CN-121740950-B - Vacuum variable-temperature Seebeck coefficient measuring device based on sample scanning

CN121740950BCN 121740950 BCN121740950 BCN 121740950BCN-121740950-B

Abstract

The invention provides a vacuum variable-temperature Seebeck coefficient measuring device based on sample scanning, which comprises a vacuum cavity, a probe assembly, a sample assembly and a data acquisition and processing system, wherein the probe assembly comprises a fixed temperature control probe, a first thermocouple and a first temperature control unit, and the sample assembly comprises a temperature control sample base, a sample table, a second thermocouple and a second temperature control unit and is driven by a low-temperature piezoelectric displacement table to perform two-dimensional scanning motion relative to the probe. The first temperature control unit and the second temperature control unit are mutually independent and respectively control the temperature of the probe and the sample base so as to form a stable temperature gradient at a contact point, and the data acquisition and processing system acquires thermoelectric voltage and temperature signals under the temperature gradient and calculates a micro-area Seebeck coefficient. The device breaks through the limitation that the existing equipment can only work at room temperature, realizes the high-precision and high-resolution scanning test of the material micro-area Seebeck coefficient under the vacuum low-temperature environment, and provides a novel technical means for the study of low-temperature thermoelectric materials.

Inventors

LI GUODONG
LU TIANBO
ZHANG ZHENG
LIANG WENJIE

Assignees

中国科学院物理研究所

Dates

Publication Date: 20260508
Application Date: 20260213

Claims (10)

1. Vacuum alternating temperature Seebeck coefficient measuring device based on sample scanning, characterized by that, it includes: A vacuum chamber (20) for providing a vacuum environment required for testing; the probe assembly comprises a temperature control probe (7), a first thermocouple for measuring the temperature of the probe and a first temperature control unit for controlling the temperature of the probe, wherein the probe assembly is fixedly arranged in the vacuum cavity (20); A sample assembly comprising a temperature controlled sample mount (16), a sample stage for mounting a sample (26), a second thermocouple for measuring the temperature of the sample (26), and a second temperature control unit for controlling the temperature of the sample (26), the sample assembly being mounted within the vacuum chamber (20) by a low temperature piezoelectric displacement stage (18), the low temperature piezoelectric displacement stage (18) being configured to drive the sample assembly in a planar two-dimensional motion relative to the fixed probe assembly to effect a scanning test; The temperature control system comprises a temperature control probe (7) and a temperature control sample base (16), wherein the temperature control probe (7) and the temperature control sample base (16) are mutually independent, so that a stable temperature gradient is formed at the contact point of the temperature control probe (7) and the sample (26), the temperature control probe and the temperature control sample base (26) comprise a refrigerating module and a heating module, the refrigerating module respectively connects a cold head of a Stirling refrigerator (33) with the temperature control probe (7) and the temperature control sample base (16) through a first flexible heat conductor (23) and a second flexible heat conductor (13) to realize the refrigeration of the probe and the sample base, and the heating module is a first heating sheet (2) and a second heating sheet (27) which are respectively attached to the temperature control probe (7) and the temperature control sample base (16) to perform compensation heating, and the refrigerating module and the heating module are combined to independently and precisely control the temperature of the probe and the sample base; And the data acquisition and processing system is used for acquiring a thermoelectric signal and a temperature signal generated by the sample (26) under the temperature gradient and calculating a Seebeck coefficient of a micro-area of the sample (26).
2. The vacuum temperature swing Seebeck coefficient measuring device according to claim 1, wherein the first temperature control unit and the second temperature control unit further comprise: The temperature measuring module is a first temperature sensor (1) and a second temperature sensor (25) which are respectively attached to the temperature control probe (7) and the temperature control sample base (16); The temperature controller (30) receives signals of the first temperature sensor (1) and the second temperature sensor (25), and drives the first heating plate (2) and the second heating plate (27) to work by adopting a PID control algorithm, so that accurate control of temperature is realized.
3. The vacuum temperature swing Seebeck coefficient measurement device of claim 2, wherein the device comprises a thermal management configuration that establishes and maintains a stable local temperature field, comprising: a. A basic thermal insulation, the vacuum cavity (20) is connected with a vacuum pump set (34) and is configured to maintain a vacuum degree of not higher than 10 -3 Pa so as to eliminate gas convection heat transfer and prevent frosting in the cavity at low temperature; b. The active temperature control design is that a refrigeration module in the first temperature control unit and the second temperature control unit respectively connects a cold head of a Stirling refrigerator (33) with the temperature control probe (7) and the temperature control sample base (16) through a first flexible heat conductor (23) and a second flexible heat conductor (13) so as to realize the refrigeration of the probe and the sample base, and the first heating sheet (2) and the second heating sheet (27) are combined for compensating and heating to independently and accurately control the temperature of the probe and the sample base; c. thermal control and isolation of the connection, comprising: c1. the temperature control probe (7) is connected through a pressure sensor (3), and the pressure sensor (3) is installed in the vacuum cavity (20) through an L-shaped fixing bracket (4) comprising a heat insulation gasket (5) so as to inhibit heat leakage from the temperature control probe (7) to the bracket through a fixing structure of the temperature control probe; c2. The insulating heat conduction of the sample assembly is that the sample support (10) for installing the sample (26) and the temperature control sample base (16) are connected by an insulating heat conducting sheet (11) and a low-temperature adhesive so as to realize heat conduction and electric insulation between the sample support and the temperature control sample base; c3. the temperature of the thermocouple reference end is stable, namely the non-temperature measuring ends of the first thermocouple (8) and the second thermocouple (9) are welded on the copper-clad AlN substrate (12) fixed on the temperature control sample base (16) together, so that the reference ends of the two thermocouples are at the same and stable temperature.
4. The vacuum temperature-changing Seebeck coefficient measuring device according to claim 2, wherein the first heating plate (2) and the second heating plate (27) are ceramic heating plates, the first temperature sensor (1) and the second temperature sensor (25) are Pt100 thermometers, and the temperature controller (30) is a dual-channel temperature controller.
5. The vacuum temperature-varying Seebeck coefficient measuring device according to claim 1, wherein the low-temperature piezoelectric displacement stage (18) is driven by a piezoelectric ceramic material by using an inverse piezoelectric effect of the piezoelectric ceramic, and the displacement accuracy thereof is in the order of micrometers or submicron.
6. The vacuum temperature varying Seebeck coefficient measuring device according to claim 1, wherein the probe assembly further comprises a pressure sensor (3), the pressure sensor (3) being connected to the temperature control probe (7) for monitoring and controlling in real time the contact force between the temperature control probe (7) and the sample (26).
7. The vacuum temperature swing Seebeck coefficient measurement device according to claim 1, wherein the data acquisition and processing system comprises a nanovoltmeter (28) and a multichannel matrix switch (29); The input end of the multichannel matrix switch (29) is connected to a plurality of voltage test points, the output end of the multichannel matrix switch (29) is connected to the input channels of the nano-voltmeter (28), and a single nano-voltmeter (28) sequentially or selectively collects multiple voltage signals by switching the channels of the multichannel matrix switch (29).
8. The vacuum temperature swing Seebeck coefficient measurement device according to claim 1, wherein the sample stage comprises a sample holder (10), the sample (26) being secured within the sample holder (10) by a wood alloy (24); Wherein, an insulating heat conducting sheet (11) is arranged between the sample holder (10) and the temperature control sample base (16) to realize electric insulation and heat conduction.
9. The vacuum temperature varying Seebeck coefficient measuring device according to claim 1, wherein the sample assembly further comprises a copper-clad AlN substrate (12) fixed on the temperature controlling sample base (16), wherein non-temperature measuring ends of the first thermocouple (8) and the second thermocouple (9) are welded on the copper-clad AlN substrate (12), and wires for extracting a voltage test signal are welded on the copper-clad AlN substrate (12).
10. The vacuum temperature swing Seebeck coefficient measurement device of claim 1, wherein the device is configured to perform a two-dimensional scan test on the Seebeck coefficient of a sample at any temperature point between 100-300K with a measurement error of less than 10%.

Description

Vacuum variable-temperature Seebeck coefficient measuring device based on sample scanning Technical Field The invention belongs to the field of thermoelectric material performance test, and particularly relates to a vacuum variable-temperature Seebeck coefficient measuring device based on sample scanning. Background Thermoelectric technology has been widely used in many fields as a new energy technology for converting electric energy and thermal energy into each other. The performance of a thermoelectric device is primarily dependent on the performance of the thermoelectric material used therein, which is generally characterized by a dimensionless figure of merit zT expressed as: Wherein S is the Seebeck coefficient of the material, sigma is the conductivity, For thermal conductivity, T is absolute temperature. The Seebeck coefficient is a physical quantity reflecting the potential difference generating capability of a material under the action of a temperature gradient, is defined as s=dv/dT, and characterizes the diffusion behavior of carriers (electrons or holes) under the action of the temperature gradient, and directly influences the energy conversion efficiency of the thermoelectric material. Therefore, the Seebeck coefficient of the thermoelectric material is accurately and efficiently tested, and the method has great significance for evaluating the performance of the thermoelectric device. Currently, there are various commercial instruments for measuring Seebeck coefficient of materials, such as ZEM-3 manufactured by ULVAC-RIKO, LSR-3 manufactured by LINSEIS, germany, CTA-3 manufactured by Ke Rui European technology Co.Ltd. The instruments are based on a static method, a temperature gradient is established by arranging heating plates and cooling plates at two ends of a sample, and a thermocouple probe is used for measuring the temperature difference and the potential difference between two points, so that the Seebeck coefficient is calculated. However, the static method requires a series of small temperature differences and corresponding potential differences to be measured point by point, and the overall measurement speed is slow. Patent CN102967624B discloses a Seebeck coefficient measuring device using a quasi-static method, which can rapidly measure a Seebeck coefficient of a sample in a certain temperature range and obtain a large number of data points, so as to accurately reflect the variation trend and peak value of the Seebeck coefficient. However, the method is only suitable for measuring the macro scale (millimeter magnitude), the average Seebeck coefficient in the measuring area is obtained, and the Seebeck coefficient measurement on the micro-area scale can not be realized. For micro-region Seebeck coefficient measurement, patent CN104614557B proposes a measurement device and method based on atomic force microscopy. In addition, there are studies on micro-segment Seebeck coefficient measurement by scanning tunnel microscopy or scanning thermal microscopy, but these methods are generally complicated to operate, expensive in equipment, and high in test cost. A commercial device, a conductivity-Seebeck coefficient scanning probe microscope (Potential-Seebeck Microprobe, PSM), is developed by Germany PANCO company in combination with the Germany aerospace center, and can realize the two-dimensional distribution accurate measurement of the Seebeck coefficient. The equipment structure is shown in figure 1, and mainly comprises a P1-three-vector axis positioning platform and a controller thereof, a P2-base, a P3-sample stage, a sample clamp, a P4-probe, a P5-heating ceramic tube, a P6-conductive copper block for clamping a sample, a P7-sample and P8-two T-shaped thermocouples. The device measures temperature T 1 by moving a heating probe to the surface of the sample, using a thermocouple to which the probe is attached, the sample is held in good electrothermal contact with the copper block and temperature T 0 is measured by another thermocouple. The probe tip forms a temperature gradient at the local part of the sample, and the Cu-Cu and CuNi-CuNi wires of the thermocouple are combined to measure voltages U 0 and U 1, so that a Seebeck coefficient S s is obtained through calculation according to formulas (1.1) to (1.3). However, the device is large in size, and can only perform Seebeck coefficient scanning test under room temperature conditions in an atmospheric environment, so that temperature-changing scanning measurement cannot be realized in a low-temperature environment. This has significant limitations for intensive studies of the material's local thermoelectric properties. Many low temperature thermoelectric materials need to exhibit significant Seebeck coefficient differences under specific low temperature conditions, and their intrinsic properties also tend to be fully exhibited in low temperature environments. Therefore, the device for realizing Seebeck coefficient scanning test under