阅读说明：本技术 一种直接原位综合测量微纳材料热电性能的方法及装置 (Method and device for directly and comprehensively measuring thermoelectric performance of micro-nano material in situ ) 是由 郑兴华 杨啸 张挺 陈海生 于 2021-01-20 设计创作，主要内容包括：本发明公开了一种直接原位综合测量微纳材料热电性能的方法及装置,采用对称的双H型悬空微纳电极作为样品测量探头,消除电极与衬底间的导热热损影响；样品与电极间采用FIB或者导电导热胶固定连接,消除接触电阻与接触热阻的影响；采用样品及探头放置与高真空环境,消除空气对流热损影响；加热电极采用小功率加热、电压采用高分辨率的纳伏表或者锁相放大器等测量,消除电极因过高发热导致的辐射热损影响。可一次性针对同一个样品,精确测量样品的ZT、电导率、热导率及塞贝克系数。(The invention discloses a method and a device for directly and comprehensively measuring thermoelectric properties of a micro-nano material in situ, wherein a symmetrical double H-shaped suspended micro-nano electrode is used as a sample measuring probe to eliminate the influence of heat conduction and heat loss between the electrode and a substrate; the sample and the electrodes are fixedly connected by FIB or conductive heat-conducting adhesive, so that the influence of contact resistance and contact thermal resistance is eliminated; the sample and the probe are placed in a high vacuum environment, so that the influence of air convection heat loss is eliminated; the heating electrode is heated by adopting small power, the voltage is measured by adopting a high-resolution nano-voltmeter or a phase-locked amplifier and the like, and the influence of radiation heat loss caused by excessive heating of the electrode is eliminated. The ZT, the electric conductivity, the thermal conductivity and the Seebeck coefficient of the sample can be accurately measured by aiming at the same sample at one time.)

1. The utility model provides a direct normal position is synthesized and is measured device of receiving thermoelectric property a little material which characterized in that includes: the system comprises a measurement and control system, an industrial personal computer and a high-vacuum constant-temperature cabin, wherein the measurement and control system comprises a left electrode, a middle electrode, a right electrode, a sample, a first voltmeter, a second voltmeter, a third voltmeter, a first switch, a second switch, a first resistance box, a first power supply, a fourth voltmeter, a second power supply, a fifth voltmeter and a second resistance box;

one end of the left electrode connected with the middle electrode in parallel is connected with one pole of a first power supply, and the other end of the left electrode is connected with the first resistance box in series to the other pole of the first power supply after being connected with the middle electrode in parallel through the first switch and the second switch;

the right electrode is connected with the two poles of a second power supply after being connected with a second resistance box in series;

the left electrode, the middle electrode and the right electrode are arranged side by side at intervals, and the sample is suspended on the left electrode, the middle electrode and the right electrode;

the first voltmeter is connected in series with a branch of the left electrode of the parallel circuit of the left electrode 1 and the middle electrode; the second voltmeter is connected in parallel at two sides of the parallel circuit of the left electrode and the middle electrode; the third voltmeter is connected in parallel at two sides of the first resistance box; the fourth voltmeter is connected in parallel at two sides of the right electrode; and the fifth voltmeter is connected in parallel at two sides of the second resistance box.

2. The device for directly and comprehensively measuring the thermoelectric property of the micro-nano material in situ according to claim 1, wherein the external dimension of the sample is measured by an optical microscope or a scanning electron microscope.

3. The device for directly and comprehensively measuring the thermoelectric properties of the micro-nano material in situ according to claim 1, wherein a sample is connected to the left electrode, the middle electrode and the right electrode in a suspended manner through FIB and high-temperature conductive heat-conducting adhesive and is placed in a high-vacuum constant-temperature chamber.

4. The device for directly and comprehensively measuring the thermoelectric property of the micro-nano material in situ according to claim 1, wherein the electrode is made of a conductive material such as copper, platinum, gold or nickel.

5. The device for directly and comprehensively measuring the thermoelectric performance of the micro-nano material in situ according to claim 1, wherein the high-vacuum constant-temperature chamber comprises a mechanical pump, a molecular pump, a constant-temperature control system and a chamber body.

6. The device for directly and comprehensively measuring thermoelectric properties of micro-nano materials in situ according to claim 1, is characterized in that the width and the spacing of the electrodes are at least 100 nanometers and at most 20 micrometers, the thickness of the electrodes is at least 30 nanometers and at most 1 micrometer, and the length of the electrodes is at least 5 micrometers and at most 50 micrometers.

7. A measuring method of a device for directly and comprehensively measuring thermoelectric properties of a micro-nano material in situ according to any one of claims 1 to 6 is characterized by comprising the following steps:

(1) measuring the external dimension of the sample by an optical microscope or a scanning electron microscope;

(2) the sample is suspended and connected to the left electrode, the middle electrode and the right electrode through FIB and high-temperature conductive heat-conducting adhesive, and is placed in a high-vacuum constant-temperature chamber;

(3) firstly, the second switch is disconnected, the first switch is closed, so that the middle electrode, the left part of the sample, the left electrode, the first resistance box and the first power supply form a measuring system, the left part of the sample is used as a detector, the resistance values of the left part of the sample at different temperatures are measured, and the conductivity of the sample is obtained

(4) Then the first switch is turned off, the second switch is turned on, the middle electrode is electrified to heat the sample, heat is averagely transferred to the left electrode and the right electrode through the sample, and the temperature response of the left electrode and the right electrode is simultaneously measured through the left circuit and the right circuit, so that the temperature gradient of the right part of the sample can be obtained;

(5) the thermoelectric figure of merit, the thermal conductivity and the Seebeck coefficient of the sample can be directly obtained by combining the overall dimension of the sample, the heating power of the middle electrode and the voltage difference between the two ends of the left side of the sample, which is measured by the first voltmeter and is generated by the temperature difference.

Technical Field

The invention belongs to the field of thermoelectric materials, and particularly relates to a method and a device for directly and comprehensively measuring thermoelectric performance of a micro-nano material in situ.

Background

The thermoelectric material is a pollution-free green energy source material which directly converts heat energy and electric energy by adopting a thermoelectric effect. With the rapid development of nanotechnology, the thermoelectric material is thinned and fiberized by nanotechnology, so that the thermoelectric efficiency can be greatly improved, and the thermoelectric material can be widely applied to the medical field, the military field and the human body temperature monitoring. Thermoelectric conversion efficiency of thermoelectric materials is generally measured by thermoelectric figure of merit (ZT), but no method and device capable of directly measuring thermoelectric figure of merit exist in the world at present, ZT value is calculated by respectively measuring thermal parameters (thermal conductivity) and electrical parameters (electrical conductivity and Seekbeck coefficient) of the materials, two sample preparation and respective measurement are not only troublesome, but also wrong calculation results are often caused by different micro-nano structures of the two sample preparation.

In addition, the following problems mainly exist in the aspect of material thermoelectric property measurement: 1. most of the existing measuring instruments are macroscopic materials, most of the existing measuring instruments are import equipment, and few instruments are independently developed in China. The existing instrument has no effect on micro-nano low-dimensional materials, and is lack of a reliable and convenient micro-nano low-dimensional material thermoelectric performance measuring instrument. 2. The existing measuring instrument and method are respectively designed for electricity and heat, so that ZT cannot be directly measured, and the heat/electricity performance of the material cannot be simultaneously represented. 3. The difficulties for direct in-situ characterization of the thermoelectric performance of the micro-nano material include how to ensure that an electric signal and a thermal signal do not interfere with each other, how to realize high-precision measurement of the thermal signal and the electric signal, how to directly and accurately measure thermal performance and electrical performance parameters of the same sample in situ, and how to directly and independently obtain the thermal performance and the electrical performance parameters of the same sample without dependence among the parameters.

Disclosure of Invention

In order to solve the problem that the prior art cannot accurately measure the thermoelectric figure of merit, the invention provides a method and a device for directly and comprehensively measuring the thermoelectric performance of a micro-nano material in situ, which can directly and accurately measure ZT, thermal conductivity, electric conductivity and Seebeck coefficient of a sample in situ at one time aiming at the same micro-nano sample (film or fiber).

The invention relates to a device for directly and comprehensively measuring thermoelectric performance of a micro-nano material in situ, which comprises the following components: the system comprises a measurement and control system, an industrial personal computer and a high-vacuum constant-temperature cabin, wherein the measurement and control system comprises a left electrode, a middle electrode, a right electrode, a sample, a first voltmeter, a second voltmeter, a third voltmeter, a first switch, a second switch, a first resistance box, a first power supply, a fourth voltmeter, a second power supply, a fifth voltmeter and a second resistance box 15;

one end of the left electrode connected with the middle electrode in parallel is connected with one pole of a first power supply, and the other end of the left electrode is connected with the first resistance box in series to the other pole of the first power supply after being connected with the middle electrode in parallel through a first switch and a second switch;

the right electrode is connected with the two poles of a second power supply after being connected with a second resistance box in series;

the left electrode, the middle electrode and the right electrode are arranged side by side at intervals, and the sample is suspended on the left electrode, the middle electrode and the right electrode;

the first voltmeter is connected in series with a branch of the left electrode of the parallel circuit of the left electrode 1 and the middle electrode; the second voltmeter is connected in parallel at two sides of the parallel circuit of the left electrode and the middle electrode; the third voltmeter is connected in parallel at two sides of the first resistance box; the fourth voltage meter is connected in parallel on two sides of the right electrode; and the fifth voltmeter is connected in parallel at two sides of the second resistance box.

Further, the external dimensions of the sample are measured by an optical microscope or a scanning electron microscope.

Furthermore, the sample is connected to the left electrode, the middle electrode and the right electrode in a suspension manner through FIB and high-temperature conductive heat-conducting adhesive, and is placed into a high-vacuum constant-temperature cabin.

Furthermore, the high-vacuum constant-temperature chamber is composed of a mechanical pump, a molecular pump, a constant-temperature control system and a chamber body.

Further, the electrodes are made of conductive materials such as copper, platinum, gold or nickel.

Further, the width and the interval of the electrodes are minimum 100 nanometers and maximum 20 micrometers, and the thickness of the electrodes is minimum 30 nanometers and maximum 1 micrometer. The electrode length is a minimum of 5 microns and a maximum of 50 microns.

Further, the industrial personal computer comprises a data acquisition system.

A method for directly and comprehensively measuring thermoelectric performance of a micro-nano material in situ comprises the following steps:

(1) measuring the external dimension of the sample by an optical microscope or a scanning electron microscope;

(2) the sample is suspended and connected to the left electrode, the middle electrode and the right electrode through FIB and high-temperature conductive heat-conducting adhesive, and is placed in a high-vacuum constant-temperature chamber;

(3) firstly, the second switch is disconnected, the first switch is closed, so that the middle electrode, the left part of the sample, the left electrode, the first resistance box and the first power supply form a measuring system, the left part of the sample is used as a detector, the resistance values of the left part of the sample at different temperatures are measured, and the conductivity of the sample is obtained

(4) Then the first switch is switched off, the second switch is switched on, the middle electrode is electrified to heat the sample, and the heat is averagely transferred to the left electrode and the right electrode through the sample. The temperature response of the left electrode and the right electrode is measured simultaneously through the left circuit and the right circuit, and the temperature gradient of the right part of the sample can be obtained;

(5) the thermoelectric figure of merit, the thermal conductivity and the Seebeck coefficient of the sample can be directly obtained by combining the overall dimension of the sample, the heating power of the middle electrode and the voltage difference between the two ends of the left side of the sample, which is measured by the first voltmeter and is generated by the temperature difference.

According to the method and the device for directly and comprehensively measuring the thermoelectric performance of the micro-nano material in situ, the symmetrical double H-shaped suspended micro-nano electrodes are used as sample measuring probes, so that the influence of heat conduction and heat loss between the electrodes and the substrate is eliminated; the sample and the electrodes are fixedly connected by FIB or conductive thermal conductive adhesive, so that the influence of contact resistance and contact thermal resistance is eliminated; the sample and the probe are placed in a high vacuum environment, so that the influence of air convection heat loss is eliminated; the heating electrode is heated by low power, and the voltage is measured by a high-resolution nano-voltmeter or a phase-locked amplifier, so that the influence of radiation heat loss caused by excessive heating of the electrode is eliminated. The ZT, the electric conductivity, the thermal conductivity and the Seebeck coefficient of the sample can be accurately measured aiming at the same sample at one time.

Drawings

FIG. 1 is a schematic diagram of a measuring method and a device for directly and comprehensively measuring the thermoelectric performance of a micro-nano material in situ.

FIG. 2 is a schematic diagram of a measurement and control system for directly and comprehensively measuring the thermoelectric property of the micro-nano material in situ.

Detailed Description

In order that the invention may be better understood, the following further description is provided, taken in conjunction with the accompanying examples, so that the advantages and features of the invention will be better understood by those skilled in the art. It should be noted that the following description is only a preferred embodiment of the present invention, but the present invention is not limited to the following embodiment. In fact, it will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the scope or spirit of the invention. For instance, features illustrated or described as part of one embodiment, can be used with another embodiment to yield a still further embodiment. Therefore, it is intended that the present invention encompass such modifications and variations within the scope of the appended claims and their equivalents.

The invention relates to a device for directly and comprehensively measuring thermoelectric performance of a micro-nano material in situ, which comprises the following components: the system comprises a measurement and control system A, an industrial personal computer B and a high-vacuum constant-temperature cabin C, wherein the measurement and control system comprises a left electrode 1, a middle electrode 2, a right electrode 3, a sample 4, a first voltmeter 5, a second voltmeter 6, a third voltmeter 7, a first switch 8, a second switch 9, a first resistance box 10, a first power supply 11, a fourth voltmeter 12, a second power supply 13, a fifth voltmeter 14 and a second resistance box 15;

one end of the left electrode 1 connected with the middle electrode 2 in parallel is connected with one pole of a first power supply 11, and the other end of the left electrode 1 is connected with a first resistance box 10 in series after being connected with the middle electrode 2 in parallel through a first switch 8 and a second switch 9;

the right electrode 3 is connected with the two poles of the second power supply 13 after being connected with the second resistance box 15 in series;

the left electrode 1, the middle electrode 2 and the right electrode 3 are arranged side by side at intervals, and the sample 4 is suspended on the left electrode 1, the middle electrode 2 and the right electrode 3;

the first voltmeter 5 is connected in series with a branch of the left electrode 1 of the parallel circuit of the left electrode 1 and the middle electrode 2; the second voltmeter 6 is connected in parallel at two sides of the parallel circuit of the left electrode 1 and the middle electrode 2; the third voltmeter 7 is connected in parallel at two sides of the first resistance box 10; the fourth voltmeter 12 is connected in parallel at two sides of the right electrode 3; the fifth voltmeter 14 is connected in parallel to both sides of the second resistance box 15.

Further, the outer dimensions of the sample 3 are measured by an optical microscope or a scanning electron microscope.

Further, the sample 4 is connected to the left electrode 1, the middle electrode 2 and the right electrode 3 in a suspension manner through FIB and high-temperature conductive heat-conducting adhesive, and is placed into the high-vacuum constant-temperature chamber C.

Furthermore, the high-vacuum constant-temperature cabin C is composed of a mechanical pump, a molecular pump, a constant-temperature control system and a cabin body.

Further, the electrodes are made of conductive materials such as copper, platinum, gold or nickel.

Further, the width and the interval of the electrodes are minimum 100 nanometers and maximum 20 micrometers, and the thickness of the electrodes is minimum 30 nanometers and maximum 1 micrometer. The electrode length is a minimum of 5 microns and a maximum of 50 microns.

Further, the industrial personal computer comprises a data acquisition system.

A measuring method of a device for directly and comprehensively measuring thermoelectric properties of micro-nano materials in situ comprises the following steps:

(1) measuring the external dimension of the sample 4 by an optical microscope or a scanning electron microscope;

(2) the sample 4 is connected to the left electrode 1, the middle electrode 2 and the right electrode 3 in a suspending way through FIB and high-temperature conductive heat-conducting adhesive, and is placed in a high-vacuum constant-temperature cabin C;

(3) firstly, the switch 9 is opened, the switch 8 is closed, so that the middle electrode 2, the left part of the sample 4, the left electrode 1, the resistance box 10 and the left power supply 11 form a measuring system, the left part of the sample 4 is used as a detector, the resistance values of the left part of the sample 4 at different temperatures are measured, and the conductivity of the sample is obtained

(4) Then, the switch 8 is opened and the switch 9 is closed as shown in fig. 1, the middle electrode 2 is electrified to heat the sample 4, and the heat is averagely transferred to the left and right electrodes 1 and 3 through the sample 4. The temperature gradient of the right part of the sample 4 can be obtained by simultaneously measuring the temperature response of the electrodes 2 and 3 through a left circuit and a right circuit;

(5) the thermoelectric figure of merit, thermal conductivity and seebeck coefficient of the sample can be directly obtained by combining the overall dimension of the sample and the heating power of the middle electrode 2 and the voltage difference generated by the temperature difference (due to the symmetrical structure, the temperature difference is the same as the right side of the sample) at the two ends of the left side of the sample 4 measured by the first voltmeter 5.

Further, the voltmeter is a high-precision nano-volt meter.

The thermoelectric parameters of the material are defined as follows:

wherein S is a Seekbeck coefficient, sigma is material electrical conductivity, rho is material electrical resistivity, kappa is material thermal conductivity, DeltaU is material two-end voltage, DeltaT is material two-end temperature difference, T is absolute temperature, R is material resistance value, and P is electric heating power of the thermal electrode.

According to the parameter definition, the direct in-situ comprehensive characterization of the thermoelectric property of the micro-nano material is carried out by adopting the principle shown in the following figure 1. The length and width dimensions of the appearance of the sample are measured by an optical microscope or a scanning electron microscope. The micro-nano measurement module consists of three suspended micro-nano electrodes. A sample is connected with the three electrodes (eliminating contact thermal resistance and resistance) through FIB and high-temperature conductive heat-conducting adhesive and then is placed in a high-vacuum constant-temperature chamber, so that the influence of air convection heat loss on electrode temperature measurement is eliminated, and meanwhile, measurement in a wide temperature range is realized. Firstly, the switch 9 is opened, the switch 8 is closed, so that the middle electrode 2, the left part of the sample 4, the left electrode 1, the resistance box 10 and the left power supply 11 form a measuring system, the left part of the sample 4 is used as a detector, and the resistance values of the left part of the sample 4 at different temperatures are measured, so that the conductivity of the sample is obtained. Then, the switch 8 is opened and the switch 9 is closed as shown in fig. 1, the middle electrode 2 is electrified to heat the sample 4, and the heat is evenly transferred to the left and right electrodes 1 and 3 through the sample 4. The temperature gradient of the right part of the sample 4 can be obtained by simultaneously measuring the temperature response of the electrodes 2 and 3 through a left circuit and a right circuit (because of the symmetrical structure, the heat flows of the left side and the right side of the sample 4 are the same, the temperature rise of the electrodes 1 and 3 is also the same, and the temperature gradient of the left side and the right side of the sample 4 is also the same). In the whole measuring process, the sample and the electrodes are of micro-nano structures, so that the heating power is low, the temperature rise of the three suspended electrodes is low, and the influence of radiant heat loss is eliminated. The thermoelectric figure of merit, the thermal conductivity and the Seebeck coefficient of the sample can be directly obtained by combining the overall dimension of the sample, the heating power of the middle electrode 2 and the voltage difference generated by the temperature difference at the two ends (the same as the right side of the sample 4) at the left side of the sample 4 measured by the high-precision nano-volt meter 5, and all the parameters are not in a supporting relation with each other. Therefore, the thermal conductivity and the electrical parameter of the thermoelectric figure of merit do not need to be measured by different measuring systems when the thermoelectric figure of merit is measured. And each parameter can be simultaneously represented in one measurement without moving the sample, so that the measurement error caused by multiple times of installation of the sample is eliminated, even the ZT calculation error caused by the difference of the two samples is avoided, and the measurement precision and the measurement efficiency are higher.

The measuring principle structure is shown in fig. 1, and the electrodes 1, 2 and 3 are separated from the substrate through micromachining to be suspended so as to eliminate the influence of substrate heat conduction on the measuring process. The electrode material can be a metal material with large resistance temperature coefficient and good resistance temperature linearity, such as platinum, gold or nickel. The electrode width and electrode spacing were minimum 1 micron, maximum 20 microns, electrode thickness was minimum 30 nm, maximum 1 micron depending on sample size. The electrode length is 5 microns minimum and 50 microns maximum. The sample is laid on the three suspended electrodes and is connected with the electrodes through FIB or conductive adhesive, so that the influence of contact thermal resistance and contact resistance is eliminated. The sample and the electrode are placed in a high vacuum chamber together, the influence of air convection is eliminated, and meanwhile, constant temperature environments (-196-1000 ℃) with different temperatures are provided. The power supplies 11 and 13 provide excitation current for the measurement system, which may be either a dc or ac source. The voltage meter 5/6/7/12/14 is used to measure the voltage signal at different locations, and depending on the power type, the voltage meter may be a high precision nano-volt meter or a lock-in amplifier. The resistance values of different parts can be obtained by combining the high-precision adjustable resistance boxes (or program control resistors) 10 and 15.

According to the method and the device for directly and comprehensively measuring the thermoelectric performance of the micro-nano material in situ, the symmetrical double H-shaped suspended micro-nano electrodes are used as sample measuring probes, so that the influence of heat conduction and heat loss between the electrodes and the substrate is eliminated; the sample and the electrodes are fixedly connected by FIB or conductive thermal conductive adhesive, so that the influence of contact resistance and contact thermal resistance is eliminated; the sample and the probe are placed in a high vacuum environment, so that the influence of air convection heat loss is eliminated; the heating electrode is heated by low power, and the voltage is measured by a high-resolution nano-voltmeter or a phase-locked amplifier, so that the influence of radiation heat loss caused by excessive heating of the electrode is eliminated. The ZT, the electric conductivity, the thermal conductivity and the Seebeck coefficient of the sample can be accurately measured aiming at the same sample at one time.

The foregoing description of the embodiments is presented to enable one of ordinary skill in the art to make and use the invention and is not intended to limit the invention to the particular forms disclosed. It will be readily apparent to those skilled in the art that various modifications to these embodiments may be made, and the generic principles described herein may be applied to other embodiments without the use of the inventive faculty. Therefore, those skilled in the art should, in light of the present disclosure, appreciate that many changes and modifications can be made in the invention without departing from the scope of the invention.