JP2011185697A - Thermoelectric material evaluation device and thermoelectric characteristic evaluation method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a thermoelectric material evaluation device having a simple and inexpensive device constitution and capable of obtaining a measuring result of high precision in a short time, and a thermoelectric characteristic evaluation method. <P>SOLUTION: The thermoelectric characteristic evaluation device 1 is constituted so that the edge faces Se of a measuring sample S are supported by a pair of blocks 11 so as to be nipped by first and second electrodes 14 and 15, a temperature gradient is formed in the measuring sample S, the thermoelectric capacity α of the measuring sample S is calculated on the basis of the thermoelectromotive force of the measuring sample S, which is measured by a voltmeter 16 in a state that a switch 18 is opened, and the temperature difference between the edge faces Se of the measuring sample S measured by thermocouples 21 and 22, the switch 18 is closed after the thermoelectromotive force of the measuring sample S is generated to perform discharge and the resistivity ρ of the measuring sample S is calculated on the basis of the voltage drop ΔV of the measuring sample S measured by the voltmeter 16 and the current value I measured by an ammeter 17. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

The present invention relates to a thermoelectric material evaluation apparatus and a thermoelectric property evaluation method for evaluating the thermoelectric power and resistivity of a thermoelectric material.

Conventionally, the direct current four-terminal method shown in FIG. 6 is generally used as a method for evaluating the thermoelectric characteristics of thermoelectric materials. The measurement sample S is in a state where the end surface Se is sandwiched between the upper low temperature side electrode block 111 and the lower high temperature side electrode block 111 in which the heater 112 is built in the measurement tank 130 maintained at a constant temperature by the external heater 131. Set. The temperature of the high temperature side electrode block 111 is set to be about 10 ° C. higher than the temperature of the low temperature side electrode block 111, and the thermoelectromotive force is generated in the measurement sample S in the direction of the temperature gradient. Thermocouples 121 and 122 are in contact with the side surface of the measurement sample S via a distance L, and a temperature difference ΔT (= T1−T2) therebetween and a potential difference V1 by a voltmeter 116 using the same thermocouple. Measured. The thermoelectric power α is calculated by the following formula from these measurement results.

(Equation 1)
α = V1 / ΔT

Resistivity ρ is a constant amount of current value I supplied from a constant current power supply 140 connected to the low temperature side and high temperature side electrode block 111 and a potential difference detected by a thermocouple contacting the measurement sample via a distance L. Based on V2, it is calculated by the following equation. Here, A is a cross-sectional area of the measurement sample.

(Equation 2)
ρ = V2 · A / I / L

For example, Patent Documents 1 and 2 disclose thermoelectric characteristic evaluation methods based on a DC four-terminal method.

JP 2003-57121 A Japanese Patent Laid-Open No. 7-324991

However, the measurement methods as described above have the following problems.
(1) In the resistivity measurement, it is necessary to energize for a short time in order to avoid the influence on the measurement result due to the Peltier effect and Joule heat. For example, an expensive constant current power source capable of pulse energization must be used. The system must be complicated and expensive.
(2) In voltage measurement with a thermocouple, since the thermocouple and the measurement sample are in point contact, the influence of the oxide film on the surface of the measurement sample and the non-uniformity of the material structure may affect the measurement result.
(3) Although it is necessary to uniformly heat the entire system including the measurement sample and the electrode block in order to reduce the influence of the temperature change on the measurement result, it takes time until the temperature is stabilized and the measurement can be started. In addition, since the entire system is uniformly heated, the heat capacity is increased, and it takes time to perform measurement at different temperatures.
(4) In temperature measurement and voltage measurement, since the thermocouple is brought into contact with the side surface of the measurement sample, the length of the measurement sample that can be used is limited to about 5 mm. In recent years, demand for thermoelectric property evaluation such as elements of π-type thermoelectric power generation modules has increased, but measurement samples of these materials are small in size, for example, it is necessary to measure measurement samples having a length of 2 to 3 mm, The DC 4 terminal method cannot be used.

Therefore, an object of the present invention is to provide a thermoelectric material evaluation apparatus that has a simple and inexpensive apparatus configuration and can obtain a highly accurate measurement result in a short time.

In order to achieve the above object, according to the first aspect of the present invention, the thermoelectric property evaluation apparatus includes a pair of blocks configured to be capable of forming a temperature difference in order to form a temperature gradient in the measurement sample. A pair of first electrodes disposed between the block and an end surface of the measurement sample, and a voltage measurement unit connected to the pair of first electrodes and measuring a voltage generated in the measurement sample; A pair of second electrodes disposed between the block and an end surface of the measurement sample in a state of being insulated from the first electrode, and a current flowing through the measurement sample connected to the pair of second electrodes A current measuring means for measuring the current, a switch for opening and switching a current measuring circuit comprising the measurement sample, the pair of second electrodes and the current measurement means, and a temperature measurement in the vicinity of the end face of the measurement sample Temperature measuring means for performing The thermoelectric power of the measurement sample is calculated based on the thermoelectromotive force of the measurement sample measured by the voltage measurement means and the temperature difference of the end face of the measurement sample measured by the temperature measurement means with the chamber open. After the thermal electromotive force is generated, the switch is closed and discharged, the voltage drop of the measurement sample measured by the voltage measurement means, and the resistivity of the measurement sample based on the current value measured by the current measurement means And a technical means including a calculating means for calculating.

According to the first aspect of the present invention, the end face of the measurement sample is sandwiched between the first electrode and the second electrode and supported by the pair of blocks, a temperature gradient is formed in the measurement sample, and the voltage is opened with the switch open. After calculating the thermoelectric power of the measurement sample based on the thermoelectromotive force of the measurement sample measured by the measurement means and the temperature difference of the end surface of the measurement sample measured by the temperature measurement means, and generating the thermoelectromotive force of the measurement sample The resistivity of the measurement sample can be calculated on the basis of the voltage drop of the measurement sample measured by the voltage measurement means and the current value measured by the current measurement means after the switch is closed and discharged.
In the measurement of resistivity, since a discharge generated in a short time by closing the switch using the thermoelectromotive force of the measurement sample is used, there is no need 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.

According to a second aspect of the present invention, in the thermoelectric characteristic evaluation apparatus according to the first aspect, the technical means that the current measuring circuit includes a variable resistor having a variable resistance value is used.

According to the invention described in claim 2, since the current measuring circuit includes a variable resistor whose resistance value is variable, different resistance values are set in the variable resistor, and the current value and voltage are set in each setting. The drop can be measured, and the resistivity can be calculated based on the current value and voltage drop corresponding to each resistance value. According to this, the influence of the resistance of the current measurement circuit can be canceled and the resistivity is calculated based on a plurality of current values and voltage drops corresponding to each resistance value, so that the error of each measured value is reduced. Therefore, the resistivity can be measured with high accuracy.
In addition, if the resistance value of the measurement sample is small, the voltage drop is small and it is difficult to measure with high accuracy. However, high-precision measurement can be performed by setting an appropriate resistance value using a variable resistor.

According to a third aspect of the present invention, in the thermoelectric property evaluation apparatus according to the first or second aspect, the temperature measuring means is provided in contact with the end surface of the measurement sample through the block. Use technical means.

According to the invention described in claim 3, since the temperature measuring means is provided through the block and in contact with the end face of the measurement sample, the measurement sample having a short length, which is difficult in the DC four-terminal method, is provided. Thermoelectric property evaluation can be performed.

According to a fourth aspect of the present invention, in the thermoelectric characteristic evaluation apparatus according to any one of the first to third aspects, the pair of blocks each incorporate temperature control means capable of temperature control. The technical means is used.

According to the fourth aspect of the present invention, since the pair of blocks each include temperature control means capable of temperature control, the measurement sample can be controlled to reach the measurement temperature in a short time. .

According to a fifth aspect of the present invention, the thermoelectric property evaluation apparatus according to any one of the first to fourth aspects is used, and the pair of the measurement sample is sandwiched between the first electrode and the second electrode. The step of forming a temperature gradient on the measurement sample, the step of measuring the temperature difference of the end face of the measurement sample by the temperature measuring means, and the current measuring circuit being opened by the switch, A step of measuring the thermoelectromotive force of the measurement sample by the voltage measuring means, and a step of calculating the thermoelectric power based on the temperature difference between the thermoelectromotive force and the end face of the measurement sample measured by the temperature measuring means by the computing means. And switching the current measurement circuit from the open state to the connected state by the switch to discharge the thermoelectromotive force of the measurement sample, and measuring the current value flowing through the measurement sample by the current measurement means Measuring a voltage drop by the voltage measuring means, thermoelectric characteristic evaluation method comprising the steps, a to calculate the resistivity based on the current value and the voltage drop by the calculating means, using the technical means of.

According to the invention described in claim 5, the end face of the measurement sample is supported by the pair of blocks sandwiched between the first electrode and the second electrode, a temperature gradient is formed in the measurement sample, and the voltage is applied with the switch open. After calculating the thermoelectric power of the measurement sample based on the thermoelectromotive force of the measurement sample measured by the measurement means and the temperature difference of the end surface of the measurement sample measured by the temperature measurement means, and generating the thermoelectromotive force of the measurement sample The resistivity of the measurement sample can be calculated on the basis of the voltage drop of the measurement sample measured by the voltage measurement means and the current value measured by the current measurement means after the switch is closed and discharged.
In the measurement of resistivity, since a discharge generated in a short time by closing the switch using the thermoelectromotive force of the measurement sample is used, there is no need 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.

According to a sixth aspect of the present invention, in the thermoelectric characteristic evaluation method according to the fifth aspect, the thermoelectric characteristic evaluation apparatus according to any one of the second to fourth aspects, wherein the variable resistor is provided. Using the thermoelectric characteristic evaluation apparatus, different resistance values are set in the variable resistor, current values and voltage drops are measured in the respective settings, and the resistivity is calculated based on the current value and voltage drop corresponding to each resistance value. The technical means of calculating is used.

According to the sixth aspect of the present invention, different resistance values are set in the variable resistor, the current value and the voltage drop are measured in each setting, and the resistance is determined based on the current value and the voltage drop corresponding to each resistance value. The rate can be calculated. According to this, the influence of the resistance of the current measurement circuit can be canceled, and the resistivity is calculated based on a plurality of current values and voltage drops according to each resistance value. Since the error can be reduced, the resistivity can be measured with high accuracy.
In addition, if the resistance value of the measurement sample is small, the voltage drop is small and it is difficult to measure with high accuracy. However, high-precision measurement can be performed by setting an appropriate resistance value using a variable resistor.

It is a block diagram of the thermoelectric property evaluation apparatus of this invention. It is a plane explanatory view showing arrangement of the 1st electrode and the 2nd electrode. It is explanatory drawing of the measuring method of a resistivity. It is explanatory drawing which compares the result of having performed the thermoelectric characteristic evaluation of P-type BiTe by the method of this invention and the method of this invention. 4A shows the measurement result of thermoelectric power, and FIG. 4B shows the measurement result of resistivity. It is explanatory drawing which compares the result of having performed the thermoelectric property evaluation of N type BiTe by the method of this invention and the method of this invention. FIG. 5A shows a measurement result of thermoelectric power, and FIG. 5B shows a measurement result of resistivity. It is a block diagram of the conventional thermoelectric characteristic evaluation apparatus (DC 4 terminal method).

Hereinafter, the thermoelectric property evaluation apparatus of the present invention will be described with reference to the drawings. In addition, this invention is not limited to the following embodiment.

As shown in FIG. 1, the thermoelectric characteristic evaluation apparatus 1 includes a pair of blocks 11 (11a and 11b) configured to be capable of forming a temperature difference in order to form a temperature gradient in the measurement sample S, and the block 11 and the measurement sample. A pair of first electrodes 14 and 14 and a pair of second electrodes 15 and 15 disposed between the end faces of S, a voltmeter 16 for measuring a voltage generated in the measurement sample S, and a measurement sample An ammeter 17 for measuring the current flowing through S, a switch 18 for switching between opening and closing of the current measurement circuit K, thermocouples 21 and 22 for measuring the temperature of the end face of the measurement sample S, and the thermoelectric of the measurement sample For example, a computing device 40 such as a personal computer.

The block 11 (11a, 11b) is formed in a substantially rectangular parallelepiped shape from a high heat conductive material, for example, a metal material such as copper or a ceramic material such as aluminum nitride. As shown in FIG. 2, the surface of the block 11 that sandwiches the measurement sample S is formed larger than the end surface Se of the measurement sample S, and the measurement sample S is supported by being sandwiched between the block 11a and the block 11b. It has become. Thereby, the in-plane temperature distribution of the end surface Se of the measurement sample S can be made uniform, and more accurate measurement can be performed. Between the end surface Se of the measurement sample S and the block 11, an insulating layer 13, a first electrode 14 and a second electrode 15 provided on the same plane are interposed in this order from the block 11 side.

Each of the blocks 11a and 11b includes temperature control means 12a and 12b such as a heater and a cooler, and is configured to be controllable to a predetermined temperature. Thereby, it is possible to control the measurement sample S so as to reach the measurement temperature in a short time. In this embodiment, the upper block 11a is used as a high temperature side block, and the lower block 11b is used as a low temperature side block.

A through-hole 11c is formed in the central portion of the block 11 in the vertical direction, and is configured so that the temperature can be measured by inserting the thermocouples 21 and 22 into contact with the end surface Se of the measurement sample S. The thermocouples 21 and 22 are connected to the arithmetic device 40 and output temperature information of the end surface Se of the measurement sample S to the arithmetic device 40. Here, based on the temperature of the end surface Se of the measurement sample S by the thermocouples 21 and 22, the temperature of the blocks 11a and 11b can also be controlled.

The insulating layer 13 is provided to insulate the first electrode 14, 14 and the second electrode 15, 15 from the block 11 when using a metal block. Insulating layer 13 is preferably formed of a material having good thermal conductivity in order to reduce thermal resistance. For example, it consists of aluminum nitride, alumina, zirconia, silicon nitride or the like. The thickness of the insulating layer 13 is preferably as thin as possible in order to reduce the thermal resistance, and more preferably 0.5 mm or less. The insulating layer 13 may be a plate-like member, but is preferably formed integrally with the block 11 by a known method such as thermal spraying or paste baking in order to reduce thermal resistance due to contact between the members. The insulating layer 13 is also formed with a hole through which the thermocouples 21 and 22 can be inserted. The insulating layer 13 may be omitted when the block 11 is an insulating material such as ceramics.

The first electrode 14 and the second electrode 15 are formed in a layer shape or a plate shape from a conductive material, and are provided in a state of being insulated from each other on the same plane. In the present embodiment, as shown in FIG. 2, the first electrode 14 and the second electrode 15 are each formed in a rectangular shape, and are spaced apart from each other while avoiding the through hole 11c. Here, in order to increase the contact area with the end surface Se of the measurement sample S, the gap between the first electrode 14 and the second electrode 15 may be set to a minimum width necessary for insulation. Since the 1st electrode 14 and the 2nd electrode 15 generate | occur | produce a thermoelectromotive force itself, it is preferable to form with a material with small Seebeck coefficients, such as gold | metal | money, copper, and silver.

The first electrode 14 and the second electrode 15 may be plate-like members or may be formed integrally with the insulating layer 13. In the case where the insulating layer 13 is formed integrally, a known method such as paste baking, thermal spraying, diffusion bonding, or plating can be used.
Furthermore, the first electrode 14 and the second electrode 15 can also be directly formed on the end surface Se of the measurement sample S.
Further, when the insulating layer 13 is unnecessary, it can be formed integrally with the block 11.

Since the surfaces of the first electrode 14 and the second electrode 15 that are in contact with the measurement sample S can be made to be smooth surfaces, sufficient contact with the measurement sample can be obtained. The influence given can be reduced. For example, the arithmetic average roughness Ra is preferably 0.8 μm or less and the flatness of 5 μm or less.

The voltmeter 16 is provided between the first electrodes 14 and 14 and measures a voltage generated between the end surfaces Se of the measurement sample S. The voltmeter 16 is connected to the arithmetic device 40 and outputs a measured voltage value to the arithmetic device 40.

The current measurement circuit K is configured such that the measurement sample S is sandwiched between the second electrodes 15 and 15, the ammeter 17 and the variable resistor 19 are connected in series, and switching of the current measurement circuit K is switched by the switch 18. It can be performed. The ammeter 17 measures the current flowing through the measurement sample S. The ammeter 17 is connected to the arithmetic device 40 and outputs a measured current value to the arithmetic device 40.

The arithmetic device 40 is a device that can be operated with storage means such as a personal computer, for example, stores the measured values of the voltmeter 16 and the ammeter 17, and based on these measured values, the thermoelectric power of the measurement sample S and Calculate resistivity.

The measurement sample S, the block 11, each electrode, and the like are accommodated in the measurement tank 30. The measurement tank 30 is configured to be able to control the measurement atmosphere such as the temperature in the tank and the atmosphere. For example, when the inside of the measurement tank 30 is in a vacuum state, the influence of heat conduction due to convection such as air is removed, and more accurate thermoelectric characteristics can be measured.

Below, the thermoelectric characteristic evaluation method using the above-mentioned thermoelectric characteristic evaluation apparatus 1 is demonstrated. The measurement sample S is formed in a columnar shape such as a prism or cylinder.

First, the measurement sample S is supported by the blocks 11a and 11b with the insulating layer 13, the first electrode 14, and the second electrode 15 interposed between the end surface Se of the measurement sample S. Then, the thermocouples 21 and 22 are inserted into the through holes 11c of the blocks 11a and 11b, respectively, and are brought into contact with the end surface Se of the measurement sample S. Since the periphery of the tips of the thermocouples 21 and 22 is maintained at a constant temperature by the heat from the blocks 11a and 11b, the temperature change due to heat transfer by the thermocouples 21 and 22 is small, and the end surface Se of the measurement sample S is reduced. The temperature can be measured with high accuracy. Further, by arranging the thermocouples 21 and 22 on the end surface Se of the measurement sample S, it is possible to evaluate the thermoelectric characteristics of the measurement sample S having a length of 5 mm or less, which is difficult with the direct current four-terminal method.

At this time, the switch 18 is open, and the current measurement circuit K is open.

Next, each of the blocks 11a and 11b is controlled to a predetermined temperature, and a temperature gradient is generated in the measurement sample S. Here, the block 11b on the high temperature side is set higher by about 5 to 30 ° C. than the block 11a on the low temperature side. Here, the measured thermoelectric power and resistivity are average values (T1 + T2) / 2 of the low temperature side temperature T1 and the high temperature side temperature T2.
Therefore, the smaller the temperature difference between the blocks 11a and 11b, the closer to the true value. However, the smaller the temperature difference, the smaller the voltage and current output values and the greater the influence on measurement errors. It sets suitably according to the thermoelectric characteristic of the measurement sample S.

Subsequently, the thermoelectromotive force V between the end surfaces Se of the measurement sample S is measured by the voltmeter 16 connected to the first electrode 14.
The measured thermoelectromotive force V is output to the computing device 40, and the computing device 40 calculates the thermoelectric power α by the following equation based on the measured voltage value V.

(Equation 3)
α = V / (T2-T1)

Subsequently, after the resistance value is set to a predetermined value (for example, Re: estimated resistance value) by the variable resistor 19, the switch 18 is closed and the current measurement circuit K is connected. Since a thermoelectromotive force is generated in the measurement sample S, a current corresponding to the resistance value R of the variable resistor 19 and the measurement sample S flows through the current measurement circuit K. An example of changes in the current value flowing through the current measurement circuit K and the voltage value of the measurement sample S is shown in FIG. When the switch 18 is closed, the current value discharged from the measurement sample S and flowing through the current measurement circuit K rapidly increases, and a voltage drop corresponding to the resistance values of the variable resistor 19 and the measurement sample S occurs. The voltage drop ΔV is measured by the voltmeter 16 connected to the first electrode 14, and the current value I flowing through the measurement sample S at that time is measured by the ammeter 17 connected to the second electrode 15, and the measured value Are respectively output to the arithmetic unit 40. The arithmetic device 40 calculates a current value I and a voltage drop ΔV for calculating the resistance value R. As shown in FIG. 4, the current value I and the voltage drop ΔV are highly reproducible when they are obtained by extrapolating the inflection points from the time change curves of the current and voltage, using values in a state where the time change is small. It can be obtained with high accuracy. The calculated current value I and voltage drop ΔV are stored in the storage means of the arithmetic device 40.

Error factors for measuring the resistance value of the measurement sample S include the Peltier effect due to the current generated by the measurement sample S and the error due to Joule heat. Although these influences are caused by the time change of the temperature of the measurement sample S, in the present embodiment, as shown in FIG. 4, the resistance value is set based on short-time data, for example, a measurement value measured within 500 msec. These effects can be minimized because they can be calculated.

Subsequently, the switch 18 is opened to open the current measurement circuit K, an electromotive force is generated in the measurement sample S, and the resistance value is set to a value different from Re by the variable resistor 19, for example, 2Re. 18 is closed and the current measurement circuit K is connected, and the voltage drop ΔV and the current value I are measured in the same manner as described above. The resistance value in the variable resistor 19 can be appropriately set according to the thermoelectric characteristics of the measurement sample S. For example, when the measurement conditions are five, the resistance value in the variable resistor 19 can be set to 4Re, 3Re, 2Re, Re, 0 (short circuit).

By changing the resistance value in the variable resistor 19, the measured voltage drop ΔV and the current value I change. These values are in a proportional relationship, and the slope is the resistance value R of the measurement sample S. The resistance value R of the measurement sample is calculated by the following equation using the slope value when the voltage drop ΔV and the current value I are linearly approximated by the method of least squares.

The resistivity ρ is calculated from the resistance value R calculated by the above equation, the cross-sectional area A and the length L of the measurement sample by the calculation device 40 according to the following equation.

(Equation 5)
ρ = R · A / L

In the measurement using the variable resistor 19, the influence of the resistance of the current measurement circuit K can be canceled, and the error of each measurement value can be reduced by the least square method. Measurements can be made.
In addition, if the resistance value R of the measurement sample S is small, the voltage drop ΔV is very small and difficult to measure with high accuracy. However, high-precision measurement can be performed by setting an appropriate resistance value using the variable resistor 19. Can do.

(Example)
The thermoelectric property evaluation result of the thermoelectric material by the thermoelectric property evaluation apparatus 1 of the present invention was compared with the thermoelectric property evaluation result using the conventional DC four-terminal method as a comparison method.

As the measurement sample, P-type BiTe and N-type BiTe formed on a square columnar test piece having a square end face shape of 4 mm × 4 mm and a height of 6 mm were used.
As a comparison method, a direct current four-terminal method was used, the thermocouple distance was 3 mm, and the temperature difference ΔT of the end face of the measurement sample was 10 ° C.
In the measurement according to the invention, [Delta] T is set to 5 to 30 ° C., the variable resistor 19 is set to range order 10 ⁰ milliohms, were measured levels and 3 levels.

The thermoelectric property measurement result of P-type BiTe is shown in FIG. 4, and the thermoelectric property measurement result of N-type BiTe is shown in FIG. The measured values according to the present invention for both the thermoelectric power and the resistivity are in good agreement with the measured values by the comparative method, and it was confirmed that accurate measurement is possible even by the thermoelectric measurement evaluation method of the present invention.

[Effect of the embodiment]
(1) As described above, according to the thermoelectric property evaluation apparatus 1 of the present invention, 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. Is formed on the basis of the thermoelectromotive force of the measurement sample S measured by the voltmeter 16 and the temperature difference of the end surface Se of the measurement sample S measured by the thermocouples 21 and 22 with the switch 18 opened. The thermoelectric power α of the measurement sample S is calculated, and after the thermoelectromotive force of the measurement sample S is generated, the switch 18 is closed and discharged, and the voltage drop ΔV of the measurement sample S measured by the voltmeter 16 and the ammeter 17 are measured. Based on the current value I measured by the above, the resistivity ρ of the measurement sample S can be calculated.
In the measurement of the resistivity ρ, since the discharge generated in a short time by closing the switch 18 using the thermoelectromotive force of the measurement sample S is used, there is no need to use a constant current power source capable of pulse energization. Thereby, the thermoelectric characteristic evaluation apparatus 1 having a simpler configuration and lower cost than the conventional apparatus can realize highly accurate measurement of thermoelectric power and resistivity.
In addition, since the first electrode 14 and the second electrode 15 can be brought into surface contact with the end surface Se of the measurement sample S, the influence of the oxide film and the material structure non-uniformity on the measurement result can be reduced.

(2) In the measurement using the variable resistor 19, the influence of the resistance of the current measurement circuit K can be canceled, and the error of each measurement value can be reduced by the least square method. High-precision measurement can be performed.
In addition, if the resistance value R of the measurement sample S is small, the voltage drop ΔV is very small and difficult to measure with high accuracy. However, high-precision measurement can be performed by setting an appropriate resistance value using the variable resistor 19. Can do.

(3) Since the thermocouples 21 and 22 are inserted through the through holes 11c of the blocks 11a and 11b and are in contact with the end surface Se of the measurement sample S, the lengths that are difficult with the DC four-terminal method are provided. It is possible to evaluate the thermoelectric characteristics of a measurement sample having a short period.

(4) Since the blocks 11a and 11b are provided with the temperature control means 12a and 12b, respectively, the measurement sample S can be controlled to reach the measurement temperature in a short time.

[Other Embodiments]
In the above-described embodiment, the configuration including the variable resistor 19 is adopted, but the present invention is not limited to this. If the resistance of the current measurement circuit K does not significantly affect the measurement accuracy of the voltage drop ΔV and the current value I, the voltage drop ΔV and the current value I are measured without using the variable resistor 19, and the resistance value is directly measured. R may be calculated. Further, although thermocouples 21 and 22 are used as temperature measuring means, a non-contact thermometer such as a radiation thermometer can also be used using the through hole 11c.

DESCRIPTION OF SYMBOLS 1 Thermoelectric characteristic evaluation apparatus 11, 11a, 11b Block 11c Through-hole 12a Temperature control means 13 Insulating layer 14 1st electrode,
15 Second electrode 16 Voltmeter (Voltage measuring means)
17 Ammeter (Current measurement means)
18 Switch 19 Variable resistor 21, 22 Thermocouple (temperature measuring means)
30 measuring tank 40 arithmetic device (calculation means)
K current measurement circuit S measurement sample Se end face

Claims (6)

A pair of blocks configured to form a temperature difference to form a temperature gradient in the measurement sample;
A pair of first electrodes disposed between the block and an end surface of the measurement sample;
Voltage measuring means connected to the pair of first electrodes for measuring a voltage generated in the measurement sample;
A pair of second electrodes disposed between the block and an end surface of the measurement sample in a state of being insulated from the first electrode;
Current measuring means connected to the pair of second electrodes for measuring a current flowing through the measurement sample;
A switch for opening and switching a connection of a current measurement circuit comprising a measurement sample, the pair of second electrodes and the current measurement means;
A temperature measuring means for measuring the temperature near the end face of the measurement sample,
The thermoelectric power of the measurement sample is calculated based on the thermoelectromotive force of the measurement sample measured by the voltage measurement unit and the temperature difference of the end surface of the measurement sample measured by the temperature measurement unit with the switch open. After generating the thermoelectromotive force of the measurement sample, the switch is closed and discharged, and the resistance of the measurement sample is measured based on the voltage drop of the measurement sample measured by the voltage measurement means and the current value measured by the current measurement means. Computing means for calculating the rate;
The thermoelectric property evaluation apparatus according to claim 1, comprising: The thermoelectric characteristic evaluation apparatus according to claim 1, wherein the current measurement circuit includes a variable resistor having a variable resistance value. The thermoelectric property evaluation apparatus according to claim 1 or 2, wherein the temperature measuring means is provided so as to pass through the block and come into contact with an end face of a measurement sample. The thermoelectric property evaluation apparatus according to any one of claims 1 to 3, wherein the pair of blocks each incorporate temperature control means capable of temperature control. Using the thermoelectric property evaluation apparatus according to any one of claims 1 to 4,
A step of sandwiching an end face of the measurement sample between the first electrode and the second electrode and supporting the pair of blocks to form a temperature gradient on the measurement sample;
Measuring the temperature difference of the end face of the measurement sample by the temperature measuring means;
A step of measuring a thermoelectromotive force of a measurement sample by the voltage measuring means in a state where the current measuring circuit is opened by the switch; and
Calculating thermoelectric power based on the thermoelectromotive force by the computing means and the temperature difference of the end face of the measurement sample measured by the temperature measuring means;
The current measurement circuit is switched from an open state to a connected state by the switch to discharge the thermoelectromotive force of the measurement sample, and the current measurement unit measures the current value flowing through the measurement sample and the voltage measurement unit. Measuring the voltage drop by
Calculating a resistivity based on the current value and voltage drop by the computing means;
A thermoelectric property evaluation method comprising: The thermoelectric characteristic evaluation apparatus according to any one of claims 2 to 4, wherein the thermoelectric characteristic evaluation apparatus including the variable resistor is used.
A different resistance value is set in the variable resistor, a current value and a voltage drop are measured in each setting, and a resistivity is calculated based on the current value and the voltage drop corresponding to each resistance value. Item 6. The thermoelectric property evaluation method according to Item 5.

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