Quantum Design Appendix A Installation Section A 3 Installing Thermal Transport Software A 3 Installing Thermal Transport Software 1 Quantum Design Install the PPMS MultiVu software version 1 1 6 or later if it is not already installed Do the following a insert PPMS MultiVu Disk 1 into th
74. mal shunts to help provide an isothermal environment while calibrating shoe assemblies Calibration fixture This fixture is used in conjunction with calibration software and allows the heater and thermometer shoes to be calibrated Consumable items These items consist of a sampler of gold plated copper leads including both wires and disks a sample of two types of epoxies for mounting leads and a small tube of Apiezon H Grease to increase thermal contact between the leads and shoes or the coldfoot Chapter 4 contains more detailed information about mounting leads to samples User tools These tools include small slotted and Phillips screwdrivers for sample mounting and an extractor tool to remove the electrical connector plug ends of the shoe assemblies from the puck This extractor tool holds the connector plug by sliding into the grooves on each side of the plug PPMS Thermal Transport Option User s Manual 2 3 1 H GREASE TUBE 4084 410 02 1 MOUNTING BRIDGE ASSEMBLY 4084 608 1 PHILLIPS SCREWDRIVER 00 HM237 1 LEAD DISK ASSEMBLY 4084 609 1 SLOTTED SCREWDRIVER 1 16 HM236 1 LEAD BAR ASSEMBLY 4084 610 ra e p 5 g Te ed 4004 595 rr a Figure 2 3 Thermal Transport Option User s Kit LABEL USER KIT BOX AND FOAM
75. measurement The Data File tab lets you open a new TTO data file or append to an existing TTO data file You can also use the tab to view data and select whether raw thermal transport data is saved in a raw file See Section 3 4 for information on TTO data file formats Section 3 3 Chapter 3 Thermal Transport Control Center Software The Sample tab displays the sample name comments Install Data File 1 Waveform Advanced geometry and radiation estimates for the currently Material nickel 20 open data file These param C eters can be changed only by Lippe sheet 01 thick opening a new file in the Data foal Surface 2 File tab Chapter 4 has more Ld Ed mn Area 2 mm information on how to mount C QN Dam 0 32 mm Emissivity o5 Thermal Transport SIM nickel dat sample leads and estimate properties such as the sample s infrared emissivity Status Measure Help Thermal Transport Ready Figure 3 4 Control Center Sample Tab The time traces of the most recent raw data along with the fitted curves are displayed in the Waveform tab As a visual aid the heater pulse is shown schematically in the Waveform tab as a yellow square wave in both the thermal conductivity and Seebeck graphs Thermal Transport SIM nickel dat Amplitude 644 2 mK Time Const 3 796 sec Status Measure Help Acquiring Thermodata at 39 86K 70000 00e Figure 3 5 C
76. mperature and voltage profile Note that care must be taken to keep separate the epoxy pads on the sample or else this advantage is compromised due to thermal electrical currents that may shunt through the epoxy pads at the T V probes Figure 4 2 shows a sample mounted in the four probe configuration Figure 4 2 Example of Leads Mounted in Four Probe Configuration Quantum Design PPMS Thermal Transport Option User s Manual 4 5 Section 4 5 Chapter 4 Using the Puck Mounting Station Sample Preparation 4 4 4 5 Checking the Sample Contact If electrical resistivity or thermopower measurements will be performed on a sample electrical contact to the sample must be checked after mounting it on the puck Plug the puck into the puck wiring test station and check contact at V with an ohmmeter use the Thermal Transport overlay on the puck box For resistivity the contacts at I must also be checked Finally check that none of these leads are shorted to the puck body because this may introduce noise into the electrical measurements Using the Puck Mounting Station A puck mounting station Figure 2 2 is included in the user s kit to make mounting samples on the Thermal Transport puck more convenient The heavy steel base provides stability while the puck is mounted in the plastic socket and you can tighten the thumbscrews on the station once you have set the desired orientation of the puck The plastic socket also acts as
77. mpleted This principle is not appropriate for continuous TTO measurements because these can be performed while a system parameter such as the temperature is swept slowly Therefore the TTO Continuous Measure command initiates measurements and the sequence execution immediately continues TTO measurements are taken until the TTO Stop sequence command is issued The TTO single measurement sequence commands are more similar to the traditional measurement commands During these measurements sequence execution is paused until the measurement is completed because single measurements operate on the condition that system parameters are stable during the measurement Quantum Design PPMS Thermal Transport Option User s Manual 3 1 Section 3 2 Chapter 3 Overview of Thermal Transport Software Software The data file for TTO measurements sample dat where sample is the file name you select contains the results for each measurement that was completed successfully The raw data from all measurements can also be saved in a separate file sample raw As soon as the TTO software is activated in PPMS MultiVu the Thermal Transport Log window Figure 3 1 opens and indicates which thermometer and heater calibration files will be used These settings as well as several other parameters can be edited in the Tto ini initialization file located in the OdPpms NThermalTransport System directory The thermometer and heater calibration files are located in the QOdPpmsNT
78. n 1 3 describes the measurement modes in more detail Resistivity C Stabilityto dT 0 300 K C Timed Resist eli Period 30 01 sec Timeout 3600 sec Power 0 6364 mw Power fi mw Current Measurement Period 30 01 sec Maximum ho V Seebeck Voltage Power 0 3826 mw Progress Figure 3 10 Mode Tab in Thermal Transport Measurement Dialog Box Thermal Transport Measurement E nf xl pera ES REA dialog pu can be accessed from the Resistivity Mode 7 aj rage Advanced tab in the event that PPMS Data Logging Tene 27012 k you would like to select which Field 70000 Oe PPMS status items are written Select Data _ Conduct 64 436 WwK m to the TTO data file Table 3 1 Seebeck 50 583 uv IK on the following page r Reprocess describes the parameters that Recompute results using new Sample ZT can be monitored on the PPMS Properties Bi data logging dialog The Penod uoi Reprocess command allows EM Power _ 0 6364 mw you to recompute thermal Curent Measurement transport results from an Period 30 01 sec existing TTO data file Power 0 3826 mw dat by changing the Progress sample s estimated geometry Stat Pause Close Help udi le and emissivity and the command allows you to write these results out to a new data Figure 3 11 Advanced Tab in Thermal Transport Measurement Dialog Box file
79. n 2 2 Chapter 2 Thermal Transport Hardware Hardware 2 2 4 1 REPLACING THE WAVEROM CHIP To replace the waveROM chip on the AC board first locate the upgrade kit which contains the PLCC chip extraction tool and the new ROM in a small plastic box Remove the lid of the Model 6000 so that you can access the AC board note that the AC board may reside in the Model 6500 Option Controller instead Turn off the Model 6000 and extract the old waveROM by inserting the hooks of the extraction tool in the two slots on opposite corners of the ROM housing and gently squeezing until the chip lifts out To insert the new ROM note that the upper left corner as viewed in Figure 2 4 is notched and the upper side has the label attached Press down applying firm and even pressure to the chip until it is seated in the housing 2 2 5 Thermal Transport Connection Cable The Thermal Transport connection cable part number 3084 582 connects the sample to the Model 7100 AC Transport Controller and to the user bridge board that is in the Model 6000 PPMS Controller Two separate shielded cables on the connection cable plug into the Model 7100 These separate shielded cables split the sample signal and excitation signal in order to help prevent sample signal distortion by the excitation signal Labels on the cable s connectors Figure 2 5 identify the ports for those connectors You should also refer to Figure A 1 the Thermal Transport Option Connection Diagram
80. n 2 5 Calibrating New Shoe Assemblies Ww V V A 3 m zT Y gt a T A vt GY NN LS 27 Q bash dU NS NS dA JO N CL e N A 33 M OAS AS SN G TH AX Bli 4 2 ly p M NN A Chapter 2 Hardware THERM B THERM A HEATER Figure 2 9 Calibration Fixture Plugged into TTO Puck and Illustrating Sockets for Each Shoe Thermal Transport Calibrate Thermom m Calibrate Serial No m Heater Parameter M Therm os v Therm B 0214 v Heater 0304 Max Temp K mo Min Temp K 1 8 Excitation 1100 Duration 0 25 Maximum Power 10 Frequency fi 03 Hz Assembly eters and Heater Statu u Temperature 400 K Thermometer A 47 58 ohm Thermometer B 46 75 ohm 815 8 ohm sec uw Heater Heater resistance 815 8 Ohm Please verify that the heater resistance reading is as expected for 300 K Heater tests OK Setting up User Bridge for calibration All Tests OK Starting calibration Setting temperature to 400 K Waiting for system stability System is stable waiting for equilibrium Pause Figure 2 10 Thermal Transport Calibr 2 10 PPMS Thermal Transport Option ate Thermometers and Heater Wizard User s Manual Quantum Design C H APTER 3 Software 3 1 Introduction This chapter contains the following information e Section 3 2 presents an over
81. n Boltzmann constant The factor of in the equation is due to the approxima tion that only half of the sample surface area is radiating at the hot temperature while the other half is at the cold temperature Since radiative heat losses are often very difficult to accurately estimate you should expect errors in measurements of thermal conductance above T 300 K that are on the order of 1 mW K Correcting for Seebeck Coefficient of Manganin Leads The manganin leads that connect the shoes to the connector plugs have a small Seebeck coefficient no more than 1 uV K at any temperature and this has been estimated and subtracted from the Seebeck Coef uV K data column in the data file However the column Seebeck Volt uV is uncorrected Start up Checklist for Secondary Installation 1 Verify that the new AC board with the waveROM EPROM is installed in the Model 6000 PPMS Controller Refer to Sections 2 2 4 and 2 2 4 1 2 Verify that the Resistivity option Model P400 is installed and the user bridge board is in the Model 6000 PPMS Controller 3 Verify that all proper connections are made between the Model 6000 PPMS Controller and the Model 7100 AC Transport Controller Refer to Figure A 1 4 Verify that the High Vacuum option Model P640 is installed and activated 5 Verify that the gray Lemo cable for the Thermal Transport option is properly connected 6 Verify that the TTO software is installed as a PPMS MultiVu
82. n User s Manual for resistivity settings Single Measurement Mode The parameters for single mode are generally simpler than the parameters for continuous mode Basically you fix the heater power and set a heater on off criterion that depends on the style of measurement In stability mode the criterion is the temperature stability on both the hot and cold thermometer probes In timed mode you set a period length for the heater pulse that can be as long as desired Finally for Seebeck voltage you enter an estimate of the change in thermal voltage in uV that you expect from the sample during the measurement This determines the gain settings on the DSP circuitry in the AC Transport controller PPMS Thermal Transport Option User s Manual Quantum Design Chapter 5 Measurements 5 4 Section 5 4 Description of Measurement Process Description of Measurement Process With the TTO system you can measure thermal properties in either continuous mode or single mode The conceptual distinction between the two is that in continuous mode the system is constantly measuring the thermal properties and any acceptable data is saved to the data file while in single mode the system takes a measurement only when you request that it do so An advantage of the continuous technique is that a higher density of data is obtained and you take advantage of the adaptive algorithms built into the software which are constantly optimizing the system parameters for
83. nt and epoxy the leads and cure them appropriately Measure the Sample Dimensions 1 Measure the length between the hot and cold thermometer probes as well as the cross sectional area A of the sample in the region between these probes Calculate the total surface area of the sample and leads as well as an estimate of the sample s infrared emissivity This is necessary only for thermal conductivity measurements where some heater power is lost at high T gt 300 K to radiative thermal conduction from the hot end of the sample to the surrounding isothermal shield If the infrared emissivity of the sample is not known you can often employ these crude approximations e For nonmetallic surfaces for example ceramics and heavily oxidized metals e 1 e For unpolished metallic surfaces amp 0 3 For highly polished metallic surfaces 0 1 If thermal radiation from the sample is a concern you can minimize it by reducing the sample surface area or coating the sample with a thin film of known emissivity such as varnish assuming this does not affect other physical properties of interest to you The infrared emissivities of several substances for example some metals oxides and paints are tabulated in the CRC Handbook of Chemistry and Physics An artifact from thermal radiation can be seen as T tail in the thermal conductance that is visible at temperatures above 200 K Radiation from the sample and the shoe assem
84. nter or b select Instrument Chamber HiVac in the main PPMS MultiVu interface Wait for the HiVac state to be reached before starting thermal transport measurements because a significant heat leak can result from gas thermal conduction away from the TTO heater Quantum Design PPMS Thermal Transport Option User s Manual 5 3 Section 5 2 Chapter 5 Taking Thermal Transport Measurements Measurements 5 2 6 Open the Data File 1 Select the Data File tab in the Thermal Transport control center Figure 3 3 The tab indicates which data files are selected to save the measurement data If you run the measurement when no data file is selected the data is discarded 2 Click Browse to select a different file or create a new file Browse opens the Thermal Transport Select Data File dialog box which lists all existing files 3 Select a data file or enter the name of a new file When you create a file the software prompts you to define the sample properties for the sample whose measurement data will be saved to the file and the data entry fields in the control center s Sample tab are enabled Define the sample properties and then select OK As soon as you select or create a file the Data File tab appears again and the File Name field identifies the data file you have selected Notice that by default the Capture Raw Data check box is not selected If this box is enabled raw measurement data is saved to a raw data file that has the same nam
85. ockets on Thermal Transport Sample Puck C 3 iv PPMS Thermal Transport Option User s Manual Quantum Design Contents Tables Table 1 1 Table 1 2 Table 1 3 Table 1 4 Table 2 1 Table 3 1 Table 3 2 Table 3 3 Table 4 1 Table 4 2 Table 5 1 Table 5 2 Table 5 3 Table B 1 Table B 2 Table C 1 Quantum Design Table of Tables System Requirements for the Thermal Transport System eese nennen 1 2 Thermal Transport System Parameters essere nennen eene retener 1 2 Thermal Transport System Components essere nennen nennen een rennen trennen 1 2 Styles for Measurements Taken in Single Measurement Mode essere 1 4 Recommended Sample Parameters for Nickel Calibration Samples eee 2 5 PPMS System Data Items That Can Be Saved to the TTO Measurement Data File 3 9 Fields in Thermal Transport Measurement Data File essere 3 11 Fields in Thermal Transport Raw File ener rennen nennen enne 3 13 Sample Geometries and Range of Measurable Thermal Conductivities ess 4 2 Approximate Thermal Conductance of EpOxies cccssssssscseeeecsseeecesecatesecaeesecnaeeceecneeeeceaeeeeeseeeeeeaees 4 5 Minimum and Maximum Parameter Limits for Continuous Mode Measurements 5 6 General Settings for Continuous Mode Measurement
86. oing measurement and summarizes the results of the last measurement Color coded warning and error messages in the Status bar alert you to possible problems Warning messages appear on a yellow background Error messages appear on a red background The Waveform tab in the Thermal Transport control center Figure 3 5 displays raw data waveforms and curve fits for any of the measurements and the tab indicates the fitting parameters of signal amplitude time constant x where relevant and the residual for the fit The measurement Progress bar and countdown timer in the bottom right corner of the Thermal Transport Measurement dialog box indicate the time remaining before the measurement is complete Refer to Figure 3 7 In the Progress bar yellow indicates the heater on state while blue indicates off The right side of the Thermal Transport Measurement dialog box summarizes the most recent measurement and the parameters period and power used for the current measurement Refer to Figure 3 8 Note that if the cursor is placed over the displayed results a ToolTip shows the estimated error for the results The Thermal Transport Log window Figure 3 1 keeps a record of all messages that appear in the Thermal Transport control center Status bar The TTO status log is saved in the file TtoLog txt which is in the directory C OdPpms ThermalTransport LogFiles PPMS Thermal Transport Option User s Manual 3 9 Section 3 4 Chapter 3 Therma
87. ontrol Center Waveform Tab Clicking the right mouse button inside the graph window in the Waveform tab opens a menu that allows selection of thermal conductivity Seebeck coefficient or resistivity results and whether to plot the fitted curve along with raw data The title of the graph indicates which data is being displayed For thermal conductivity data Temperature Delta refers to the difference between hot and cold thermometers while for Seebeck measurements Seebeck Voltage refers to the voltage difference between the hot and cold shoes To the right of the graph are listed three parameters that briefly summarize the curve fitting results the total amplitude obtained by the curve fitting routine equivalent to Delta Temp or Seebeck Volt in the data file the long time constant in the measurement that is t this is not relevant to resistivity data and the residual of the curve fit that is the error estimate for the reported total amplitude Section 1 5 contains more information on the AC measurements and error estimation in TTO data In the Waveform tab you can also zoom to examine details of the data by dragging the mouse from the upper left to the lower right corner of the graph while holding down the left mouse button To zoom out drag the mouse in the opposite direction while holding down the button or select Zoom All in the pull down menu which is accessed by clicking the right mouse button in the graph PPMS The
88. option Quantum Design PPMS Thermal Transport Option User s Manual 1 1 1 C H A P T ER 2 Hardware 2 1 Introduction This chapter contains the following information 2 2 Thermal Transport Hardware Section 2 2 discusses and illustrates the TTO hardware Section 2 3 discusses the ACT option hardware that is used with TTO The TTO hardware includes the following Thermal Transport sample puck Isothermal radiation shield tube and cap Two calibrated plug in thermometer shoes One calibrated plug in heater shoe Section 2 4 discusses the High Vacuum option hardware that is used with TTO Section 2 5 explains how to calibrate new shoe assemblies Three uncalibrated shoes two thermometer shoes and one heater shoe User s kit Two nickel calibration samples Thermal Transport connection cable The TTO system also uses ACT hardware Section 2 3 High Vacuum hardware Section 2 4 and if required an AC board ROM upgrade kit Quantum Design PPMS Thermal Transport Option User s Manual 2 1 Section 2 2 Thermal Transport Hardware 2 2 1 CAUTION Thermal Transport Sample Puck The Thermal Transport sample puck Figure 2 1 plugs into the 12 pin socket at the bottom of the PPMS sample chamber The Thermal Transport puck is inserted into the sample chamber by using the standard PPMS puck extraction tool part number 4084 110 All 12 pins on the puck are used for thermal transport measurements Appendix C lis
89. ort Measurement nmn Period Power fi oo w Temp Rise Seebeck Voltage Period Ratio EN Last Measuremen Curent Measuremeni 15 x Temp 304 09 kK Field 70000 Oe Conduct 118 87 W K m Seebeck 39 873 WK Period 80 98 sec Power 29 2 mit 80 98 sec pas mw Period Power Stop Pause Close Help Progress 50 sec ia Figure 3 8 Thermal Tab in Thermal Transport Measurement Dialog Box PPMS Thermal Transport Option User s Manual Quantum Design Chapter 3 Software Due to the complexity of making an adaptive resistivity measurement a separate tab is devoted to resistivity Figure 3 9 so that you can have maximum freedom in setting limits such as min max excitation and min max frequency as well as measurement duration The measurement excitation Section 3 3 Thermal Transport Control Center frequency is allowed to vary so that a 90 resistive that is in phase signal is obtained Autoranging parameters may also be changed with the default being Sticky Autorange Changes made in this tab are saved only if the Set button in the tab is selected See the Physical Property Measurement System AC Transport Option User s Manual for more information on resistivity measurement parameters Thermal Transport Measurement Settings Thermal Limits and Setting Min Max Excitation 0 1 1 m Frequency 1
90. riate to TTO and hence the modeling was done differently Estimating Errors in the Data The software also estimates the standard deviations c in the reported quantities of thermal conductivity Seebeck coefficient electrical resistivity and figure of merit ZT This is done by estimating the goodness of the curve fits to x a and p by calculating the residual of the curve fit We make the assumption that this residual reflects the error in our estimate of the quantity DT or DV and this is true when the data deviates from the curve fit in a random manner If deviations are systematic as can be seen by inspecting the data in the raw file this indicates that the curve fit does not properly represent the data and the quantity and that error estimates are incorrect If this occurs consult Chapter 6 for troubleshooting tips The residual for the AT vs time curve fitting is calculated as follows X aT AT model y Residual R 4 x Equation 1 3 where N is the number of data points making up the curve In the measurements of and a N 64 while for p N 128 Since the thermal conductance K P AT errors in the heater power P see the next section must also be taken into account The standard deviation in the conductivity is then calculated 2 2 2 2 Monee E m i e Seas Equation 1 4 Maldonado O Pulse method for simultaneous measurement of electric thermopower and heat conductivity at low temperatur
91. rmal Transport Option User s Manual Quantum Design Chapter 3 Software 3 3 2 Section 3 3 Thermal Transport Control Center Thermal Transport SIM nickel dat E iol x The Advanced tab includes a software wizard that allows Install Data File Sample Waveform f you to calibrate new TTO shoe Test Heater Calibrate cana ee A D thermometers 1n the Excitation D ma Start The calibration fixture 3084 576 from the user s kit is used Vid lir Restart in conjunction with this Heater Off o software wizard The Restart button is used if you previously cancelled a calibration and want to restart Refer to Section 2 5 for more Status Measure Help information on calibrating shoe Acquiring Thermodata at 288 3K 70000 00e Sona Settings Swap Thermometers Figure 3 6 Control Center Advanced Tab Other features on the Advanced tab include a heater test in which you select the desired heater current to apply as well as an option to swap the software s assignment of hot and cold thermometers Measurement Menu Selecting the Measure button at the bottom of the Thermal Transport control center opens the Thermal Transport Measurement dialog box which allows you to run immediate mode TTO measurements without having to write a sequence file Three tabs Settings Thermal and Resistivity shown in Figures 3 7 3 8 and 3 9 are immediately visible in the Thermal Tran
92. s that a new waveform table that of a square wave pulse be added to this library All new AC boards include this new waveROM chip but some customers with older boards must install the new chip in order to use the TTO system If you are one of these customers a new waveROM and a PLCC chip extraction tool AC board ROM upgrade kit have been sent to you so that you can swap out the old chip for the new one Refer to Section 2 2 4 1 MODEL 6000 REAR PANEL REAR PANEL OR N SCREWS CPU BOARD EN UA E om om 7 SYSTEM BRIDGE ACMS BOARD BOARD j o o N RESISTANCE BRIDGE USER BRIDGE BOARD d H p MOTHERBOARD GRE 3 WAVE ROM on j d Es 8 H i ol A SOLENOIDS won dalli LLL o ea t g P nu o Ke Et e J4 POWER J3 RIBBON CONNECTOR CONNECTOR Figure 2 4 WaveROM EPROM on AC Board in Model 6000 PPMS Controller Quantum Design PPMS Thermal Transport Option User s Manual 2 5 Sectio
93. se of the finger spreader When all fingers touch the base of the spreader the spreader evenly applies radial force to the fingers pushing them outward and slightly beyond their optimal location Remove the puck from the finger spreader Place the puck inside the finger contractor Refer to Figure 7 1 Press straight down on the puck and continue pressing until you press the puck completely into the finger contractor When the entire chuck is in the contractor the contractor evenly applies force to the outside of the fingers pushing them inward The contractor pushes the fingers regardless of external wear or variations on the puck so that the fingers obtain their optimal location 5 Remove the puck from the finger contractor Place the puck inside the test cutout Refer to Figure 7 1 Verify that the puck fits easily but snugly in the test cutout Greasing the Puck Fingers and the Coldfoot Clamp The thermal contact between the sample puck and the heater block can be further improved by applying a small amount of H Grease which is included in the TTO user s kit to the puck fingers You may also wish to use a small amount of H Grease on the sample s cold lead when clamping it in the coldfoot because this contact can be a significant thermal resistance Note that it is always important to apply enough tension to the coldfoot screw in order to have good thermal and electrical contact between the sample lead and the coldfoot PPMS T
94. sign Chapter 6 Section 6 4 Troubleshooting High Vacuum Problems 6 3 Thermal Radiation Tail in the Thermal Conductivity Data Thermal radiation between the sample and shoe assemblies and the surrounding environment introduces errors in the measurement of thermal conductivity at high temperatures Some of the heat produced by the heater resistor radiates instead of traveling through the sample in accordance with the radiation law described in Section 1 5 5 The resulting tail has a T temperature dependence that is generally observable only above about 200 K Described here are some ways of minimizing errors due to radiation effects You may try one or more of these techniques in order to manage thermal radiation in your measurements 1 Increase the geometrical factor of the sample A so as to make the thermal conductance of the sample much higher than the errors associated with subtracting the radiation thermal conductance These errors are about 1 mW K at the highest temperatures 2 Minimize errors in estimating sample radiation by coating the surface of the sample with a material of known emissivity or by choosing a sample geometry minimizing the radiation surface area 3 Modify the mounting of leads on the sample by thermally sinking the heater and hot thermometer shoes together and connect only the heater to a lead on the sample The shoes can be affixed to each other by using H Grease to stick them together back to back an
95. sport Measurement dialog In the Settings tab Figure 3 7 you determine basic settings for all measurements First you select which of the four thermal transport quantities are to be measured Note that checking Figure of Merit ZT automatically selects all measurements because they are all required to assess ZT You have the option to save marginal results which would otherwise be discarded to the data file Marginal measurements are defined as those for which the software was able to determine a quantity but the regression errors of the curve fits were between 50 and 200 the measurement is considered failed if the regression is higher than 200 The Discard First N Results check box is included because the first several measurements often have large errors due to the measurement parameters not being optimized Choosing N 3 is typically adequate if you choose to discard any results In the Next Measurement box you can specify the period and heater power for the next thermal measurement cycle even after measurements have started Note that any changes made in this box are saved only if the Set button is selected Selecting Clear restores the values that were last input Quantum Design PPMS Thermal Transport Option User s Manual 3 5 Section 3 3 Thermal Transport Control Center Figure 3 7 Settings Tab in Thermal Transport Measurement Dialog Box Thermal Transport Measurement Thermal Resistivity gt Last Mea
96. ssed in percent of can be decreased in order to minimize uncertainty in absolute temperature temperature during a pulse such as in cases where Heater power is adaptively physical properties are changing very rapidly with adjusted to achieve the temperature Errors in data increase sharply if Temp desired Temp Rise Rise lt 1 is chosen due to small magnitude of thermal signal Seebeck Determines initial gain Entering an expected maximum value determines Voltage settings in uV for DSP initial gain settings for DSP voltage readback preamp Software uses sticky autorange algorithm to rescale preamp if initial guess was far off Period Ratio Provides feedback for heater period Defined as ratio of the period to long time constant taul of sample Default period ratio value of 8 has been found empirically to be near minimum needed by curve fitting algorithm in order to converge on correct result Table 5 2 General Settings for Continuous Mode Measurements PARAMETER FUNCTION Save Marginal Results Prompts software to write to data file results for which fitting algorithm was able to converge on a value but encountered significant errors from one or more sources Results are deemed marginal if the error on the curve fit is between 50 and 200 Discard First N Results Prompts software to discard user specified number of first results This setting is useful because first several 3
97. standard deviation in the figure of merit ZT is obtained by propagating the errors from each of the measurements 2 2 2 2 o ZT ZTx m 4 ES 4 an p Equation 1 8 K P where the last term is the standard deviation of the sample temperature over the measurement 1 10 PPMS Thermal Transport Option User s Manual Quantum Design Chapter 1 Introduction 1 5 5 1 5 6 1 6 Section 1 6 Start up Checklist for Secondary Installation Correcting for Heat Loss Thermal conductance is determined as K P AT where P is the heat flowing through the sample Since the heat flux cannot be measured directly the net conducted heat through the sample is estimated as the power I R dissipated in the heater resistor minus losses due to radiation or thermal conduction down the leads from the shoe assemblies Thus the conductance is determined as follows K W K TR a Prad AT Ksnoes Equation 1 9 where K shoes aT bT RE cT Equation 1 10 is a standard estimate of the thermal conductance of the shoe assemblies a b and c are constants and Pred or X S 2 x x Tha Toa Equation 1 11 is the radiation from the sample S is the total sample surface area is the infrared emissivity of the radiating surface see Section 5 2 2 for more information on estimating the emissivity Thovcoia are the average temperatures of the hot and cold thermometers during the measurement and or 5 67 x 10 W m K is the Stefa
98. t room temperature you can set a target temperature of 1 8 K and a slew rate of 0 5 K min If you are taking single steady state measurements these are obviously taken at a fixed temperature and field This method is more amenable to the Scan Temperature command which allows you to wait for system stability at each target before taking a measurement Quantum Design PPMS Thermal Transport Option User s Manual 5 5 Section 5 3 Chapter 5 Measurement Mode Parameters Measurements 5 3 Measurement Mode Parameters 5 3 1 Continuous Measurement Mode Parameters for continuous mode measurements are defined in the Thermal tab in the Thermal Transport Measurement dialog box You open this dialog box by selecting the Measure button in the Thermal Transport control center Thermal Transport Measurement 2 5 x Settings i Resistivity _4 gt p Last Measurement 1 r Settings and Limits Temp 304 03 K Min Max Field 70000 Oe Period 30 30 sec Conduct 118 87 W K m Power 0 001 50 mW Seebeck 53673 wK Temp Rise 3 4 Resit Ohm m Vago om a m Bm sec Ratio f Power 29 2 mw Current Measurement Period 80 98 sec Set Clear Power 29 8 mw Progress stop Pause Chose Hep 50s fo Figure 5 1 Thermal Tab in Thermal Transport Measurement Dialog Box The Clear button in the Thermal tab restores either the values that were in memory after the last time
99. te e ron re RH ten p Fe ERR SEET EERTSE BRA 4 6 CHAPTER 5 Measurements 54 eedem tte dete deti d deti 5 1 5 1 Introduction ssir X 5 1 5 2 Taking Thermal Transport Measurements sess enne enne nnne tnr nns 5 1 5 2 1 Connect Leads to the Sample eee tec oe eet ERR pe ete pe EEEN EE epe abo epe ereptus 5 2 5 22 Measure th Sample Dimensions erc net oceano te elsi aera ee pere ae ceo alee 5 2 5 2 3 Mount the Sample eet e E SI RETE TERRI DE E EE OR EROR ce bete bua Sk ERI rec oen creo cesa 5 3 3 24 Install the Sample e emeret er RI oe Eee Ret beoe SUERTE OE ESE 5 3 5 2 5 Start the Hhgh Vacu m System sais 2 rete AI ree Pete Seres e Ra Prisa see EE reae date sE ete eger oet 5 3 522 6 Open the Data File oerte tte beet tee epe ee ree reu 5 4 5 2 7 Define the Measurement eene teet me treten cite ege e 5 4 25 2 8 R n the Measurement eon aio et tie ie ere Ree ERE Eee ERUIT MORE a er lets 5 5 5 2 8 1 Running the Measurement Interactively eeeeeeeeseeeeeee nennen nnne enne nennen ener enne 5 5 5 2 8 2 Running the Measurement in a Sequence eeeeeeseeeeeeeeeeeeen nennen enne 5 5 5 2 9 Scanning or Ramping the Temperature While Measuring 5 5 u PPMS Thermal Transport Option User s Manual Quantum Design Contents Table of Contents 2 3 Measurement Mode Param eters ier eR e ete te Re ibe pants shee cose horse n epeei
100. the AC board The AC board includes a DSP digital to analog converter DAC current drivers and other control electronics that are necessary to synthesize excitation signals and process sample response signals The DSP provides the excitation waveform and processes the sample signal Quantum Design PPMS Thermal Transport Option User s Manual 2 7 Section 2 4 Chapter 2 High Vacuum Hardware Hardware 2 4 High Vacuum Hardware The High Vacuum option which operates in conjunction with the TTO system reduces the amount of gas in the sample chamber and thus minimizes stray thermal conduction from the heated sample The TTO system works with either the Turbo Pump High Vacuum option or the Cryopump High Vacuum option The details of the Turbo Pump and Cryopump high vacuum systems are contained in the Physical Property Measurement System Turbo Pump High Vacuum Option User s Manual and Physical Property Measurement System Cryopump High Vacuum Option User s Manual respectively 2 4 1 Contact Baffle An integral part of either the Turbo Pump or the Cryopump High Vacuum system is the contact baffle assembly The contact baffle makes thermal contact with the isothermal region of the sample chamber which is just above the puck The thermal contact between the contact baffle and the isothermal region helps create a more uniform thermal environment for the puck by causing the contact baffle to be at the same temperature as the chamber walls that are ne
101. the hot and cold sample thermometers and the system thermometer see the raw data file was linear and not irregular Check the value for the period of thermal measurements in the vicinity of the gap because a very long period results in lower density of data Look in the TTO Error Count and TTO Status Log dialogs for evidence of errors Also check the codes for both the PPMS Status and TTO Error status in the data file and consult Appendix B to interpret the codes Steps in the Data If the data jumps in a step wise fashion as a function of temperature or field do the following Check to see if the jump exists only in the magnitudes of thermal conductance and electrical resistance but is absent in Seebeck coefficient data This is evidence that the sample geometry AA has changed due to internal cracking of the sample this can often occur under temperature cycling or breaking of the epoxy bonds to the leads Weak epoxy bonds are evidence of poor epoxy strength or poor thermal matching of the epoxy and the sample Look at the standard deviation in the measured quantities and also at the raw data to see if the software is adequately modeling the data A step in the data can occur when the data fitting is poor enough that several distinct solutions have comparable curve fit errors See the Error column in the dat file and consult Appendix B to interpret the TTO status code PPMS Thermal Transport Option User s Manual Quantum De
102. the serial numbers of each of the three shoe assemblies These numbers are handwritten on one side of the connector plug at the puck While attaching the shoes use care not to pull on the thin wires running to the probe shoes and avoid scratching the areas near solder pads especially where the wire is soldered to the back wall of a shoe 4 Check carefully that neither the shoes nor their wires are touching each other or any part of the puck and that the sample is contacting the puck only at the clamp of the coldfoot 5 Place the radiation shield on the puck remove the shield cap and inspect to verify that no wires shoes or that the sample touches the shield 6 Replace the shield cap before you insert the sample into the PPMS probe Install the Sample 1 Activate the Thermal Transport option if the option is not currently active Do the following a select Utilities Activate Option in the PPMS MultiVu interface b click on Thermal Transport under the Available Options heading and then c select Activate 2 Select the Install tab in the Thermal Transport control center Figure 3 2 3 Select Install Wizard and follow the software prompts to install the sample in the PPMS sample chamber Start the High Vacuum System If the install wizard did not start the high vacuum system you start the high vacuum system by doing one of the following either a select the HiVac button in the Install tab in the Thermal Transport control ce
103. to the sample are configured to minimize cross talk between the excitation signal the P1 port on the Model 7100 and the detected signal the P5 port on the Model 7100 In addition each pair is individually twisted in the gray Lemo cable and also in the wiring between the puck base and the sample The exceptions to this are the I leads and the V leads between the five pin connector plugs and the sample recall that V and V run to separate shoe assemblies so they are physically separated at this point Table C 1 on the following page lists all TTO sample connections Figure C 1 illustrates the sample connections and Figure C 2 illustrates the pinout of the connector sockets on the Thermal Transport sample puck Quantum Design PPMS Thermal Transport Option User s Manual C 1 Section C 2 Appendix C Thermal Transport Pinouts Pinout Tables Table C 1 TTO Sample Connections SAMPLE PUCK GREY P1 PORT ON P5 PORT ON P1 USER PORT ON FUNCTION SYMBOL LEMO MODEL 7100 MODEL 7100 MODEL 6000 Current thermometers Imt 3 5 7 Current thermometers In 4 18 20 Current heater Q 5 1 Current heater Q 6 6 Voltage cold thermometer Va 7 8 Voltage cold thermometer Vin 8 21 Voltage warm thermometer Vin 9 6 Voltage warm thermometer Nat 10 19 Current sample I 11 2 Current sample I 12 7 Voltage sample V 13
104. trical resistivity because these individual quantities may be more accurately measured by using excitation currents and temperature differentials optimized for each situation Limits for the param eters defining each measurement may be specified prior to running the measurement Section 5 3 discusses the measurement parameters Each measured thermal transport property may be determined in either of the two measurement modes continuous or single supported by the TTO system refer to Section 1 3 You select a measurement mode and then you select the thermal properties to measure in that mode Thermal Conductivity The TTO system measures thermal conductivity x by applying heat from the heater shoe in order to create a user specified temperature differential between the two thermometer shoes The TTO system dynamically models the thermal response of the sample to the low frequency square wave heat pulse thus expediting data acquisition TTO can then calculate thermal conductivity directly from the applied heater power resulting AT and sample geometry Seebeck Coefficient The TTO system determines the Seebeck coefficient also called the thermopower o by creating a specified temperature drop between the two thermometer shoes just as it does to measure thermal conductivity However for Seebeck coefficient the voltage drop created between the thermometer shoes is also monitored The additional voltage sense leads on these thermometer shoes are
105. ts pinouts The puck serial number is written on the plastic socket of the base Modularized shoe assemblies including two temperature voltage shoes and one heater current shoe on the Thermal Transport puck connect to the three five pin sockets on the green printed circuit board Each gold plated copper shoe has a hole in which the appropriate sample lead is inserted and held in the shoe by a small stainless steel metric M1 screw The temperature voltage shoe assemblies contain a Cernox 1050 thermometer as well as a voltage lead that is soldered to the shoe itself The heater current shoe assembly contains a resistive heater chip as well as an electrical current source lead I that is soldered to the shoe At the other end of each shoe assembly is a five pin electrical plug on which the serial number is written Each shoe type heater or thermometer is individually serialized The 2 inch long 0 003 inch diameter wires used for leads on the shoe assemblies are designed to minimize thermal conduction from the sample to the puck and hence all are made of manganin alloy with the exception of the current I lead which is made of PD 135 low resistance copper alloy Two Sharpie permanent markers red and blue have been included with the TTO system so that you can color the alumina Cernox chip housing on each thermometer shoe as well as the plastic electrical plug at the other end to indicate the hot and cold probes Marking the housing is con
106. uck eeeesseseeeeeeeeeeeeene nennen nennen enne te nnne ene etre enne nn 2 3 Figure 2 3 Thermal Transport Option User s Kit eene enne nennen nee nennen enne 2 4 Figure 2 4 WaveROM EPROM on AC Board in Model 6000 PPMS Controller eee 2 5 Figure 2 5 Thermal Transport Connection Cable eese nennen nennen enne nre nre nn enne 2 6 Figure 2 6 Front Panel on Model 7100 AC Transport Controller eese nennen 2 7 Figure 2 7 Baffle Assembly with Contact Baffle essent nete enn enne 2 8 Figure 2 8 Close up View of Contact Fingers and Charcoal Holder on Contact Baffle Assembly 2 8 Figure 2 9 Calibration Fixture Plugged into TTO Puck and Illustrating Sockets for Each Shoe Assembly 2 10 Figure 2 10 Thermal Transport Calibrate Thermometers and Heater Wizard eene 2 10 Figure 3 1 Thermal Transport Log Window sees nennen nennen eene nr ennt enne nre enee trennen enne 3 2 Figure 3 2 Control Center Install Tab 4 noit Tete d Ure pt dre 3 3 Fig re 3 3 Control Center Data File Tabiy node oed ecd ee e faded pe eicit e Pede rr ete dent 3 3 Figure 3 4 Control Center Sample Tab eese enne eene teen a SEEN Ea e R reete teen 3 4 Figure 3 5 Control Center Waveform Taborski eraen aspe eteeni ees enne nennen eene ne enne trennen ene i ripen oaee enne 3 4 Figure 3 6 Control Center
107. venient because it is easy to confuse the two sets of wires between the sockets and the shoes The sides of the Chapter 2 Hardware d dei to NAR JA hy Mf ie i amp N NS AWE V Ml il UN Figure 2 1 TTO Puck with Radiation Shield sockets for the thermometer shoe assemblies are painted so that the middle socket is red hot probe and the left side socket is blue cold probe The right hand socket which is unpainted is used only by the heater shoe assembly The sample is connected to the puck at the coldfoot which contains a Phillips screw and a stainless steel clamp on the bottom that clamps onto the sample lead This is the thermal sink for the sample so good thermal contact is important here If achieving good thermal contact is a concern a small amount of Apiezon H Grease which is included in the TTO user s kit Section 2 2 2 can be used on the sample lead to improve contact to the coldfoot Note that good electrical contact is also required at the coldfoot if resistivity measurements are being made The copper isothermal radiation shield screws into the base of the puck and is designed to minimize radiation between the sample and the environment The cap is removable so that you can verify that the leads and the sample do not touch the shield A copper shield plate is also placed between the sample stage and the PC board sockets to minimize radiation effects Use care when threading the radiation shiel
108. view e Section 3 4 discusses the TTO data of the TTO system software files e Section 3 3 discusses the Thermal e Section 3 5 explains how to examine Transport control center data saved to a TTO data file 3 2 Overview of Thermal Transport Software The TTO software module is integrated into the Quantum Design PPMS MultiVu environment Version 1 1 6 or greater of the PPMS MultiVu software is required to install the TTO software For software installation instructions see Appendix A TTO is designed to be used by both experts and newcomers to the study of thermal transport properties To accommodate this spectrum of users the software interface is multi leveled so that beginners can easily set up and perform measurements at the top level while experts can choose to navigate into submenus in order to adjust various parameters or customize measurements TTO measurements can be run either interactively at the dialog or in a sequence program While the TTO software is active in PPMS MultiVu the command TTO Measure appears in the sequence command bar under the Measurement Commands heading This command is used to start stop or change measurement parameters within a sequence file Users who are familiar with measurement sequence commands for other Quantum Design options will find an important difference in the use of the TTO Measure command compared to other options where sequence execution is typically paused until a measurement command is co
109. with electrical resistivity p the thermal conductivity and Seebeck coefficient also provide a measure of the so called thermoelectric figure of merit Z p which is a quantity of practical significance because it quantifies a material s ability to transport heat by the application of an electric current Peltier effect or conversely a material s ability to generate an electric field by passing a thermal current Seebeck effect described above The figure of merit is usually expressed as the dimensionless quantity Z x T where Z x T 1 is a common benchmark for viability of a material for thermoelectric applications Measurement Modes The TTO system includes two measurement modes Continuous measurement mode e Single measurement mode All properties measurements offered by TTO can be performed in either of these two modes Parameters for each measurement mode see Section 5 3 may be specified prior to running any measurement in that mode Continuous Measurement Mode In continuous measurement mode measurements are being taken continually and the adaptive software is adjusting parameters such as heater power and period to optimize the measurements This mode is amenable to slow sweeps of system variables such as temperature or magnetic field and it is often the most rapid way of obtaining data because you do not have to wait for the system to reach equilibrium before measuring The continuous mode is also expedited by

PPMS TTO Manual - Materials Research Laboratory at UCSB

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