JP2017040556A - Sample support, electrothermal characteristic evaluation device, method of evaluating electrothermal characteristic, and method of evaluating electrode - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a sample support for measuring electrothermal characteristics with high precision without depending upon the size of a sample to be measured, an electrothermal characteristic evaluation device using the same, a method of evaluating electrothermal characteristics using the same, and a method of evaluating an electrode.SOLUTION: A sample support according to the present invention comprises first/second blocks having first/second thermocouples insulated except tips thereof embedded, and the first/second blocks hold a sample therebetween with the tips of the first/second thermocouples in contact with the sample. A space between the first thermocouple and first block except a region where the first thermocouple comes into contact with the sample, and a space between the second thermocouple and second block except a region where the second thermocouple comes into contact with the sample are filled with a material having conductivity, and the first/second thermocouples extend out of plane-directional ends of the first/second blocks so as to be connected to a voltmeter.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a sample stage, a thermoelectric property evaluation apparatus, a method for evaluating thermoelectric properties, and a method for evaluating electrodes.

  Thermoelectric conversion technology that can convert thermal energy directly into electrical energy has attracted attention. In particular, due to recent developments in sensing technology and wireless technology, application of thermoelectric conversion technology in low output regions such as “nW” and “μW” is expected. Therefore, a thermoelectric conversion material (also referred to as a thermoelectric material) that generates electricity due to a temperature difference at the material edge has various thicknesses from a bulk shape to a film shape. A technique for evaluating the thermoelectric characteristics of such a thermoelectric material has been developed (for example, Patent Document 1).

  FIG. 34 is a schematic diagram of a conventional thermoelectric property evaluation apparatus.

  The thermoelectric property evaluation apparatus 1 shown in FIG. 34 is the same as that shown in FIG. According to Patent Document 1, the end surface Se of the measurement sample S is sandwiched between the first electrode 14 and the second electrode 15 and supported by the pair of blocks 11, a temperature gradient is formed in the measurement sample S, and the switch 18 is opened. The thermoelectric power of the measurement sample S is calculated based on the thermoelectromotive force of the measurement sample S measured by the voltage measurement means 16 in the state and the temperature difference of the end surface Se of the measurement sample S measured by the temperature measurement means 21 and 22; After generating the thermoelectromotive force of the measurement sample S, the switch 18 is closed and discharged, and the measurement sample is measured based on the voltage drop of the measurement sample S measured by the voltage measurement means 16 and the current value measured by the current measurement means 17. The resistivity of S can be calculated. In the measurement of the resistivity, since the discharge generated in a short time by closing the switch 18 using the thermoelectromotive force of the measurement sample S is used, it is not necessary to use a constant current power source capable of pulse energization. Accordingly, it is possible to realize highly accurate measurement of thermoelectric power and resistivity with a thermoelectric characteristic evaluation apparatus that is simpler and less expensive than the conventional apparatus.

  However, in the thermoelectric characteristic evaluation using the thermoelectric characteristic evaluation apparatus 1 of Patent Document 1, it is necessary to consider the resistance in each component, which not only makes the calculation complicated, but also cannot reduce errors. Moreover, in the thermoelectric characteristic evaluation apparatus 1 of Patent Document 1, although the thermocouples 21 and 22 have a structure in direct contact with the sample S through electrodes, the size of the measurement sample S is limited.

On the other hand, a dimensionless figure of merit ZT represented by the following formula is used for performance evaluation of thermoelectric materials, and ZT ≧ 1 is regarded as a standard for practical use.
ZT = S ² σT / k
Here, S is the absolute Seebeck coefficient, σ is the conductivity, T is the absolute temperature, and k is the thermal conductivity. Output, the temperature of both ends of the thermoelectric material is constant, depending on the S ² sigma, the S ² sigma called power factor.

  However, the accuracy of evaluation using the dimensionless figure of merit ZT is not sufficient, and considering a low output region such as “nW” or “μW”, development of a more accurate evaluation method is desired.

JP 2011-185697 A

  An object of the present invention is to provide a sample stage for measuring thermoelectric characteristics with high accuracy without depending on the size (height, cross-sectional area, etc.) of the sample to be measured, a thermoelectric characteristic device using the same, and a device using the same. A thermoelectric property evaluation method and an electrode evaluation method. The further subject of this invention is providing the method which can evaluate the figure of merit of a thermoelectric material with high precision.

A sample stage for sandwiching a sample according to the present invention and evaluating the thermoelectric characteristics of the sample includes a first block in which a first thermocouple having an insulating portion other than the tip is embedded, and a first block having an insulating portion other than the tip. A second block in which two thermocouples are embedded, wherein the first block and the second block have the tips of the first thermocouple and the second thermocouple, respectively. A space between the first thermocouple and the first block other than a region where the first thermocouple and the sample are in contact with each other, the second thermocouple and the sample are in contact with each other, and the second block The space between the second thermocouple and the second block other than the region where the thermocouple and the sample are in contact with each other is filled with a conductive material, and the first thermocouple is A planar end of the first block to be connected to a voltmeter And exits to the outside from the second thermocouple to be connected to the voltmeter, and exits to the outside from the end portion of the planar direction of the second block, thereby achieving the above-mentioned problems.
The material may satisfy an absolute value of an absolute Seebeck coefficient at room temperature of 0 μV / K or more and 20 μV / K or less.
The material is Au, Al, Ag, Co, Cr, Cu, Fe, In, Ir, Mg, Mo, Ni, Pd, Pt, Ru, Su, Ti, W, Zn, and at least one of them. It may be selected from the group consisting of containing alloys.
The material is at least one selected from the group consisting of Au, Al, Ag, Co, Cr, Cu, Fe, In, Ir, Mg, Mo, Ni, Pd, Pt, Ru, Su, Ti, W, and Zn. It may be an intermetallic compound containing a metal.
The first block and the second block may be made of a thermally conductive material having a thermal conductivity of 65 W / (m · K) or more at room temperature.
The first block and the second block are Au, Al, Ag, Co, Cr, Cu, Fe, In, Ir, Mg, Mo, Ni, Pd, Pt, Ru, Su, Ti, W, Zn And at least one of these alloys may be selected.
The first block and the second block are Au, Al, Ag, Co, Cr, Cu, Fe, In, Ir, Mg, Mo, Ni, Pd, Pt, Ru, Su, Ti, W, and Zn. It may be an intermetallic compound containing at least one metal selected from the group consisting of:
The first thermocouple and the second thermocouple may be in contact with a sample provided with an electrode.
The thickness of the electrode may be 400 nm or more.
It may be accommodated in an external heater.
The thermoelectric property evaluation apparatus according to the present invention sandwiches a sample, measures the potential difference between the sample, the above-described sample stage for evaluating the thermoelectric property of the sample, temperature gradient means for forming a temperature gradient in the sample, and the like. And the voltmeter is connected to the first thermocouple that is exposed to the outside from the planar end of the first block and from the planar end of the second block to the outside. It is connected to the second thermocouple that comes out, thereby achieving the above object.
The temperature gradient means includes a heating device provided on a side facing the sample of the first block, and a cooling device provided on a side facing the sample of the second block. And may be provided.
You may further provide the switch which opens and closes the voltage measurement circuit which consists of the said sample and the said voltmeter.
The power source may further include a power source for applying a current to the sample, and the power source may be connected via current terminals formed of conductive wires respectively wound around the first block and the second block.
The power supply further applies a current to the sample, and the power supply is installed between the first block and the heating device and between the second block and the cooling device, respectively. It may be connected via.
The current terminal may be made of a block around which a conducting wire is wound, and the block may be made of a heat conductive material having a thermal conductivity of 65 W / (m · K) or more at room temperature.
A thermoelectric property evaluation apparatus according to the present invention includes a sample table for holding a sample and evaluating the thermoelectric property of the sample, a voltmeter for measuring a potential difference between the samples, and a power source for applying a current to the sample. And the voltmeter exits to the outside from the first end of the first block in the planar direction, and from the end of the second block in the planar direction to the outside. The power source is connected to a second thermocouple, and the power source is connected to the first block and a current terminal made of a conductive wire wound around the second block. Achieve.
A thermoelectric property evaluation apparatus according to the present invention includes a sample table for holding a sample and evaluating the thermoelectric property of the sample, a voltmeter for measuring a potential difference between the samples, and a power source for applying a current to the sample. And the voltmeter exits to the outside from the first end of the first block in the planar direction, and from the end of the second block in the planar direction to the outside. The power source is connected to a second thermocouple, and the power source is on the side of the first block that faces the sample and the side of the second block that faces the sample. Each is connected via an installed current terminal, thereby achieving the above object.
The current terminal may be made of a block around which a conducting wire is wound, and the block may be made of a heat conductive material having a thermal conductivity of 65 W / (m · K) or more at room temperature.
The method for evaluating the thermoelectric characteristics of a sample using the above-described sample stage according to the present invention includes sandwiching a sample provided with an electrode between the first block and the second block, and applying a temperature gradient to the sample. Repeating the steps of forming, measuring the potential difference and the temperature difference between the samples generated by the formed temperature gradient, forming the temperature gradient, and measuring the potential difference and the temperature difference And calculating the absolute Seebeck coefficient based on the following equation and S = ∇E / ∇T + S _thermocouple (where S (μV / K) is the absolute Seebeck coefficient, and ∇T (K) and ∇E (.mu.V), respectively, the change and the potential difference change of the temperature difference between the sample obtained by the repeating step, S _{thermocouples} (μV / K), said first thermocouple Oyo Is a Seebeck coefficient of the material of the second thermocouple)
Thereby achieving the above-mentioned object.
The step of forming the temperature gradient and the step of measuring the potential difference and the temperature difference may be performed in the atmosphere, oxygen, vacuum, inert gas atmosphere or wet gas atmosphere.
The step of forming the temperature gradient, the step of measuring the potential difference, the step of repeating, and the step of calculating the absolute Seebeck coefficient are repeated at least two or more for different temperatures, and obtained by the step of repeating the two or more. Plotting the absolute Seebeck coefficient against temperature and fitting, and the equation of the temperature dependence of the absolute Seebeck coefficient obtained by the fitting is integrated over the measured temperature range to calculate the open circuit voltage A step may be further included.
The method for evaluating the thermoelectric characteristics of a sample using the above-described sample stage according to the present invention includes sandwiching a sample provided with an electrode between the first block and the second block, and applying an electric current to the sample. A step of measuring a potential difference between samples to which the current is applied, a step of repeating the step of applying the current and the step of measuring the potential difference, and calculating an internal resistance of the sample based on the following equation: And R = ∇V / ∇I (where R is the internal resistance of the sample, ∇I (A) is the change in current value obtained in the repeating step, and ∇V is This is a change in potential difference between the samples obtained in the repeating step.)
Thereby achieving the above-mentioned object.
The step of applying the current and the step of measuring the potential difference may be performed in the air, oxygen, vacuum, inert gas atmosphere or wet gas atmosphere.
Step of calculating electric conductivity of the sample based on the following formula: σ = L / {(RR _{contact resistance} ) A} (where σ (S / cm) is the electric conductivity of the sample, L (cm) is the length of the sample, A (cm ² ) is the cross-sectional area of the sample, R (Ω) is the internal resistance of the sample, and R _{contact resistance} (Ω) is Resistance value between the sample and the electrode, resistance value of the material constituting the electrode, resistance value between the electrode and the first thermocouple, between the electrode and the second thermocouple Resistance value and the total resistance value of the materials constituting the first thermocouple and the second thermocouple)
May further be included.
The R _{contact resistance} (Ω) is a resistance value when the length of the sample is 0 when plotting a change in resistance value with respect to the length of the sample (provided that the cross-sectional area of the sample is constant). There may be.
Forming a temperature gradient in the sample; measuring a potential difference between the samples generated by the formed temperature gradient; calculating an effective maximum output of the sample based on the following equation: P _max = {(ΔE) ² × L} / {4 × R × A} (where P _max is the effective maximum output of the sample, and ΔE (μV) is obtained in the step of measuring the potential difference. The potential difference between the samples, L (cm) is the length of the sample, R (Ω) is the internal resistance of the sample, and A (cm ² ) is the cross-sectional area of the sample)
May further be included.
The sample is a module including one or more elements made of an n-type thermoelectric material and / or a p-type thermoelectric material, and a step of calculating the maximum output density of the sample based on the following formula: P _A = {(P _{max (n) + P max (} p)) × a} / (2 × L) ( where, _{P a} is the maximum power density of the _{sample, P max (n)} effective maximum of the n-type thermoelectric material Is the output, P _{max (p)} is the effective maximum output of the p-type thermoelectric material, a (%) is the filling rate of the n-type thermoelectric material and / or p-type thermoelectric material in the module, L (cm) is the length of the n-type thermoelectric material and / or p-type thermoelectric material)
May further be included.
A method for evaluating an electrode used for a thermoelectric material by using the above-described sample stage according to the present invention is a sample having different lengths made of a thermoelectric material provided with an electrode (however, the cross-sectional area of the sample is constant). ) Between the first block and the second block, applying a current to the sample, measuring a potential difference between the samples to which the current is applied, and applying the current And repeating the step of measuring the potential difference, calculating the resistance of the sample based on the following equation:
R = ∇V / ∇I (where R is the internal resistance of the sample, ∇I (A) is the change in current value obtained in the repeating step, and ∇V is the repeating step) (This is the change in the potential difference obtained in.)
Plotting the resistance against the length of the sample and reading the resistance when the length of the sample is zero, thereby solving the above-mentioned problems.

  In the sample stage according to the present invention, the first block and the second block sandwich the sample such that the tips of the first thermocouple and the second thermocouple are in contact with the sample. Furthermore, in the sample stage according to the present invention, the space between the first thermocouple and the first block other than the region where the first thermocouple and the sample are in contact, and the second thermocouple and the sample are in contact. A space between the second thermocouple and the second block other than the region is filled with a conductive material. As a result, the gap between the first / second thermocouple and the first / second block is eliminated and integrated, and the first and second thermocouples only need to contact the sample. / A sample having an arbitrary thickness and cross-sectional area can be measured without considering the size of the second block. Furthermore, since the electrode on the sample stage becomes unnecessary, the resistance of the electrode or the resistance between the electrode and the sample can be simplified, and the thermoelectric characteristics can be measured with high accuracy. In the sample stage according to the present invention, the first and second thermocouples are exposed to the outside from the end portions in the plane direction of the first and second blocks, respectively. Can do. As a result, the change in contact resistance is reduced, and the thermoelectric characteristics can be evaluated with high accuracy.

  A thermoelectric property evaluation apparatus according to the present invention includes the above-described sample stage, a temperature gradient unit, and a voltmeter, and the voltmeter is connected to the first thermocouple and the second thermocouple that have come out of the sample stage. Has been. As a result, various resistances such as contact resistance are simplified, and the absolute Seebeck coefficient can be calculated with high accuracy.

  A thermoelectric property evaluation apparatus according to the present invention includes the above-described sample stage, a voltmeter, and a power source, and the voltmeter is connected to a first thermocouple and a second thermocouple that are exposed to the outside from the sample stage. And the power source is connected through current terminals wound around the first block and the second block, respectively, or through current terminals installed in the first block and the second block, respectively. It is connected. As a result, various resistances such as contact resistance are simplified, so that internal resistance and electrical conductivity can be calculated with high accuracy.

  Furthermore, according to the thermoelectric characteristic evaluation method of the present invention, the fitting considering the temperature dependence of the absolute Seebeck coefficient is performed, so that the open circuit voltage can be obtained with higher accuracy. The open circuit voltage thus obtained is more accurate than that using the conventional dimensionless figure of merit ZT and is suitable for evaluating the figure of merit of thermoelectric materials.

Schematic diagram of the sample stage of the present invention Schematic diagram of thermocouple of the present invention Schematic diagram of thermoelectric property evaluation apparatus of the present invention Schematic diagram of a switch connected to the thermoelectric property evaluation apparatus of the present invention The figure which shows the equivalent circuit of the thermoelectric characteristic evaluation apparatus of this invention shown in FIG. 3, and the thermoelectric characteristic evaluation apparatus of a prior art Flowchart for evaluating absolute Seebeck coefficient as thermoelectric characteristics of a sample using the sample stage of the present invention Flow chart for evaluating an open circuit voltage as a thermoelectric characteristic of a sample using the sample stage of the present invention. Schematic diagram of thermoelectric property evaluation apparatus of the present invention Schematic diagram of another thermoelectric property evaluation apparatus of the present invention Flow chart for evaluating internal resistance and electrical conductivity as thermoelectric characteristics of a sample using the sample stage of the present invention Flowchart for calculating contact resistance using the sample stage of the present invention Schematic diagram of thermoelectric property evaluation apparatus of the present invention Schematic diagram of another thermoelectric property evaluation apparatus of the present invention Flow chart for evaluating effective maximum output as thermoelectric characteristics of a sample using the sample stage of the present invention The figure which shows the external appearance (A) and schematic diagram (B) of the thermoelectric characteristic evaluation apparatus comprised using the sample stand of this invention Appearance (A) and schematic diagram (B) of a gas replacement chamber containing the thermoelectric property evaluation apparatus shown in FIG. Schematic diagram of a conventional thermoelectric property evaluation device that measures the longitudinal direction The figure which shows the temperature difference dependence of the total thermoelectromotive force of Si wafer by Example 1. The figure which shows the temperature dependence of the absolute Seebeck coefficient of Ni plate by Example 2. It shows the appearance of the _Bi 2 Te ₃ nanowire array according to Example 3 It shows temperature and the heater output dependent temperature difference between both ends of the Bi ₂ Te ₃ nanowire array according to Example 3 It shows a temperature difference dependence of the thermal electromotive force of Bi ₂ Te ₃ nanowire array according to Example 3 Figure shows the temperature dependence of the absolute Seebeck coefficient of Bi ₂ Te ₃ nanowire array according to Example 3 The figure which shows the film thickness dependence of the electrical conductivity of Au The figure which shows the external appearance (A) and schematic diagram (B) of the thermoelectric characteristic evaluation apparatus comprised using the sample stand of this invention It shows the length dependence of the resistance of the _Bi 2 _Te 2.85 _{Se 0.15} blocks according to Example 4 Shows a cross-sectional area dependence of the electrical conductivity of the _Bi 2 _Te 2.85 _{Se 0.15} blocks according to Example 4 FIG. 5 shows an IV curve of a Bi ₂ Te ₃ nanowire array according to Example 5. It shows the IV curve of _Bi 2 Te ₃ nanowire array according to Comparative Example 6 The figure which shows the mode of the electric current which flows through the sample by Example 5 and Comparative Example 6 Diagram showing a relationship between the absolute Seebeck coefficient and temperature of the Bi ₂ Te ₃ nanowire array according to Example 7 Diagram showing the temperature dependence of the open-circuit voltage of the Bi ₂ Te ₃ nanowire array according to Example 7 and Comparative Example 8 The figure which shows the IV curve and output curve in each temperature difference of Ni plate by Example 9 Schematic diagram of a conventional thermoelectric property evaluation device

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In addition, the same number is attached | subjected to the same element and the description is abbreviate | omitted.

(Embodiment 1)
In Embodiment 1, a sample stage of the present invention will be described.
FIG. 1 is a schematic diagram of a sample stage of the present invention.
FIG. 2 is a schematic diagram of the thermocouple of the present invention.

  The sample stage 100 of the present invention is used for holding the sample 110 and evaluating the thermoelectric characteristics of the sample 110. The sample stage 100 includes a first block 130a in which a first thermocouple 120a that is insulated except for the tip is embedded, and a second block 130b in which a second thermocouple 120b that is insulated except for the tip is embedded. Is provided.

  The first thermocouple 120 a and the second thermocouple 120 b are coated with an insulating material 220 except for the tip 210. The insulating material 220 is an insulating material selected from the group consisting of polyethylene, polyvinyl chloride, natural rubber, polyester, epoxy resin, melamine resin, phenol resin, polyurethane resin, polyimide resin, and silicone synthetic resin, for example.

  As schematically shown in FIG. 1, in the sample stage 100 of the present invention, the tips (the tips are not insulated) of the first thermocouple 120a and the second thermocouple 120b are in contact with the sample 110. Thus, the sample 110 is sandwiched between the first block 130a and the second block 130b.

  Further, as shown in FIG. 2, the space between the first thermocouple 120a and the first block 130a other than the region where the first thermocouple 120a and the sample 110 are in contact, and the second thermocouple 120b. The space between the second thermocouple 120b and the second block 130b other than the region where the sample 110 and the sample 110 are in contact with each other is filled with a conductive material 140.

  With such a configuration, the gap between the first thermocouple 120a / second thermocouple 120b and the first block 130a / second block 130b can be eliminated and integrated, and in the measurement, the first thermocouple 120a / second thermocouple 120b can be integrated. It is only necessary that the thermocouple 120a / second thermocouple 120b be in contact with the sample 110. As a result, the sample 110 having an arbitrary thickness and cross-sectional area can be measured without considering the size of the first block 130a / second block 130b.

  Further, with such a configuration, the first electrode 14 of the thermoelectric characteristic evaluation apparatus 1 according to the conventional technique described with reference to FIG. 34 can be omitted, so that the resistance of the electrode or the resistance between the electrode and the sample is simplified. The thermoelectric characteristics can be measured with high accuracy.

  More preferably, the material 140 satisfies the absolute value of the absolute Seebeck coefficient at room temperature of 0 μV / K or more and 20 μV / K or less. Within this range, when measuring an excellent thermoelectric material having a Seebeck coefficient of 200 μV / K or more, a temperature difference equivalent to that of the sample is generated on the sample stage, and even if the measurement error is measured, the measurement error is 10%. The following can be suppressed. If the absolute value of the absolute Seebeck coefficient of the material 140 exceeds 20 μV / K, a temperature difference greater than that of the sample occurs on the sample stage, and high-precision measurement cannot be performed when the Seebeck coefficient of the sample stage is measured as an error during measurement. there is a possibility. As a condition for measuring the Seebeck coefficient of the sample stage as an error in measurement, there is a case where the thermocouple is short-circuited inside the sample stage. In addition, the room temperature in this specification is a temperature range of 20 ° C. or more and 25 ° C. or less.

  More preferably, the material 140 satisfies the absolute value of the absolute Seebeck coefficient at room temperature of 0 μV / K or more and 3 μV / K or less. Within this range, a temperature difference equivalent to that of the sample occurs on the sample stage, and the measurement error due to the sample stage can be suppressed to 1.5% or less even if the measurement error is measured.

  Such a material 140 includes Au, Al, Ag, Co, Cr, Cu, Fe, In, Ir, Mg, Mo, Ni, Pd, Pt, Ru, Su, Ti, W, Zn, and at least these It is selected from the group consisting of alloys containing either. All of these materials are preferable because they have the absolute value of the predetermined absolute Seebeck coefficient described above. Among them, the material 140 is preferably a paste made of Au because of easy handling. Examples of the alloy include nichrome, platinum rhodium alloy, and stainless steel. These satisfy the absolute value of the absolute Seebeck coefficient.

  Alternatively, such material 140 is from the group consisting of Au, Al, Ag, Co, Cr, Cu, Fe, In, Ir, Mg, Mo, Ni, Pd, Pt, Ru, Su, Ti, W and Zn. It may be an intermetallic compound containing at least one selected metal.

  The first thermocouple 120a exits from the planar end of the first block 130a and is connected to a voltmeter (indicated as “V” in FIG. 1). Similarly, the second thermocouple 120b exits from the planar end of the second block 130b and is connected to a voltmeter. With such a configuration, the sample 110 can be uniformly pressurized from above and below. As a result, for example, a change in contact resistance between the first block 130a / second two block 130b and the sample 110 for each setting of the sample 110 is reduced, and the thermoelectric characteristics can be evaluated with high accuracy.

  The first block 130a and the second block 130b have conductivity and are made of a material that allows heat to pass. Preferably, the first block 130a and the second block 130b are made of a heat conductive material having a heat conductivity at room temperature of 65 W / (m · K) or more. If the thermal conductivity satisfies this value, for example, even when the temperature gradient described later is formed on the sample stage of the present invention, not only the temperature gradient can be efficiently formed, but also highly accurate measurement can be achieved. . The upper limit is not particularly limited.

  More preferably, the first block 130a and the second block 130b are Au, Al, Ag, Co, Cr, Cu, Fe, In, Ir, Mg, Mo, Ni, Pd, Pt, Ru, Su, Ti. , W, Zn, and an alloy containing at least any one of them. All of these materials satisfy the above-described thermal conductivity and are easily available. Among these, the first block 130a and the second block 130b are preferably made of Cu from the viewpoint of simplicity of processing and handling. As described above, examples of the alloy include nichrome, platinum rhodium alloy, and stainless steel. These satisfy the thermal conductivity. For reference, Table 1 shows a list of thermal conductivity of these materials.

  Alternatively, the first block 130a and the second block 130b are more preferably Au, Al, Ag, Co, Cr, Cu, Fe, In, Ir, Mg, Mo, Ni, Pd, Pt, Ru, Su. , Ti, W and Zn may be used to form an intermetallic compound containing a metal selected from at least one selected from the group consisting of Ti, W and Zn.

  The sample stage 100 of the present invention is configured to sandwich the sample 110 between the first block 130a and the second block 130b, but at least the region of the sample 110 where the sample 110 and the first thermocouple 120a are in contact with each other. In addition, the electrode 150b is applied to at least the region of the sample 110 where the sample 110 and the second thermocouple 120b are in contact with each other. Thereby, the 1st thermocouple 120a and the 2nd thermocouple 120b contact the electrodes 150a and 150b, respectively.

  The electrodes 150a and 150b are preferably deposited by physical vapor deposition or chemical vapor deposition. Thereby, the contact resistance between the electrode 150a / 150b and the sample 110 and the contact resistance between the electrode 150a / 150b and the first block 130a / second block 130b can be reduced. More preferably, the thickness of the electrode is 400 nm or more. As a result, the electric conductivity of the electrodes 150a / 150b is stabilized, so that highly accurate measurement is possible. More preferably, the electrodes 150a and 150b may be coated with a metal paste in addition to the applied metal. Thereby, the contact resistance between the electrode 150a / 150b and the sample 110 and the contact resistance between the electrode 150a / 150b and the first block 130a / second block 130b can be further reduced.

  The materials of such electrodes 150a / 150b are Au, Al, Ag, Co, Cr, Cu, Fe, In, Ir, Mg, Mo, Ni, Pd, Pt, Ru, Su, Ti, W, Zn, and , At least one of these is selected from the group consisting of alloys. All of these materials satisfy the above-described thermal conductivity and are easily available. As described above, examples of the alloy include nichrome, platinum rhodium alloy, and stainless steel.

  Such a sample stage 100 may be accommodated in an external heater or a container provided with an external heater. As a result, the measurement temperature of the sample to be measured is made constant and the heat loss is minimized, so that the thermoelectric characteristics can be evaluated with high accuracy.

  Such a sample stage 100 can be replaced with gas, and may be housed in a container (chamber) capable of controlling the gas pressure. As a result, the measurement can be performed in the atmosphere, oxygen, vacuum, inert gas atmosphere or wet gas atmosphere described later. For example, when the sample 110 is chemically unstable in the atmosphere, it is preferable to use an inert gas as a predetermined gas under reduced pressure because the heat flow is stabilized and the sample can be measured in a chemically stable state. In order to stabilize the heat flow, measurement in a reduced pressure range of 0.01 MPa to 0.1 MPa is preferable.

  Of course, both the external heater and the gas pressure control may be used simultaneously, and the sample stage 110 may be provided with an external heater and housed in a gas replaceable container.

  The first thermocouple 120a and the second thermocouple 120b may be made of different materials, but are preferably made of the same material in order to simplify the calculation described later. For the same reason, the first block 130a and the second block 130b are also preferably made of the same material, and the electrodes 150a / 150b are also preferably made of the same material. In the following, for the sake of simplicity, the description will be made assuming that each is composed of the same material.

(Embodiment 2)
In the second embodiment, a thermoelectric property evaluation apparatus using the sample stage described in the first embodiment and a method for evaluating the thermoelectric property of a sample using the same will be described.

FIG. 3 is a schematic diagram of the thermoelectric property evaluation apparatus of the present invention.
FIG. 4 is a schematic diagram of a switch connected to the thermoelectric property evaluation apparatus of the present invention.

  The thermoelectric property evaluation apparatus 300 of the present invention includes a sample stage 100 that holds a sample 110, temperature gradient means 310a and 310b that form a temperature gradient in the sample 110, and a voltmeter 320 that measures a potential difference between the samples 110. . Since the sample stage 100 is the same as the sample stage 100 described in the first embodiment, the description thereof is omitted. The voltmeter 320 includes a first thermocouple 120a that exits from the end in the planar direction of the first block 130a of the sample stage 100 and a first thermocouple 120a that exits from the end in the planar direction of the second block 130b. 2 thermocouples 120b. Since the temperature difference and potential difference of the sample 110 can be measured by using the thermoelectric property evaluation apparatus 300 of the present invention, the Seebeck coefficient, the thermoelectromotive force, and the open circuit voltage of the sample 110 can be measured.

  The temperature gradient means 310a, 310b preferably includes a heating device and a cooling device. The temperature gradient means 310a is a heating device provided on the side of the first block 130a that faces the sample 110, and the temperature gradient means 310b faces the side of the second block 130b that contacts the sample 110. It is the cooling device provided in the side. Alternatively, the combination of the heating device and the cooling device may be reversed. A temperature gradient is formed between the samples 110 by such a combination of the heating device and the cooling device. Specifically, the heating device is an electric heater by resistance heating, a Peltier heater, or the like. Specifically, the cooling device is air cooling, water cooling, Peltier heater or the like. An exemplary combination of heating and cooling devices includes a Peltier heater / cooler.

  As shown in FIG. 4, the thermoelectric property evaluation apparatus 300 of the present invention further includes a switch 410 that opens and closes a voltage measurement circuit including a sample 110 and a voltmeter 320. Specifically, the switch 410 includes a zero contact 420 that holds the first thermocouple 120 a and the second thermocouple 120 b at 0 ° C., and a selector switch 430. This is preferable because errors due to the atmosphere and errors due to individual differences of measuring instruments can be eliminated.

  The thermoelectric property evaluation apparatus 300 of the present invention may be housed in an external heater. Thereby, the measurement temperature of the sample to be measured can be made constant, and the thermoelectric characteristics can be evaluated with higher accuracy. Alternatively, the thermoelectric property evaluation apparatus 300 of the present invention may be housed in a container (chamber) that can replace the gas and control the gas pressure, and measure in a predetermined atmosphere. The predetermined atmosphere is any of air, oxygen, vacuum, inert gas atmosphere, or wet gas atmosphere. For example, when the sample 110 is chemically unstable in the atmosphere, it is preferable to use an inert gas as a predetermined gas under reduced pressure because the heat flow is stabilized and the sample can be measured in a chemically stable state. In order to stabilize the heat flow, measurement in a reduced pressure range of 0.01 MPa to 0.1 MPa is preferable.

  Of course, both the external heater and the gas pressure control may be used simultaneously, and the thermoelectric property evaluation apparatus 300 may include an external heater and be housed in a gas replaceable container.

  Next, the difference between the thermoelectric characteristic evaluation apparatus using the sample stage of the present invention and the thermoelectric characteristic evaluation apparatus according to the prior art will be described using an equivalent circuit.

  FIG. 5 is a diagram showing an equivalent circuit of the thermoelectric characteristic evaluation apparatus of the present invention and the conventional thermoelectric characteristic evaluation apparatus shown in FIG.

  5A shows an equivalent circuit connected to a power source in the thermoelectric characteristic evaluation apparatus of the present invention shown in FIG. 3, and FIG. 5B shows the conventional thermoelectric characteristic evaluation apparatus shown in FIG. An equivalent circuit is shown.

Comparing FIG. 5A and FIG. 5B, the equivalent circuit of FIG. 5A includes at least the resistance (R _{electrode 14} ) of the electrode 14 (FIG. 34) shown in FIG. And it turns out that there is no contact resistance (R _{electrode 14 / electrode 15} ) between the electrode 14 and the electrode 15 (FIG. 34). In other words, if the sample stage 100 of the present invention is used, an electrode corresponding to the electrode 14 in FIG. The thermoelectric characteristics can be measured with high accuracy.

Next, a method for evaluating an absolute Seebeck coefficient as a thermoelectric characteristic of a sample using a thermoelectric characteristic evaluation apparatus (FIG. 3) provided with the sample stage of the present invention will be described.
FIG. 6 is a flowchart for evaluating an absolute Seebeck coefficient as a thermoelectric characteristic of a sample using the sample stage of the present invention.

  Step S610: The sample 110 provided with an electrode is sandwiched between the first block 130a and the second block 130b, and a temperature gradient is formed on the sample 110. The temperature gradient is formed by the temperature gradient means 310a and 310b shown in FIG.

  Step S620: A potential difference and a temperature difference between the samples 110 generated by the temperature gradient formed in Step S610 are measured. Here, the temperature difference is measured by the first thermocouple 120a and the second thermocouple 120b shown in FIG. 3, and the potential difference is measured by the voltmeter 320 shown in FIG. The potential difference measured here is the thermoelectromotive force.

  Step S630: Steps S610 and S620 are repeated for different temperature gradients. Thereby, the change of the temperature difference between the samples 110 and the change of the potential difference can be obtained.

Step S640: The absolute Seebeck coefficient is calculated using the change in temperature difference and the change in potential difference obtained in step S630. The absolute Seebeck coefficient is calculated by the following equation.
S = ∇E / ∇T + S _thermocouple
Here, S (μV / K) is an absolute Seebeck coefficient, and ∇T (K) and ∇E (μV) are changes in temperature difference and potential difference between the samples 110 obtained in step S630. , S _thermocouple (μV / K) is an absolute Seebeck coefficient of the material constituting the first thermocouple 120a and the second thermocouple 120b. Note that ∇E / ∇T is the relative Seebeck coefficient of the sample 110.

Here, referring to FIG. 5 again, an equation for calculating the absolute Seebeck coefficient described above is derived. The potential difference E can be expressed by the following equation using the Seebeck coefficient and the temperature difference.
E = S _120a ΔT _120a-V + S _150a ΔT _120a-150a + S ₁₁₀ ΔT _150a-150b + S _150b ΔT _120b-150b + S _120b ΔT _120b-V
= S _120a ΔT _120a-V + S ₁₁₀ ΔT _150a-150b + S _120b ΔT _120b-V
= S _120a ΔT _150a-150b + S ₁₁₀ ΔT _150a-150b
S _120a : Seebeck coefficient of the material constituting the first thermocouple 120a S _120b : Seebeck coefficient of the material constituting the second thermocouple _120b and satisfying S _120a = S _120b S _150a : constituting the electrode 150a Seebeck coefficient of material S _150b : Seebeck coefficient of material constituting electrode 150b, and satisfying S _150a = S _150b S ₁₁₀ : Seebeck coefficient of material constituting sample 110 ΔT _120a-V : First thermocouple 120a Temperature difference between the voltmeter ΔT _120b-V : Temperature difference between the second thermocouple 120b and the voltmeter ΔT _120a-V + ΔT _120b-V = ΔT _150a-150b
ΔT _120a-150a : temperature difference between the first thermocouple 120a and the electrode 150a (it is 0 because there is no temperature difference between the first thermocouple 120a and the electrode 150a)
ΔT _120b-150b : temperature difference between the second thermocouple 120b and the electrode 150b (there is no temperature difference between the second thermocouple 120b and the electrode 150b, which is 0)
ΔT _150a-150b : temperature difference between electrode 150a and electrode 150b (same as temperature difference of sample 110)

The relative Seebeck coefficient S ′ ₁₁₀ of the sample 110 is S ′ ₁₁₀ = ∇E / ∇T (∇E is a change in potential difference between the samples 110, and ∇T is a change in temperature difference between the samples 110). Because there is, the above formula becomes as follows.
S ₁₁₀ = S ′ ₁₁₀ + S _120a = ∇E / ∇T + S _thermocouple
As described above, when the sample stage 100 of the present invention is used, the absolute Seebeck coefficient of the sample 110 can be easily and highly accurately obtained only by obtaining changes in the temperature difference and potential difference between the samples 110.

  Note that step S610 and step S620 may be performed in the air, oxygen, vacuum, inert gas atmosphere or wet gas atmosphere. This is preferable because the sample can be measured for atmospheric stability, oxygen partial pressure dependency, and humidity dependency. For example, when the sample 110 is chemically unstable in the atmosphere, it is preferable to use an inert gas as a predetermined gas under reduced pressure because the heat flow is stabilized and the sample can be measured in a chemically stable state. In order to stabilize the heat flow, measurement in a reduced pressure range of 0.01 MPa to 0.1 MPa is preferable.

  Next, a method for evaluating an open circuit voltage as a thermoelectric characteristic of a sample using a thermoelectric characteristic evaluation apparatus (FIG. 3) provided with the sample stage of the present invention will be described.

  FIG. 7 is a flowchart for evaluating an open circuit voltage as a thermoelectric characteristic of a sample using the sample stage of the present invention.

  Step S710: Steps S610 to S640 in FIG. 6 are repeated at least two times for different temperatures. Steps S610 to S640 are the same as described above, and a description thereof will be omitted.

  Step S720: The absolute Seebeck coefficient obtained in step S710 is plotted against the temperature and fitted. For the fitting, a central processing unit storing software such as Kaleida Graph may be used.

  Step S730: The fitting equation obtained in step S720 is definitely integrated over the measured temperature range to calculate an open circuit voltage.

The inventors of the present application calculated the open circuit voltage calculated in this way as a dimensionless figure of merit ZT (= S ² σT / k; S is the Seebeck coefficient, and σ is the conductivity. And T is an absolute temperature and k is a thermal conductivity), and it was found that the accuracy is better than the approximate evaluation assuming that there is no temperature dependence of thermoelectric characteristics.

  Although not shown, the measured temperature difference, potential difference and the like may be stored in a memory, and the absolute Seebeck coefficient and the open circuit voltage may be calculated in the central processing unit.

(Embodiment 3)
In the third embodiment, another thermoelectric characteristic evaluation apparatus using the sample stage described in the first embodiment and a method for evaluating the thermoelectric characteristic of a sample using the same will be described.

  FIG. 8 is a schematic diagram of the thermoelectric property evaluation apparatus of the present invention.

  The thermoelectric property evaluation apparatus 800 of the present invention includes a sample stage 100 that holds a sample 110, a voltmeter 320 that measures a potential difference between the samples 110, and a power source 810 that applies a current to the sample 110. Since the sample stage 100 is the same as the sample stage 100 described in the first embodiment, the description thereof is omitted.

  The voltmeter 320 includes a first thermocouple 120a that exits from the end in the planar direction of the first block 130a of the sample stage 100 and a first thermocouple 120a that exits from the end in the planar direction of the second block 130b. 2 thermocouples 120b.

  The power source 810 is connected via current terminals 820a and 820b made of conductive wires wound around the first block 130a and the second block 130b of the sample stage 100, respectively. With this configuration, the entire apparatus can be reduced in size. Exemplary conductors are Au, Al, Ag, Co, Cr, Cu, Fe, In, Ir, Mg, Mo, Ni, Pd, Pt, Ru, Su, Ti, W, Zn, and at least any of these It is selected from the group consisting of alloys containing All of these materials are preferable because they have the absolute value of the predetermined absolute Seebeck coefficient described above. Examples of the alloy include nichrome, platinum rhodium alloy, and stainless steel.

  In the thermoelectric characteristic evaluation apparatus 800 of the present invention, since the power source 810 is not directly connected to the first thermocouple 120a and the second thermocouple 120b, it is possible to flow a current uniformly over the entire sample 110. Compared with a two-terminal thermoelectric characteristic evaluation apparatus, thermoelectric characteristics can be evaluated with high accuracy.

  FIG. 9 is a schematic diagram of another thermoelectric property evaluation apparatus of the present invention.

  Another thermoelectric property evaluation apparatus 900 of the present invention is the same except that the connection state of the power supply 810 that applies current to the sample 110 is different from that of the thermoelectric characteristic evaluation apparatus 800 of FIG. Specifically, the power source 810 includes current terminals 910a installed on the side facing the sample 110 of the first block 130a and the side facing the sample 110 of the second block 130b, respectively. Connected via 910b.

  Preferably, the current terminals 910a and 910b are composed of blocks 920a and 920b around which conductive wires are wound. With such a configuration, since the power source 810 can be retrofitted, the assembly of the apparatus is easy. The blocks 920a and 920b are preferably made of a heat conductive material having a thermal conductivity of 65 W / (m · K) or more at room temperature. Thereby, since heat resistance can be suppressed and heat can be efficiently transmitted to the sample, thermoelectric characteristics can be measured with high accuracy. The upper limit is not particularly limited. The blocks 920a and 920b can be made of the same material as the first block 130a and the second block 130b, for example.

  In the thermoelectric property evaluation apparatus 900 of the present invention, as with the thermoelectric characteristic evaluation device 800, the power source 810 is not directly connected to the first thermocouple 120a and the second thermocouple 120b, so that the current is uniformly supplied to the entire sample 110. Therefore, the thermoelectric characteristics can be evaluated with higher accuracy than the conventional two-terminal thermoelectric characteristic evaluation apparatus.

  Similarly to the thermoelectric characteristic evaluation apparatus 300, the thermoelectric characteristic evaluation apparatuses 800 and 900 of the present invention may be accommodated in an external heater. Thereby, the measurement temperature of the sample to be measured can be made constant, and the thermoelectric characteristics can be evaluated with higher accuracy. Alternatively, the thermoelectric property evaluation apparatuses 800 and 900 of the present invention may be gas-replaced and housed in a container whose gas pressure can be controlled, and measurement may be performed in a predetermined atmosphere. The predetermined atmosphere is any of air, oxygen, vacuum, inert gas atmosphere, or wet gas atmosphere. For example, when the sample 110 is chemically unstable in the atmosphere, it is preferable to use an inert gas as a predetermined gas under reduced pressure because the heat flow is stabilized and the sample can be measured in a chemically stable state. In order to stabilize the heat flow, measurement in a reduced pressure range of 0.01 MPa to 0.1 MPa is preferable.

  By using such thermoelectric property evaluation apparatuses 800 and 900 of the present invention, the potential difference when a predetermined current is applied to the sample 110 can be measured, so that the internal resistance and electrical conductivity of the sample 110 can be calculated.

Next, a method for evaluating internal resistance and electrical conductivity as thermoelectric characteristics of a sample using a thermoelectric characteristic evaluation apparatus (FIGS. 8 and 9) provided with the sample stage of the present invention will be described.
FIG. 10 is a flowchart for evaluating internal resistance and electrical conductivity as thermoelectric characteristics of a sample using the sample stage of the present invention.

  Step S1010: The sample 110 provided with an electrode is sandwiched between the first block 130a and the second block 130b, and a current is applied to the sample 110. The application of current is performed by a power source 810 shown in FIGS.

  Step S1020: The potential difference between the samples 110 to which current is applied is measured. The potential difference is measured by a voltmeter 320 shown in FIGS.

  Step S1030: Steps S1010 and S1020 are repeated. At this time, a current having a magnitude different from that in step S1010 is applied.

Step S1040: The internal resistance of the sample 110 is calculated from the change in current value and the change in potential difference obtained in step S1030. The internal resistance is calculated according to the following formula.
R = ∇V / ∇I
Here, R is the internal resistance of the sample 110, ∇I (A) is the change in the current value obtained in step S101030, and ∇V is the distance between the measured samples 110 obtained in step S1030. This is a change in the potential difference.

  As described above, when the sample stage 100 of the present invention is used, a current is applied to the sample 110, and the potential difference at that time is easily measured. Therefore, the internal resistance of the sample 110 can be obtained easily and with high accuracy. Note that step S1010 and step S1020 may be performed in the air, oxygen, vacuum, inert gas atmosphere, or wet gas atmosphere. This is preferable because the sample can be measured for atmospheric stability, oxygen partial pressure dependency, and humidity dependency. Specifically, for example, when the sample 110 is chemically unstable in the atmosphere, the heat flow can be stabilized and the sample can be measured in a chemically stable state by using an inert gas as a predetermined gas under reduced pressure. This is preferable because it is possible. In order to stabilize the heat flow, measurement in a reduced pressure range of 0.01 MPa to 0.1 MPa is preferable.

Step S1050: The electrical conductivity of the sample 110 is calculated using the internal resistance of the sample 110 obtained in step S1040. Calculation of electric conductivity is calculated | required by following Formula.
σ = L / {(RR _{contact resistance} ) A}
Here, σ (S / cm) is the electrical conductivity of the sample 110, L (cm) is the length of the sample 110, A (cm ² ) is the cross-sectional area of the sample 110, and R (Ω) is the internal resistance of the sample 110 obtained in step S1040, R _{contact resistance} (Ω) is the resistance value between the sample 110 and the electrodes 150a and 150b, and the resistance of the material constituting the electrodes 150a and 150b. Value, the resistance value between the electrode 150a and the first thermocouple 120a, the resistance value between the electrode 150b and the second thermocouple 120b, and the first thermocouple 120a and the second thermocouple 120b. This is the total resistance value of the constituent materials.

When the sample stage 100 of the present invention is used, if the R _{contact resistance} is known, L and A are fixed values, so that the electrical conductivity can be easily obtained. The R _{contact resistance} corresponds to the resistance value when the sample length is zero when the change of the resistance value with respect to the length of the sample 110 (the cross-sectional area of the sample is constant) is plotted. Such a method for calculating the R _{contact resistance} will be described using a thermoelectric property evaluation apparatus (FIGS. 8 and 9) provided with the sample stage of the present invention.

  FIG. 11 is a flowchart for calculating the contact resistance using the sample stage of the present invention.

  Step S1110: The sample 110 provided with an electrode is sandwiched between the first block 130a and the second block 130b, and current is applied to the sample 110. The application of current is performed by a power source 810 shown in FIGS. Here, the sample 110 has a constant cross-sectional area and various lengths. This operation is the same as step S1010 in FIG.

  Step S1120: The potential difference between the samples 110 to which current is applied is measured. The potential difference is measured by a voltmeter 320 shown in FIGS. At this time, the potential difference is measured for various lengths of the sample 110. This operation is the same as step S1020 in FIG.

  Step S1130: Steps S1110 and S1120 are repeated. At this time, a current having a magnitude different from that in step S1110 is applied.

Step S1140: The resistance (internal resistance) of the sample 110 is calculated from the change in current value and the change in potential difference obtained in step S1130. The resistance is calculated according to the following equation.
R = ∇V / ∇I
Here, R is the resistance of the sample 110, ∇I (A) is a change in the current value obtained in step S1130, and ∇V is a change in the potential difference obtained in step S1130. This operation is the same as step S1040 in FIG.

  Step S1150: The resistance (corresponding to the internal resistance) is calculated from the potential difference with respect to the sample 110 of various lengths obtained in steps S1110 to S1140, and the resistance value (resistance value) is plotted against the length of the sample 110. . The resistance value when the length of the sample 110 is 0 is read.

  The read value is the resistance value between the sample 110 and the electrodes 150a and 150b, the resistance value of the material constituting the electrodes 150a and 150b, the resistance value between the electrode 150a and the first thermocouple 120a, and the electrode 150b. And the second thermocouple 120b, and the contact resistance which is the sum of the resistance values of the materials constituting the first thermocouple 120a and the second thermocouple 120b.

If the value read here is applied to the R _{contact resistance} in step S1050 in FIG. 10, even when each resistance value is unknown, the electric conductivity can be easily and accurately obtained.

  In addition, the calculation of the contact resistance in FIG. 11 is effective for the evaluation of the electrode used in the case where the sample is a known thermoelectric material. Steps S1110 to S1150 may be performed as in FIG.

Step S1110: A sample made of a thermoelectric material provided with an electrode is sandwiched between the first block 130a and the second block 130b, and current is applied to the sample. The application of current is performed by a power source 810 shown in FIGS. Here, the sample made of the thermoelectric material has a constant cross-sectional area and various lengths.
Step S1120: Measuring a potential difference between samples to which a current is applied. The potential difference is measured by a voltmeter 320 shown in FIGS. At this time, the potential difference is measured for various lengths of the sample.
Step S1130: Steps S1110 and S1120 are repeated.
Step S1140: The resistance (internal resistance) of the sample 110 is calculated from the current value and the potential difference.
Step S1150: Based on steps S1110 to S1140, resistance values are plotted for samples of various lengths, and the resistance values when the sample length is 0 are read.

  Since the resistance value obtained in this way is a contact resistance, the electrode used for the thermoelectric material can be evaluated by comparing and examining the contact resistance when various electrodes are used. For example, when the contact resistance is small, it can be evaluated that the thermoelectric material and the electrode used therefor are suitable for the thermoelectric material. When the contact resistance is large, the thermoelectric material and the electrode used therefor are the thermoelectric material concerned. It can be evaluated that it is unsuitable for. Such a contact resistance criterion is illustratively suitable as an electrode if the contact resistance is 1/100 or less than the resistance of the thermoelectric material, and unsuitable as an electrode if the contact resistance exceeds the resistance of the thermoelectric material. .

(Embodiment 4)
In the fourth embodiment, another thermoelectric property evaluation apparatus using the sample stage described in the first embodiment and a method for evaluating the thermoelectric property of a sample using the same will be described.

  FIG. 12 is a schematic diagram of the thermoelectric property evaluation apparatus of the present invention.

  The thermoelectric property evaluation apparatus 1200 of the present invention includes a power source 810 that applies a current to the sample 110 in addition to the thermoelectric characteristic evaluation device 300 described with reference to FIG. The power source 810 is connected via current terminals 820a and 820b made of conductive wires wound around the first block 130a and the second block 130b of the sample stage 100, respectively. Exemplary conductors are Au, Al, Ag, Co, Cr, Cu, Fe, In, Ir, Mg, Mo, Ni, Pd, Pt, Ru, Su, Ti, W, Zn, and at least any of these It is selected from the group consisting of alloys containing Examples of the alloy include nichrome, platinum rhodium alloy, and stainless steel. These materials are preferable because they have high thermal conductivity. Other elements are the same as those described with reference to FIG.

  In addition, it can be said that the thermoelectric property evaluation apparatus 1200 of the present invention includes temperature gradient means 310 a and 310 b that form a temperature gradient on the sample 110 in addition to the thermoelectric characteristic evaluation device 800 described with reference to FIG. 8.

  FIG. 13 is a schematic diagram of another thermoelectric property evaluation apparatus of the present invention.

  Another thermoelectric characteristic evaluation apparatus 1300 of the present invention is the same as the thermoelectric characteristic evaluation apparatus 1200 of the present invention in that it includes a power source 810 that applies a current to the sample 110 in addition to the thermoelectric characteristic evaluation apparatus 300 described in FIG. However, the power source 810 is connected via current terminals 910a and 910b installed between the first block 130a and the heating device 310a, and between the second block 130b and the cooling device 310b, respectively. The They are connected via current terminals 820a and 820b made of conductive wires wound around the first block 130a and the second block 130b of the sample stage 100, respectively. Preferably, the current terminals 910a and 910b are composed of blocks 920a and 920b around which conductive wires are wound. These blocks 920a and 920b are preferably made of a thermoelectric material having a thermal conductivity of 65 W / (m · K) or more at room temperature. Thereby, since heat resistance can be suppressed and heat can be efficiently transmitted to the sample, thermoelectric characteristics can be measured with high accuracy. The upper limit is not particularly limited. Other elements are the same as those described with reference to FIG.

  It can be said that another thermoelectric property evaluation apparatus 1300 of the present invention includes temperature gradient means 310a and 310b that form a temperature gradient in the sample 110 in addition to the thermoelectric characteristic evaluation device 900 described with reference to FIG.

  Similarly to the thermoelectric characteristic evaluation apparatuses 300, 800, and 900, the thermoelectric characteristic evaluation apparatuses 1200 and 1300 of the present invention may be accommodated in an external heater. Thereby, the measurement temperature of the sample to be measured can be made constant, and the thermoelectric characteristics can be evaluated with higher accuracy. Alternatively, the thermoelectric property evaluation apparatuses 1200 and 1300 of the present invention may be gas-replaced and housed in a container whose gas pressure can be controlled, and measurement may be performed in a predetermined atmosphere. The predetermined atmosphere is any of air, oxygen, vacuum, inert gas atmosphere, or wet gas atmosphere. For example, when the sample 110 is chemically unstable in the atmosphere, it is preferable to use an inert gas as a predetermined gas under reduced pressure because the heat flow is stabilized and the sample can be measured in a chemically stable state. In order to stabilize the heat flow, measurement in a reduced pressure range of 0.01 MPa to 0.1 MPa is preferable.

  If the thermoelectric characteristic evaluation apparatuses 1200 and 1300 of the present invention are used, the thermoelectric characteristic evaluation apparatus 300 and the thermoelectric characteristic evaluation apparatuses 800 and 900 have both functions. In addition to the evaluation of circuit voltage, internal resistance, and electrical conductivity, the effective maximum output and maximum output density of sample 110 can be calculated. The effective maximum output is an index for comparing the maximum power obtained when a temperature difference is given to a certain sample, and is a value in which the sample size is wattage per meter unit. The maximum output density is an index for evaluating the output of a module including an element made of one or more thermoelectric materials, for example. By evaluating such an effective maximum output and maximum output density, the sample and the module can be evaluated using the output (W) which is the same index.

Next, a method for evaluating an effective maximum output as a thermoelectric characteristic of a sample using a thermoelectric characteristic evaluation apparatus (FIGS. 12 and 13) provided with the sample stage of the present invention will be described.
FIG. 14 is a flowchart for evaluating an effective maximum output as a thermoelectric characteristic of a sample using the sample stage of the present invention.

  Step S1010: The sample 110 provided with an electrode is sandwiched between the first block 130a and the second block 130b, and a current is applied to the sample 110. The application of current is performed by a power source 810 shown in FIGS.

  Step S1020: The potential difference between the samples 110 to which current is applied is measured. The potential difference is measured by a voltmeter 320 shown in FIGS.

  Step S1030: Steps S1010 and S1020 are repeated.

Step S1040: The internal resistance of the sample 110 is calculated from the change in current value and the change in potential difference obtained in step S1030. The internal resistance is calculated according to the following formula.
R = ∇V / ∇I
Here, R is the internal resistance of the sample 110, ∇I (A) is the change in the current value obtained in step S1030, and ∇V is the change in the potential difference obtained in step S1030.

  Step S1410: A temperature gradient is formed on the sample. The temperature gradient is formed by the temperature gradient means 310a and 310b shown in FIGS.

  Step S1420: The potential difference between the samples 110 generated by the temperature gradient formed in step S1410 is measured. The potential difference is measured by a voltmeter 320 shown in FIGS.

Step S1430: The effective maximum output of the sample 110 is calculated using the internal resistance obtained in Step S1040 and the potential difference obtained in Step S1420. The effective maximum output is calculated by the following equation.
P _max = {(ΔE) ² × L} / {4 × R × A}
Here, P _max is the effective maximum output of the sample 110, ΔE (μV) is the potential difference (corresponding to the open circuit voltage) measured in step S1420, and L (cm) is the length of the sample 110. R (Ω) is the internal resistance of the sample 110 obtained in step S1040, and A (cm ² ) is the cross-sectional area of the sample 110.

  As described above, when the sample stage 100 of the present invention is used, the effective maximum output of the sample 110 can be obtained easily and with high accuracy only by obtaining the internal resistance of the sample 110 and the potential difference when the temperature gradient is formed.

  Here, steps S1010 to S1040 are performed first, and then steps S1410 to 1430 are performed. However, steps S1410 to S1420 are performed first, then steps S1010 to S1040 are performed, and finally S1430 is performed. Also good.

  These steps S1010 to S1040 are the same as the internal resistance evaluation method described with reference to FIG. Here, it is assumed that the thermoelectric characteristic evaluation apparatuses 1200 and 1300 in FIGS. 12 and 13 are used. For example, the thermoelectric characteristic evaluation apparatuses 800 and 900 in FIGS. 8 and 9 are used, and steps S1010 to S1040 are performed. Steps S1410 to 1420 may be performed using the thermoelectric property evaluation apparatus 300 of FIG. 3, and step S1430 may be performed using the internal resistance and the potential difference obtained from these.

  Furthermore, the maximum output density of a module including an element made of one or more thermoelectric materials can be evaluated using the effective maximum output obtained in step S1430. Specifically, when the sample 110 described above is a module, the module includes one or more elements made of an n-type thermoelectric material and / or a p-type thermoelectric material. For example, in the temperature dependence of the Seebeck coefficient, the thermoelectric material can be determined to be n-type when the Seebeck coefficient has a negative slope and p-type when the Seebeck coefficient has a positive slope.

Following step S1430, the maximum output density of the sample 110, which is a module, is calculated based on the following equation.
P _A = {(P _{max (n)} + P _{max (p)} ) × a} / (2 × L)
Here, P _A is the maximum output density of the sample 110, P _{max (n)} is the effective maximum output of the n-type thermoelectric material, and P _{max (p)} is the effective maximum output of the p-type thermoelectric material. Yes, a (%) is the filling rate of the n-type thermoelectric material and / or p-type thermoelectric material in the module, and L (cm) is the length of the n-type thermoelectric material and / or p-type thermoelectric material .

For example, it is assumed that the sample 110 that is a module is composed of one n-type thermoelectric material and one p-type thermoelectric material. Here, the lengths of the n-type thermoelectric material and the p-type thermoelectric material are both L1 (cm), and the filling rate of the n-type thermoelectric material and the p-type thermoelectric material in the sample 110 is a1 (%). And When the effective maximum output of the n-type thermoelectric material and the p-type thermoelectric material is determined as P _{max1 (n)} and P _{max1 (p)} based on steps S1010 to S1040 and S1410 to S1430 in FIG. The maximum power density P _A of
P _A = {(P _{max1 (n)} + P _{max1 (p)} ) × a1} / (2 × L1)
It can be asked.

  As described above, when the sample stage 100 of the present invention is used, even if the sample 110 is a module, the maximum output density can be easily and accurately obtained only by obtaining the effective maximum output of the thermoelectric material constituting the module. it can.

  The present invention will now be described in detail using specific examples, but it should be noted that the present invention is not limited to these examples.

[Example 1]
In Example 1, the thermoelectromotive force and absolute Seebeck coefficient of a Si wafer (Si <100>) as a sample were evaluated using the sample stage of the present invention.

  With reference to FIG. 1, the sample stage of Example 1 will be described. In the sample stage of Example 1, the first block 130a and the second block 130b are made of Cu. The first block 130a and the second block 130b include a T-type (copper / constantan) first thermocouple 120a and a second thermoelectric, each of which is insulated with an insulating material 220 of a silicone synthetic resin except for the tip. The pair 120b is embedded. The diameters of the first thermocouple 120a and the second thermocouple 120b were 0.127 mm. The length of copper used was 20 m, and the length of constantan was 10 m. In order to perform accurate temperature measurement, an ice bath was used at the reference junction of the thermocouple.

  The space between the first thermocouple 120a and the first block 130a other than the area where the first thermocouple 120a and the sample are in contact, and the second area other than the area where the second thermocouple 120b and the sample are in contact with each other. The space between the thermocouple 120b and the second block 130b is filled with Au paste as a conductive material 140.

  The absolute Seebeck coefficient of Au at room temperature (300 K) was 1.94 μV / K. The absolute Seebeck coefficient of Cu at room temperature (300 K) was 1.84 μV / K. Further, the thermal conductivity of Cu at room temperature (300 K) was 401 W / (m · K).

  FIG. 15 is a diagram showing an external appearance (A) and a schematic diagram (B) of a thermoelectric property evaluation apparatus configured using the sample stage of the present invention.

  FIG. 15 is a sample table including a first block 130a made of Cu and a second block 130b made of Cu, in which a first thermocouple 120a and a second thermocouple 120b are embedded, respectively. A state of sandwiching the Si wafer is shown. Further, the thermoelectric characteristic evaluation apparatus shown in FIG. 15 is provided with Peltier heater / cooler (manufactured by Kelk) as temperature gradient means 310a and 310b for forming a temperature gradient in the sample 110, and the first thermocouple 120a and the first thermocouple A high-accuracy nanovoltmeter (model 2182, manufactured by Keithley Instrument) was provided as a voltmeter 320 for measuring the potential difference between the samples 110 via the two thermocouples 120b. Such a configuration is the same as that of the thermoelectric characteristic evaluation apparatus 300 described with reference to FIG.

  In the thermoelectric characteristic evaluation apparatus shown in FIG. 15, heat sinks 1510a and 1510b for releasing heat are provided in the temperature gradient means 310a and 310b, respectively. The thermoelectric characteristic evaluation apparatus shown in FIG. 15 is accommodated in an aluminum container provided with a flexible heater (made by TAIKA, FH3) as an external heater 1520.

  FIG. 16 shows an appearance (A) and a schematic diagram (B) of a gas replacement chamber containing the thermoelectric property evaluation apparatus shown in FIG.

  Box 1610 schematically shows the thermoelectric property evaluation apparatus shown in FIG. A thermoelectric property evaluation apparatus 1610 shown in FIG. 15 is housed in a gas replacement chamber 1620 so that the gas can be replaced. In Example 1, the measurement atmosphere was replaced with He gas, and then the pressure was reduced to 0.09 MPa.

  The thermoelectric power and absolute Seebeck coefficient of a Si wafer were measured as samples using the thermoelectric property evaluation apparatus provided with the sample stage of the present invention described above. The Si wafer had a size of 4 mm square and a thickness of 500 μm. An Au film was deposited on the Si wafer as an electrode by sputtering so as to have a thickness of 400 nm or more, and then an Au paste was applied.

Specifically, the sample was sandwiched between the first block and the second block in the thickness direction, and a temperature gradient was formed on the sample (step S610 in FIG. 6). The potential difference and temperature difference of the sample were measured (step S620 in FIG. 6). Next, a further different temperature gradient was formed, and the potential difference and temperature difference of the sample in the temperature gradient were measured (step S630). This was repeated, and the change in potential difference (∇E) and the change in temperature difference (∇T) were measured. The absolute Seebeck coefficient (S = ∇E / ∇T + S _thermocouple ) in the thickness direction of the sample was calculated using the obtained temperature difference and potential difference change (step S640 in FIG. 6). The results are shown in FIG.

  FIG. 17 shows a schematic diagram of a thermoelectric property evaluation apparatus for measuring the longitudinal direction according to the prior art.

  For comparison, the Seebeck coefficient was measured as the thermoelectric characteristic in the longitudinal direction of the Si wafer by using the thermoelectric characteristic evaluation apparatus for measuring the longitudinal direction according to the conventional technique shown in FIG. The results are shown in FIG.

[Example 2]
In Example 2, using the sample stage of the present invention, the absolute Seebeck coefficient of a Ni plate as a sample was evaluated. The Ni plate had a size of 4 mm square and a thickness of 300 μm. An Au film as an electrode was deposited on this Ni plate by sputtering so as to have a thickness of 400 nm or more.

  A temperature gradient was formed in the thickness direction of the Ni plate in the same manner as in Example 1, and the temperature difference and potential difference at that time were measured to obtain the absolute Seebeck coefficient. The results are shown in FIG.

  Here, for comparison, the temperature difference and the potential difference were measured as the thermoelectric characteristics in the longitudinal direction of the Ni plate using the thermoelectric characteristic evaluation apparatus for measuring the longitudinal direction according to the prior art shown in FIG. 17, and the absolute Seebeck coefficient was obtained. . The results are shown in FIG.

[Example 3]
In Example 3, using the sample stage of the present invention, the thermoelectromotive force of a Bi ₂ Te ₃ nanowire array was evaluated as a sample. Here, as described in FIG. 4, the first thermocouple 120 a and the second thermocouple 120 b of the thermoelectric characteristic evaluation apparatus of FIG. 16 are connected in the order of the zero contact 420, the selector switch 430, and the voltmeter 320.

Bi ₂ Te ₃ was vapor-deposited on a porous transparent anodic aluminum oxide filter to obtain a Bi ₂ Te ₃ nanowire array (0.04 cm ² , thickness 50 μm). Such a Bi ₂ Te ₃ nanowire array is shown in FIG. On the Bi ₂ Te ₃ nanowire array, an Au film was deposited as an electrode to a thickness of 400 nm or more by sputtering, and then an Au paste was applied.

A temperature gradient was formed in the thickness direction of the Bi ₂ Te ₃ nanowire array in the same manner as in Example 1, and the temperature difference and potential difference at that time were measured to determine the absolute Seebeck coefficient. The results are shown in FIGS.

  Details of the samples of Examples 1 to 3 and a list of measurement environments are shown in Table 2 for simplicity, and the results will be described.

  FIG. 18 is a graph showing the temperature difference dependency of the thermoelectromotive force of the Si wafer according to Example 1.

FIG. 18A shows the temperature difference dependency of the total thermoelectromotive force in the longitudinal direction of the Si wafer, and FIG. 18B shows the temperature difference dependency of the total thermoelectromotive force in the thickness direction of the Si wafer. . The absolute value of the total thermoelectromotive force increased linearly as the temperature difference increased. The approximate curve shown in FIG. 18B is given by y = −5.9169-186.38x (R = 0.99997). x is a temperature difference and y is a thermoelectromotive force. Here, the slope of the approximate curve is a relative Seebeck coefficient in the thickness direction of the Si wafer. That is, since the absolute Seebeck coefficient S = S _relative + S _{thermocouple (Cu)} , S = −186.38 + 1.84≈−185 μV / K. On the other hand, the absolute Seebeck coefficient in the longitudinal direction of the Si wafer was −179 μV / K, which coincided with that in the thickness direction of the Si wafer.

  FIG. 19 is a diagram showing the temperature dependence of the absolute Seebeck coefficient of the Ni plate according to Example 2.

  In FIG. 19, the temperature on the first block side is plotted on the horizontal axis, and the absolute Seebeck coefficient obtained at that temperature is plotted. 19, ● represents the absolute Seebeck coefficient calculated using the thermoelectric characteristic evaluation apparatus of FIG. 16, and ○ represents AT Burkov et al., Meas. Sci. Technol. , 2001, 12, 264, the absolute Seebeck coefficient of Ni bulk, and ■ is the absolute Seebeck coefficient calculated using the thermoelectric property evaluation apparatus for measuring the longitudinal direction according to the prior art of FIG. From these results, the absolute Seebeck coefficient value in the thickness direction of the Ni plate calculated using the thermoelectric property evaluation apparatus equipped with the sample stage of the present invention shown in FIG. Compared with the value of the absolute Seebeck coefficient in the longitudinal direction of the Ni plate measured by the characteristic evaluation apparatus, although it has a difference of 2 to 3 μV / K in absolute value, it was relatively close. Further, it was found that the absolute Seebeck coefficient in the thickness direction of the Ni plate was slightly not like the Ni bulk reported by AT Burkov et al.

  FIG. 18 and FIG. 19 show that the absolute Seebeck coefficient in the thickness direction can be calculated by performing the method of FIG. 6 using the thermoelectric characteristic evaluation apparatus having the sample stage of FIG. .

FIG. 20 is a diagram showing the appearance of the Bi ₂ Te ₃ nanowire array according to Example 3.

FIG. 20A shows the external appearance of the anodized aluminum oxide filter before the deposition of Bi ₂ Te ₃ . As shown in FIG. 20 (A), the anodized aluminum filter was a porous transparent filter. On the other hand, in FIG. 20B, the whole was black and opaque, and it was confirmed that Bi ₂ Te ₃ was deposited on the porous portion of the anodized aluminum filter.

FIG. 21 is a diagram illustrating the temperature at both ends of the Bi ₂ Te ₃ nanowire array according to Example 3 and the heater output dependence of the temperature difference.

  According to FIG. 21, with the increase in the output of the Peltier heater / cooler, the first block side became higher temperature and the second block side became lower temperature. Furthermore, the temperature difference between the samples increased linearly with respect to the heater output, and the temperature difference was controlled to 2K or less by the heater output.

FIG. 22 is a diagram showing the temperature difference dependence of the thermoelectromotive force of the Bi ₂ Te ₃ nanowire array according to Example 3.

According to FIG. 22, the absolute value of the thermoelectromotive force of the Bi ₂ Te ₃ nanowire array increased linearly with respect to the heater output. The approximate curve shown in FIG. 22 is given by y = −2.572−52.07x (R = 0.99991). x is a temperature difference and y is a thermoelectromotive force. Here, the slope of the approximate curve is a relative Seebeck coefficient in the thickness direction of the Bi ₂ Te ₃ nanowire array. That is, since the absolute Seebeck coefficient S = S _relative + S _{thermocouple (Cu)} , S = −52.07 + 1.84≈−50 μV / K.

FIG. 23 is a diagram showing the temperature dependence of the absolute Seebeck coefficient of the Bi ₂ Te ₃ nanowire array according to Example 3.

In FIG. 23, as described with reference to FIG. 22, the absolute Seebeck coefficient of the Bi ₂ Te ₃ nanowire array is plotted with respect to the measurement temperature using the relational expression of the absolute Seebeck coefficient S (● in FIG. 23). ). For reference, CV Manzano et al. Solid State Electrochem. , 2013, 17, 2071 together with the temperature dependence of the absolute Seebeck coefficient of the electrodeposited Bi ₂ Te ₃ film (■ in FIG. 23).

The absolute value of the absolute Seebeck coefficient of the Bi ₂ Te ₃ nanowire array tended to increase with increasing temperature. Specifically, the absolute Seebeck coefficient for Bi ₂ Te ₃ nanowire arrays decreased from −50 μV / K to −60 μV / K with increasing temperature from 297 K to 368 K. This indicates that the Bi ₂ Te ₃ nanowire array is n-type conductive, and the absolute Seebeck coefficient of the Bi ₂ Te ₃ nanowire array was close to that of the Bi ₂ Te ₃ film shown as the reported value.

Although not shown, Y.M. According to Ma et al., Electrochimica Acta, 2011, 56, 4216, the absolute Seebeck coefficient of Te-rich Bi ₂ Te ₃ thin film at room temperature is in the range of −51.6 μV / K to −58.3 μV / K. Has been. B. Deb et al., Mater. Trans. 2012, 53, 8, 1481, it is reported that a Bi-rich Bi ₂ Te ₃ electrodeposition film has p-type conduction.

From these, the Bi ₂ Te ₃ nanowire array used in Example 3 has a Te-rich composition. With such a composition, Te replaces the Bi site, and donors such as Te antisite defects are formed. It has been found that mold defects can be generated.

  From FIG. 18 to FIG. 23, by using the thermoelectric property evaluation apparatus having the sample stage of FIG. 1 and performing the method of FIG. 6, even if the thickness of the sample is a bulk size, It was shown that the thermoelectromotive force and the absolute Seebeck coefficient can be accurately calculated even when the film is thin.

[Example 4]
In Example 4, the contact resistance, internal resistance, and electrical conductivity of a Bi ₂ Te _2.85 Se _0.15 block (n-type conduction) were evaluated as samples using the sample stage of the present invention.

  When the contact resistance, internal resistance or electrical conductivity of a thermoelectric material is evaluated, the thickness of the electrode used for the thermoelectric material can affect. Therefore, prior to the evaluation of the thermoelectric characteristics described above, the influence of the electrode thickness on the electrical conductivity was investigated, and the electrode thickness was optimized.

  Au layers having various thicknesses were formed on a glass substrate. The thickness of the Au layer was 0 nm, 25 nm, 50 nm, 75 nm, 100 nm, 125 nm, 150 nm, 175 nm, 200 nm, 250 nm, 300 nm, 350 nm, 400 nm, 500 nm and 600 nm. The electrical conductivity of the Au layers of various thicknesses on the glass substrate was measured using a thermoelectric property evaluation apparatus for measuring the longitudinal direction according to the prior art shown in FIG. The results are shown in FIG.

  FIG. 24 is a diagram showing the film thickness dependence of the electrical conductivity of Au.

  According to FIG. 24, it was found that the electrical conductivity of Au increases as the film thickness increases, but becomes saturated and stable when the film thickness exceeds 400 nm. Therefore, in the subsequent measurement, the film thickness of the Au electrode applied to the sample was set to 400 nm or more.

  FIG. 25 is a diagram showing an external appearance (A) and a schematic diagram (B) of a thermoelectric property evaluation apparatus configured using the sample stage of the present invention.

Since the sample stage is the same as the sample stage described in the first embodiment, the description is omitted. FIG. 25 is a sample stage including a first block 130a made of Cu and a second block 130b made of Cu, in which a first thermocouple 120a and a second thermocouple 120b are embedded, respectively. A state in which a Bi ₂ Te _2.85 Se _0.15 block is sandwiched is shown.

  The thermoelectric characteristic evaluation apparatus shown in FIG. 25 includes a high-precision nanovoltmeter (manufactured by Keithley Instrument, as a voltmeter 320 for measuring a potential difference between the samples 110 via the first thermocouple 120a and the second thermocouple 120b. model 2182).

  Furthermore, the thermoelectric property evaluation apparatus shown in FIG. 25 is installed on the side facing the sample 110 of the first block 130a and the side facing the sample 110 of the second block 130b. A power source 810 connected via current terminals 910a and 910b is provided. The current terminals 910a and 910b were made of Cu blocks 920a and 920b around which Cu was wound. The power source 810 was a power meter (Keithley Instruments, model 2400). Such a configuration is the same as that of the thermoelectric property evaluation apparatus 900 described with reference to FIG.

  The thermoelectric property evaluation apparatus shown in FIG. 25 was accommodated in the gas replacement chamber shown in FIG. In Example 4, as in Example 1, the measurement atmosphere was replaced with He gas, and then the pressure was reduced to 0.09 MPa.

The contact resistance, internal resistance, and electrical conductivity of a Bi ₂ Te _2.85 Se _0.15 block as a sample were measured using the thermoelectric property evaluation apparatus equipped with the sample stage of the present invention described above. The Bi ₂ Te _2.85 Se _0.15 block had dimensions of 0.38 mm × 0.43 mm and various thicknesses (0.1 cm, 0.15 cm, 0.25 cm and 0.375 cm). On the Bi ₂ Te _2.85 Se _0.15 block, an Au film was deposited as an electrode to a thickness of 400 nm or more by sputtering, and then an Au paste was applied.

  Specifically, the sample was sandwiched between the first block and the second block in the thickness direction, and current was applied to the sample (step S1010 in FIG. 10 or step S1110 in FIG. 11). The potential difference of the sample was measured (step S1020 in FIG. 10 or step S1120 in FIG. 11). These were repeated (step S1030 in FIG. 10 or step S1130 in FIG. 11). These were performed on samples of each length, and the resistance was calculated from the current value and the potential difference (step S1040 in FIG. 10 or step S1140 in FIG. 11). The calculation of the resistance is R = ∇V / ∇I (where R (Ω) is the resistance of the sample (corresponding to the internal resistance), and ∇I (A) is the change in the current value applied to the sample. And ∇V (V) is the change in potential difference between samples). Next, the obtained resistance values were plotted against the sample length, and the resistance value (contact resistance) when the sample length was 0 was obtained (step S1150 in FIG. 11). The results are shown in FIG.

Next, electrical conductivity was calculated using the obtained contact resistance value (step S1050 in FIG. 10). The electrical conductivity is σ = L / {(RR _{contact resistance} ) A} (where σ (S / cm) is the electrical conductivity of the sample, and L (cm) is the length of the sample. A (cm ² ) is the cross-sectional area of the sample, R (Ω) is the internal resistance of each test sample, and R _{contact resistance} (Ω) is the contact resistance obtained in FIG. based on. The results are shown in FIG.

[Example 5]
In Example 5, the contact resistance, internal resistance, and electrical conductivity of a Bi ₂ Te ₃ nanowire array as a sample were evaluated using the sample stage of the present invention. The Bi ₂ Te ₃ nanowire array was prepared in the same procedure as the sample of Example 3 except that the area was different. In Example 5, the measurement was performed in the same procedure as in Example 4. The results are shown in FIG. 28 and FIG. The electrical conductivity of one Bi ₂ Te ₃ nanowire was calculated from the thermoelectric characteristics of the obtained Bi ₂ Te ₃ nanowire array. The results will be described later.

[Comparative Example 6]
In Comparative Example 6, the contact resistance, internal resistance and electrical conductivity of a Bi ₂ Te ₃ nanowire array were evaluated as samples using the sample stage of the present invention. Bi ₂ Te ₃ nanowire arrays were prepared in the same procedure as the sample of Example 3 except that the thickness was different. Comparative Example 6 uses the two-terminal method except that the connection state of the power supply is directly connected to the first thermocouple and the second thermocouple that are exposed to the outside from the sample stage. It measured in the procedure of. The results are shown in FIG. 29 and FIG.

  Details of the samples of Example 4, Example 5, and Comparative Example 6 and a list of measurement environments are shown in Table 3 for simplicity, and the results will be described.

FIG. 26 is a diagram illustrating the length dependency of the resistance of the Bi ₂ Te _2.85 Se _0.15 block according to the fourth embodiment.

The resistance value decreased with decreasing sample length. Further, FIG. 26 was swept out, and the resistance value when the length was 0, that is, the Y intercept in FIG. 26 was read. As a result, the contact resistance was 0.0020Ω. When the contact resistance per unit area of the sample was determined from this value, it was 1.2 × 10 ⁻² Ωcm ⁻² .

FIG. 27 is a diagram illustrating the cross-sectional area dependency of the electrical conductivity of the Bi ₂ Te _2.85 Se _0.15 block according to Example 4.

The contact resistance obtained in FIG. 26 is applied to the relational expression σ = L / {(RR _{contact resistance} ) A}, and the dependence of the electric conductivity of the Bi ₂ Te _2.85 Se _0.15 block on the cross-sectional area is expressed. Examined. According to FIG. 27, it was found that the electrical conductivity of the Bi ₂ Te _2.85 Se _0.15 block does not show the cross-sectional area dependence and is constant.

  26 and 27, the internal resistance and contact resistance of the sample can be calculated by performing the method of FIGS. 10 and 11 using the thermoelectric characteristic evaluation apparatus having the sample stage of FIG. It was shown that the conductivity can be calculated.

28 is a diagram showing an IV curve of a Bi ₂ Te ₃ nanowire array according to Example 5. FIG.
29 is a diagram showing an IV curve of a Bi ₂ Te ₃ nanowire array according to Comparative Example 6. FIG.

  FIG. 28A is a schematic diagram of the thermoelectric characteristic evaluation apparatus used in Example 5, which is the same as the thermoelectric characteristic evaluation apparatus 900 shown in FIG. FIG. 29A is a schematic diagram of a thermoelectric property evaluation apparatus based on the two-terminal method used in Comparative Example 6. It can be seen that the connection state of the power source is different from that of Example 5. FIG.

According to both FIG. 28B and FIG. 29B, the IV curve of the Bi ₂ Te ₃ nanowire array shows a linear relationship between voltage and current, and good ohmic contact is formed. I understand that. However, when examining the internal resistance and electrical conductivity in more detail, it was found that these results differed greatly.

The IV curve in FIG. 28B is represented by y = 0.00038572 + 0.0025407x (R = 0.99995). The slope is the internal resistance of the Bi ₂ Te ₃ nanowire array and was 0.0025Ω. On the other hand, the IV curve in FIG. 29B is represented by y = 1.1 + 4.2x (R = 0.99994). The slope is the internal resistance of the Bi ₂ Te ₃ nanowire array including the resistance of the used wire, which was 3.3Ω corrected for the resistance of the used wire. In both cases, x is a current value, and y is a voltage value.

Measuring the contact resistance of a Bi ₂ Te ₃ nanowire array is difficult because the thickness cannot be controlled. Therefore, the total contact resistance per unit area (1.2 × 10 ⁻² Ωcm ⁻² ) of the Bi ₂ Te _2.85 Se _0.15 block obtained in Example 4 was applied, and a Bi ₂ Te ₃ nanowire array was applied. The contact resistance was calculated. As a result, the contact resistances of the Bi ₂ Te ₃ nanowire arrays in FIGS. 28B and 29B were 5.8 × 10 ⁻⁵ (Ω) and 2.3 × 10 ⁻⁴ (Ω), respectively. there were. The contact resistance of the Bi ₂ Te ₃ nanowire array of FIGS. 28B and 29B corresponds to 2.3% and 0.0% of the internal resistance of the Bi ₂ Te ₃ nanowire array, respectively. I understood. Bi ₂ Te ₃ the difference between the contact resistance of the internal resistance and _Bi 2 Te ₃ nanowire array of nanowire arrays (R-R _{contact resistance)} is the resistance of the _Bi 2 Te ₃ nanowire array.

Next, the calculated internal resistance and the contact resistance obtained in FIG. 26 are applied to the relational expression σ = {L} / {(RR _{contact resistance} ) A}, respectively, and the electric conduction of the Bi ₂ Te ₃ nanowire array. I asked for a degree. Here, L of _Bi 2 Te ₃ nanowire array of FIG. 28 (B) and FIG. 29 (B) are each in the 50μm and 60 [mu] m, A, respectively, met 0.01 cm ² and 0.04 cm ² It was. As a result, it's _Bi 2 Te ₃ nanowire array of _Bi 2 Te ₃ nanowire electrical conductivity and Comparative Example 6 of the array of Example 5, respectively, were 156S / cm and 0.4 S / cm. The reason why different electrical conductivities were obtained for the same sample will be described.

  FIG. 30 is a diagram illustrating a state of current flowing through the sample according to Example 5 and Comparative Example 6.

  FIG. 30A shows the state of the current I flowing through the sample according to Example 5, and FIG. 30B shows the state of the current I flowing through the sample according to Comparative Example 6. As shown in FIG. 30 (A), when the thermoelectric property evaluation apparatus of the present invention is used, the power source is not directly connected to the first thermocouple and the second thermocouple, so that the current is uniformly distributed over the entire sample. Is spreading and flowing. On the other hand, as shown in FIG. 30B, when the thermoelectric property evaluation apparatus using the two-terminal method is used, the power source is directly connected to the first thermocouple and the second thermocouple. Current is concentrated in the area. From this, it can be seen that the electrical conductivity obtained in Example 5 is much more accurate than the electrical conductivity obtained in Comparative Example 6.

  From the above FIG. 28 to FIG. 30, by using the thermoelectric characteristic evaluation apparatus having the sample stage of FIG. 1 and performing the method of FIG. 10 and FIG. 11, the internal resistance and contact resistance of the sample can be calculated. It was shown that the conductivity can be calculated with high accuracy. In particular, it has been found that the thermoelectric property evaluation apparatus of the present invention, which is different from the usual two-terminal method, is suitable for evaluating thermoelectric properties.

Result of observation of the _Bi 2 Te ₃ nanowire array according to Example 5 with a scanning electron microscope, _Bi 2 Te ₃ nanowire density of _Bi 2 Te ₃ nanowire array was 48%. Therefore, _Bi 2 Te ₃ nanowires one average electrical conductivity in _Bi 2 Te ₃ nanowire arrays were calculated to 325S / cm. Similarly, since the Bi ₂ Te ₃ nanowire array has nanowires arranged in parallel, the absolute Seebeck coefficient (−50 μV / K) at room temperature of the Bi ₂ Te ₃ nanowire array obtained in Example 3 is Bi ₂ Te. _It can be said that it is an average absolute Seebeck coefficient of one ₃ nanowire. The output factors (S ² σ) of the Bi ₂ Te ₃ nanowire array and Bi ₂ Te ₃ nanowire were calculated from these electrical conductivities and absolute Seebeck coefficients, which were 39 μW / mK ² and 81 μW / mK ² , respectively.

[Example 7]
In Example 7, the absolute Seebeck coefficient and the open circuit voltage of a Bi ₂ Te ₃ nanowire array were evaluated as samples using the sample stage of the present invention. The thickness and size (area) of the Bi ₂ Te ₃ nanowire array were 50 μm and 0.04 cm ² , respectively. A Bi ₂ Te ₃ nanowire array was fabricated as follows. Porous aluminum oxide (Watman®) having nanoholes with a diameter of 200 nm was used as a template, and electrochemical deposition was used for the growth of Bi ₂ Te _{3 in} the nanoholes of the template. The electrodeposition mechanism of Bi ₂ Te ₃ is due to the following chemical reaction that occurs in an acidic solution.
3HTeO ₂ ⁺ + 2Bi ³⁺ + 18e ⁻ + 9H ⁺ → Bi ₂ Te ₃ (s) + 6H ₂ O
The electrochemical deposition time is different from the fabrication process of the Bi ₂ Te ₃ nanowire array of Example 3.

Using the thermoelectric property evaluation apparatus used in Example 3, a temperature gradient is formed in the thickness direction of the Bi ₂ Te ₃ nanowire array according to steps S610 to S640 of FIG. 7, and the temperature difference and potential difference at that time are formed. And the absolute Seebeck coefficient was determined. These steps were repeated twice for different temperature gradients (step S710 in FIG. 7). Here, the temperature on the first block side was changed to room temperature (300K), 330K, and 367K. The results are shown in FIG. The measurement atmosphere was in He gas decompressed to 0.09 MPa.

  Next, the relationship between the absolute Seebeck coefficient obtained in FIG. 31 and the temperature was fitted using Kaleida Graph (step S720 in FIG. 7). The equation obtained by fitting was definitely integrated into the temperature range to calculate the open circuit voltage (step S730 in FIG. 7). The results are shown in FIG.

[Comparative Example 8]
In Comparative Example 8, the open circuit voltage of a Bi ₂ Te ₃ nanowire array as a sample was evaluated using a dimensionless figure of merit. The results will be described later.

FIG. 31 is a graph showing the relationship between the absolute Seebeck coefficient and the temperature of the Bi ₂ Te ₃ nanowire array according to Example 7.

According to FIG. 31, the absolute value of the absolute Seebeck coefficient of the Bi ₂ Te ₃ nanowire array increased with increasing temperature.

The formula obtained by the fitting is shown in FIG. Let this equation be S _(T) . As shown in the following equation, S _(T) is definitely integrated between the high temperature part 308K assuming the body temperature and the low temperature part 298K assuming the outside air temperature. As a result, the open circuit voltage at this temperature difference is calculated as 606 μV. It was.

On the other hand, according to Comparative Example 8, the Seebeck coefficient S at the high-temperature part temperature is an evaluation that approximates the absence of temperature dependence of the thermoelectric characteristics based on the dimensionless figure of merit ZT used as an index for evaluating the characteristics of the thermoelectric material. _The open circuit voltage, which is the product of _HOT and the temperature difference ΔT, was calculated to be 630 μV.

Calculation ∫ ₂₉₈ of the open circuit voltage according to the present invention using a fitting according to Example 7 ³⁰⁸ S _T dT = 606μV
Calculation method of open circuit voltage approximating temperature dependence according to comparative example 8 S ₃₀₈ ΔT = 630 μV

  The open circuit voltages obtained in Example 7 and Comparative Example 8 showed a difference of 3.8%. This difference was found to correspond to a difference of 7.5% at maximum output.

FIG. 32 is a diagram showing the temperature dependence of the open circuit voltage of the Bi ₂ Te ₃ nanowire array according to Example 7 and Comparative Example 8.

  In FIG. 32, ● represents the calculation result using the fitting according to Example 7, and □ represents the calculation result obtained by approximating the temperature dependence according to Comparative Example 8. FIG. 32 shows the open circuit voltage when the low temperature part is fixed at 300 K and the high temperature part is changed. According to FIG. 32, the larger the temperature difference, that is, the higher the temperature of the high temperature part, the more the open circuit voltage using the fitting according to Example 7 and the open circuit voltage approximating the temperature dependence according to Comparative Example 8. The difference from the value of became larger. This is because the open circuit voltage calculation method using fitting according to Example 7 considers the temperature dependence of the Seebeck coefficient shown in FIG. 31, but the open circuit voltage approximated to the temperature dependence according to Comparative Example 8 is considered. This is because the calculation method does not consider the temperature dependence of the Seebeck coefficient.

  FIG. 31 and FIG. 32 show that the open circuit voltage of the sample can be calculated with high accuracy by performing the method of FIG. 7 using the thermoelectric characteristic evaluation apparatus having the sample stage of FIG. In particular, the method of FIG. 7 of the present invention was shown to be more accurate than the evaluation using the existing dimensionless figure of merit ZT.

[Example 9]
In Example 9, the open circuit voltage of the Ni plate as a sample was evaluated using the sample stage of the present invention. The Ni plate was the same as the sample of Example 2. In addition to the thermoelectric characteristic evaluation apparatus used in Example 4, a thermoelectric characteristic evaluation apparatus further including a temperature gradient hand was used. Specifically, a Peltier heater / cooler (manufactured by Kelk) was provided as temperature gradient means 310a, 310b on current terminals 910a, 910b respectively installed in the first block 130a and the second block 130b. Such a configuration is the same as that of the thermoelectric property evaluation apparatus 1300 described with reference to FIG. The measurement atmosphere was in the air.

  Specifically, the first block side is the high temperature side, the second block side is the low temperature side, and the temperatures of (high temperature side (K) and low temperature side (K)) are the conditions 1 (297.46), respectively. , 296.40), condition 2 (304.26, 301.96), condition 3 (315.44, 31.11.90) and condition 4 (333.21, 328.56). The IV curve was measured and the output was determined. The results are shown in FIG.

  FIG. 33 is a diagram showing an IV curve and an output curve at each temperature difference of the Ni plate according to Example 9.

The output was calculated using an IV curve. According to FIG. 33, both the IV curve and the output curve of the Ni plate increased as the temperature difference increased. Next, in the same manner as in Example 7, the relationship between the absolute Seebeck coefficient and temperature (not shown) was fitted using Kaleida Graph, and the obtained temperature dependence equation S _(T) was used for each condition. The open circuit voltage at was calculated. The results are summarized in Table 4.

Table 4, for reference, in the same manner as in Comparative Example 8 also shows the results of calculating the open circuit voltage is approximated the temperature dependence of _{(S hot ΔT (μV))} . Further, Table 4 also shows the potential difference (actual value of the open circuit voltage) when the current value under each condition is 0, based on FIG.

According to Table 4, the value of the open circuit voltage using fitting ( _∫Tcold ^Shot S _(T) dt (μV)) was smaller than that of the open circuit voltage approximating the temperature dependence. The measured value of the open circuit voltage was smaller than both the open circuit voltage using the fitting and the open circuit voltage approximating the temperature dependence, but it was found to be closer to the value of the open circuit voltage using the fitting. .

  From the above FIG. 33 and Table 4, it was shown that the open circuit voltage of the sample can be calculated with high accuracy by performing the method of FIG. 7 using the thermoelectric characteristic evaluation apparatus provided with the sample stage of FIG. In particular, the method of FIG. 7 of the present invention was shown to be more accurate than the evaluation using the existing dimensionless figure of merit ZT.

[Example 10]
In Example 10, it was evaluated effective maximum output _{P max} and a maximum power density _{P A} of _Bi 2 Te ₃ nanowire array as a sample by using a sample stage of the present invention. The Bi ₂ Te ₃ nanowire array was the same as the sample of Example 5. The thermoelectric property evaluation apparatus used was the same as that used in Example 9.

  Specifically, the sample was sandwiched between the first block and the second block in the thickness direction, and current was applied to the sample (step S1010 in FIG. 14). The potential difference of the sample was measured (Step S1020 in FIG. 14). These were repeated (step S1030 in FIG. 14). These were performed on samples of each length, and the resistance was calculated from the current value and the potential difference (step S1040 in FIG. 14). The operations up to here were the same as in Example 5, and the internal resistance R was 0.0025Ω.

Next, a temperature gradient was formed on the sample (step S1410 in FIG. 14). The temperature gradient is such that the first block side is the high temperature side (24.70 ° C., 297.85 K), the second block side is the low temperature side (23.31 ° C., 296.46 K), and 1.39 ° C. (1 .39K) temperature gradient was formed. Next, the potential difference between the samples was measured (step S1420 in FIG. 14). The potential difference obtained here corresponds to an open circuit voltage and was −75 μV. The effective maximum output _Pmax was calculated according to the following equation.

P _max = {(ΔE) ² × L} / {4 × R × A}
Here, the open circuit voltage ΔE (μV) is −75 μV, the sample length L (cm) is 0.005 cm, the internal resistance R (Ω) is 0.0025Ω, and the sample cross-sectional area A (cm ² ) is 0. When 01 cm ² was substituted, P _max = 0.028 μW / cm was obtained.

Next, consists the _Bi 2 Te ₃ nanowire array, the filling factor of _Bi 2 Te ₃ nanowire array assumes module is 80%, was calculated the maximum output density _{P A} according to the following equation.

P _A = {(P _{max (n)} + P _{max (p)} ) × a} / (2 × L)
Here, the effective maximum output P _{max (n)} of the n-type thermoelectric material is 0.028 μW / cm, the effective maximum output P _{max (p)} of the p-type thermoelectric material is 0 (not assumed in this embodiment), filling When 80% was substituted as the rate a (%) and 0.005 cm was substituted as the length L (cm) of the sample, P _A = 22 μW / cm ² was obtained.

  If the thermoelectric characteristics of the sample are evaluated using the sample stage of the present invention, the thermoelectric characteristics can be obtained with high accuracy regardless of the size of the sample, which is suitable for the thermoelectric characteristic evaluation apparatus and its evaluation method. In addition, the use of the sample stage of the present invention is advantageous because the electrode for the sample can be evaluated. The thermoelectric property evaluation method of the present invention can evaluate not only the electrical conductivity and Seebeck coefficient, which are factors of the figure of merit used in the material research field, but also the output used in the systematization research. It can be used as a comprehensive evaluation method used for industrialization and industrialization.

Claims (29)

A sample stage for sandwiching a sample and evaluating the thermoelectric characteristics of the sample,
A first block embedded with a first thermocouple that is insulated except for the tip;
A second block embedded with a second thermocouple insulated except for the tip, and
The first block and the second block sandwich the sample such that the tips of the first thermocouple and the second thermocouple are in contact with the sample,
The space between the first thermocouple and the first block other than the region where the first thermocouple and the sample are in contact, and the region other than the region where the second thermocouple and the sample are in contact with each other A space between the second thermocouple and the second block is filled with a conductive material;
The first thermocouple goes out from the planar end of the first block to be connected to a voltmeter,
The sample stage, wherein the second thermocouple is exposed to the outside from an end in a planar direction of the second block so as to be connected to the voltmeter.   2. The sample stage according to claim 1, wherein the material satisfies an absolute value of an absolute Seebeck coefficient at room temperature of 0 μV / K or more and 20 μV / K or less.   The material is Au, Al, Ag, Co, Cr, Cu, Fe, In, Ir, Mg, Mo, Ni, Pd, Pt, Ru, Su, Ti, W, Zn, and at least one of them. The sample stage according to claim 2, wherein the sample stage is selected from the group consisting of containing alloys.   The material is at least one selected from the group consisting of Au, Al, Ag, Co, Cr, Cu, Fe, In, Ir, Mg, Mo, Ni, Pd, Pt, Ru, Su, Ti, W, and Zn. The sample stage according to claim 2, which is an intermetallic compound containing a metal.   2. The sample stage according to claim 1, wherein the first block and the second block are made of a thermally conductive material having a thermal conductivity of 65 W / (m · K) or more at room temperature.   The first block and the second block are Au, Al, Ag, Co, Cr, Cu, Fe, In, Ir, Mg, Mo, Ni, Pd, Pt, Ru, Su, Ti, W, Zn The sample stage according to claim 5, wherein the sample stage is selected from the group consisting of an alloy containing at least one of these.   The first block and the second block are Au, Al, Ag, Co, Cr, Cu, Fe, In, Ir, Mg, Mo, Ni, Pd, Pt, Ru, Su, Ti, W, and Zn. The sample stage according to claim 5, which is an intermetallic compound containing at least one metal selected from the group consisting of:   The sample stage according to claim 1, wherein the first thermocouple and the second thermocouple are in contact with a sample provided with an electrode.   The sample stage according to claim 8, wherein the electrode has a thickness of 400 nm or more.   The sample stage according to claim 1, which is accommodated in an external heater. A sample stage for sandwiching the sample and evaluating the thermoelectric properties of the sample;
A temperature gradient means for forming a temperature gradient in the sample;
A voltmeter for measuring a potential difference between the samples,
The sample stage is the sample stage according to any one of claims 1 to 10,
The voltmeter includes the first thermocouple that exits from the planar end of the first block to the outside, and the second thermoelectric that exits externally from the planar end of the second block. Thermoelectric property evaluation device connected to a pair.   The temperature gradient means includes a heating device provided on a side facing the sample of the first block, and a cooling device provided on a side facing the sample of the second block. The thermoelectric property evaluation apparatus according to claim 11, comprising:   The thermoelectric characteristic evaluation apparatus according to claim 11, further comprising a switch that opens and closes a voltage measurement circuit including the sample and the voltmeter. A power source for applying a current to the sample;
The thermoelectric characteristic evaluation apparatus according to claim 12, wherein the power source is connected via a current terminal formed of a conductive wire wound around the first block and the second block. A power source for applying a current to the sample;
The said power supply is connected via the current terminal respectively installed between the said 1st block and the said heating apparatus, and between the said 2nd block and the said cooling device. Thermoelectric property evaluation equipment. The current terminal comprises a block around which a conductive wire is wound,
The thermoelectric property evaluation apparatus according to claim 15, wherein the block is made of a heat conductive material having a thermal conductivity of 65 W / (m · K) or more at room temperature. A sample stage for sandwiching the sample and evaluating the thermoelectric properties of the sample;
A voltmeter for measuring a potential difference between the samples;
A power source for applying a current to the sample,
The sample stage is the sample stage according to any one of claims 1 to 10,
The voltmeter includes the first thermocouple that exits from the planar end of the first block to the outside, and the second thermoelectric that exits externally from the planar end of the second block. Connected to the pair,
The thermoelectric property evaluation apparatus, wherein the power source is connected via current terminals made of conductive wires wound around the first block and the second block, respectively. A sample stage for sandwiching the sample and evaluating the thermoelectric properties of the sample;
A voltmeter for measuring a potential difference between the samples;
A power source for applying a current to the sample,
The sample stage is the sample stage according to any one of claims 1 to 10,
The voltmeter includes the first thermocouple that exits from the planar end of the first block to the outside, and the second thermoelectric that exits externally from the planar end of the second block. Connected to the pair,
The power source is connected via current terminals provided on the side of the first block facing the sample and the side of the second block facing the sample and the side of the second block facing the sample. Thermoelectric property evaluation device. The current terminal comprises a block around which a conductive wire is wound,
The thermoelectric property evaluation apparatus according to claim 18, wherein the block is made of a heat conductive material having a thermal conductivity of 65 W / (m · K) or more at room temperature. A method for evaluating thermoelectric properties of a sample using the sample stage according to any one of claims 1 to 10,
Sandwiching a sample provided with an electrode between the first block and the second block to form a temperature gradient in the sample;
Measuring a potential difference and a temperature difference between the samples generated by the formed temperature gradient;
Repeating the steps of forming the temperature gradient and measuring the potential difference and the temperature difference;
Calculating an absolute Seebeck coefficient based on the following equation: S = と E / ∇T + S _thermocouple (where S (μV / K) is the absolute Seebeck coefficient, and ∇T (K) and ∇E (μV ) Are a change in temperature difference and a change in potential difference between the samples obtained by the repeating step, respectively, and the S _thermocouple (μV / K) is the first thermocouple and the second thermocouple. Is the Seebeck coefficient of the material comprising
Including the method.   The method according to claim 20, wherein the step of forming the temperature gradient and the step of measuring the potential difference and the temperature difference are performed in air, oxygen, vacuum, inert gas atmosphere or wet gas atmosphere. Forming the temperature gradient, measuring the potential difference, repeating the step, and calculating the absolute Seebeck coefficient at least two times for different temperatures; and
Plotting and fitting the absolute Seebeck coefficient obtained by repeating two or more steps against temperature;
21. The method of claim 20, further comprising: integrating the temperature dependence expression of the absolute Seebeck coefficient obtained by the fitting over the measured temperature range to calculate an open circuit voltage. A method for evaluating thermoelectric properties of a sample using the sample stage according to any one of claims 1 to 10,
Sandwiching a sample provided with an electrode between the first block and the second block, and applying a current to the sample;
Measuring a potential difference between samples to which the current is applied;
Repeating the steps of applying the current and measuring the potential difference;
Calculating the internal resistance of the sample based on the following formula: R = ∇V / ∇I (where R is the internal resistance of the sample and ∇I (A) is obtained in the repeating step. And 電流 V is a change in potential difference between the samples obtained in the repeating step.)
Including the method.   The method according to claim 23, wherein the step of applying the current and the step of measuring the potential difference are performed in air, oxygen, vacuum, inert gas atmosphere or wet gas atmosphere. Step of calculating electric conductivity of the sample based on the following formula: σ = L / {(RR _{contact resistance} ) A} (where σ (S / cm) is the electric conductivity of the sample, L (cm) is the length of the sample, A (cm ² ) is the cross-sectional area of the sample, R (Ω) is the internal resistance of the sample, and R _{contact resistance} (Ω) is Resistance value between the sample and the electrode, resistance value of the material constituting the electrode, resistance value between the electrode and the first thermocouple, between the electrode and the second thermocouple Resistance value and the total resistance value of the materials constituting the first thermocouple and the second thermocouple)
25. A method according to any of claims 23 or 24, further comprising: The R _{contact resistance} (Ω) is a resistance value when the length of the sample is 0 when plotting a change in resistance value with respect to the length of the sample (provided that the cross-sectional area of the sample is constant). 26. The method of claim 25, wherein: Forming a temperature gradient in the sample;
Measuring a potential difference between the samples generated by the formed temperature gradient;
Calculating the effective maximum output of the sample based on the following formula: P _max = {(ΔE) ² × L} / {4 × R × A} (where P _max is the effective maximum output of the sample) ΔE (μV) is the potential difference between the samples obtained in the step of measuring the potential difference, L (cm) is the length of the sample, and R (Ω) is the inside of the sample Resistance, and A (cm ² ) is the cross-sectional area of the sample)
25. A method according to any of claims 23 or 24, further comprising: The sample is a module including one or more elements made of an n-type thermoelectric material and / or a p-type thermoelectric material,
Step of calculating the maximum output density of the sample based on the following formula: P _A = {(P _{max (n)} + P _{max (p)} ) × a} / (2 × L) (where P _A is The maximum output density of the sample, P _{max (n)} is the effective maximum output of the n-type thermoelectric material, P _{max (p)} is the effective maximum output of the p-type thermoelectric material, and a (%) is The filling rate of the n-type thermoelectric material and / or p-type thermoelectric material in the module, and L (cm) is the length of the n-type thermoelectric material and / or p-type thermoelectric material)
28. The method of claim 27, further comprising: A method for evaluating an electrode used for a thermoelectric material, using the sample stage according to claim 1,
A sample made of a thermoelectric material provided with an electrode and having different lengths (however, the cross-sectional area of the sample is constant) is sandwiched between the first block and the second block, and a current is passed through the sample. Applying, and
Measuring a potential difference between samples to which the current is applied;
Repeating the steps of applying the current and measuring the potential difference;
Calculating the resistance of the sample based on the following equation;
R = ∇V / ∇I (where R is the internal resistance of the sample, ∇I (A) is the change in current value obtained in the repeating step, and ∇V is the repeating step) (This is the change in the potential difference obtained in.)
Plotting resistance against the length of the sample and reading the resistance when the length of the sample is zero.