System and method for measuring microscopic thermal conductivity of material under loading of electric field and magnetic field

Abstract

The invention discloses a material microscopic thermal conductivity measurement system and method under electric field and magnetic field loading, and the material microscopic thermal conductivity measurement system under electric field and magnetic field loading comprises a motor fixing module, a magnetic field applying module, an electric field applying module, a sample clamping module and a thermal conductivity measurement module. Rapid loading and unloading of a magnetic field and an electric field are achieved through the magnetic field applying module and the electric field applying module, thermal conductivity information of the local scale of a material sample is directly represented through thermosensitive probes in the motor fixing module and the thermal conductivity measuring module, and the system and method are provided for research of the thermal conductivity of the sample under different magnetic fields and electric fields.

Description

Technical Field

[0001] This application belongs to the field of thermodynamics engineering, and particularly relates to a measurement system and method for the microscopic thermal conductivity of materials under the loading of electric and magnetic fields. Background Art

[0002] With the breakthrough of chip technology beyond 3 nanometers and the advancement of quantum computing towards practical applications, traditional heat dissipation technologies can no longer meet the requirements of local ultra-high heat flux and extreme temperature control. In the field of thermodynamics engineering, the thermal transport properties of materials are regulated by electric / magnetic fields to achieve tunable dynamic thermal conductivity and active programming of heat flux, thus solving the thermal management bottleneck of integrated circuits and quantum devices.

[0003] In the field of thermodynamics engineering, the thermal conductivity of multiferroic materials can be precisely regulated through the synergistic effect of electric and magnetic fields. Their non-volatile storage characteristics enable multiferroic materials to maintain the set thermal state without continuous power supply. The BiFeO3-based thermal switch material developed by the Chinese Academy of Sciences has been successfully applied to the Chang'e series of detectors, achieving a heat flux regulation efficiency of over 200% in the extreme temperature difference environment on the moon. The thin film form of multiferroic materials is perfectly compatible with existing semiconductor processes, providing an innovative solution for chip-level thermal management and showing broad application prospects in cutting-edge fields such as aerospace engineering and quantum computing.

[0004] Multiferroic materials exhibit unique advantages in the synergistic regulation of electric / magnetic fields in thermodynamics engineering, but their in-depth research still faces major technical challenges. The most prominent bottleneck in current research lies in the lack of professional equipment and technical methods for in-situ characterization at the microscopic scale, especially the difficulty in directly observing the change in local thermal conductivity and its correlation with the material structure. This lack of technology severely restricts the in-depth understanding of the thermal transport mechanism of multiferroic materials and also hinders the targeted development of new thermal functional materials. Therefore, there is an urgent need to establish a method for directly characterizing the change in local thermal conductivity of materials under the loading of electric and magnetic fields. Summary of the Invention

[0005] The purpose of this application is to provide a measurement system and method for the microscopic thermal conductivity of materials under the loading of electric and magnetic fields to achieve in-situ detection of the local microscopic magnetothermal effect of materials under magnetic fields.

[0006] According to the first aspect of the embodiments of this application, a measurement system for the microscopic thermal conductivity of materials under the loading of electric and magnetic fields is provided, which may include:

[0007] A motor fixing module for fixing the stepper motor to prevent the motor from contacting the accessory bracket of the instrument and realizing in-situ scanning tests;

[0008] A magnetic field application module for applying or unloading a magnetic field to the material sample;

[0009] An electric field application module for applying or removing an electric field to a material sample;

[0010] A sample clamping module for clamping a material sample and fixing it at a specified position;

[0011] A thermal conductivity measurement module for measuring the thermal conductivity data of a material sample at the local scale.

[0012] In some alternative embodiments of the present application, the motor fixing module includes: a motor bracket and a base;

[0013] The base is integrally formed of aluminum alloy, used to carry other components of the entire device, and is fixedly connected to the scanning platform of the atomic force microscope through screws.

[0014] There are two motor brackets, which respectively fix the torque stepping motor and the stepping motor on the base, preventing the additional bracket of the stepping motor from contacting the scanning platform of the atomic force microscope and generating friction to affect the test of the material sample, thereby realizing the in-situ scanning test of the material sample at the micron scale under the atomic force microscope.

[0015] In some alternative embodiments of the present application, the magnetic field application module includes: a permanent magnet, a silicon steel rotating shaft, a torque stepping motor, a pole shoe, and a magnetic field concentrator;

[0016] The permanent magnet is fixed on the silicon steel rotating shaft through casting glue. The silicon steel rotating shaft is connected to the rotating shaft of the torque stepping motor through a coupling. The torque stepping motor provides high torque to rotate the silicon steel rotating shaft, changing the angle between the permanent magnet on the silicon steel rotating shaft and the pole shoe, and at the same time realizing the rapid application or removal of the magnetic field according to the parameters set by the PLC and the stepping motor driver.

[0017] The pole shoe is made of silicon steel material, and the pole shoe covers the permanent magnet to reduce the magnetic field leakage in the air. When the magnetic poles at both ends of the permanent magnet rotate to the same angle as the pole shoe, the magnetic field is the largest at this time, and the magnetic field is concentrated and distributed in the high magnetic permeability pole shoe and the magnetic field concentrator, and finally forms a high magnetic field area in the magnetic field concentration area. On the contrary, the magnetic field in the magnetic field concentration area decreases.

[0018] In some alternative embodiments of the present application, the permanent magnet is a pair of radially magnetized tile-shaped neodymium iron boron magnets;

[0019] In some alternative embodiments of the present application, the electric field application module includes: a waveform generator and a high-voltage amplifier;

[0020] The waveform generator is used to generate various digital voltage wave signals required during the test;

[0021] The high-voltage amplifier is connected to the waveform generator, generates an amplified voltage signal based on the wave signal output by the waveform generator, and loads it onto the material sample.

[0022] In some alternative embodiments of the present application, the sample clamping module includes: a stepper motor, a lead screw, a reciprocating platform, and a specimen fixture;

[0023] The reciprocating platform is integrally formed by 3D printing technology and made of a high-performance resin material, which is used to isolate the applied electric field from affecting the normal operation of the device; the lead screw has left- and right-handed threads and is used to drive two reciprocating platforms in the same or opposite directions simultaneously;

[0024] The stepper motor is connected to the lead screw through a coupling, and the lead screw is connected to the two reciprocating platforms through threads;

[0025] The stepper motor drives the lead screw to rotate, thereby causing the two reciprocating platforms to move in the same or opposite directions simultaneously.

[0026] There are two specimen fixtures, and the two specimen fixtures are arranged in one-to-one correspondence with the two reciprocating platforms. Each specimen fixture is arranged on its corresponding reciprocating platform. The two specimen fixtures cooperate to clamp the material sample. The specimen fixture is 0.1 mm lower than the magnetic field application device, so that the sample is close to the magnetic field application module, reducing the influence of sample jitter during dynamic scanning.

[0027] In some alternative embodiments of the present application, the specimen fixture, the motor bracket, and the base are all made of non-magnetic material aluminum alloy, reducing the influence on the magnetic field of the magnetic field application module.

[0028] In some alternative embodiments of the present application, the sample clamping module further includes: a stepper motor control unit composed of a PLC and a motor driver;

[0029] The stepper motor control unit is used to control the rotation speed and number of steps of the stepper motor, and thus control the displacement distance and delay time of the specimen fixture.

[0030] In some alternative embodiments of the present application, the thermal conductivity measurement module includes: an atomic force microscope, a Wheatstone bridge, and a thermosensitive probe;

[0031] The atomic force microscope, the Wheatstone bridge, and the thermosensitive probe are used to in-situ detect and collect the local thermal conductivity data of the material sample.

[0032] According to the second aspect of the embodiments of the present application, a method for measuring local thermal conductivity by magnetic field and electric field regulation is provided. The method may include:

[0033] Using standard samples with different thermal conductivities to calibrate the resistance change value corresponding to the bridge voltage of the thermosensitive probe within the required test thermal conductivity range, establishing the relationship between resistance and thermal conductivity, and then fitting to obtain the resistance-thermal conductivity function;

[0034] Applying a magnetic field excitation to the material sample through the magnetic field application module;

[0035] Applying an electric field excitation to the material sample through an electric field application module;

[0036] Using a thermosensitive probe to measure the change in the local thermal conductivity of the material sample under different magnetic fields and electric fields, and converting the resistance change of the thermosensitive probe caused by the material thermal conductivity into an electrical signal through a Wheatstone bridge, which is finally collected by the thermal conductivity measurement module;

[0037] Combining with the resistance-thermal conductivity function obtained by fitting to obtain the change data of the thermal conductivity of the material sample under different magnetic fields and electric fields.

[0038] The above technical solution of the present application has the following beneficial technical effects:

[0039] The device of the embodiment of the present application realizes the rapid loading and unloading of the magnetic field and the electric field through the magnetic field application module and the electric field application module, and tests the change in the thermal conductivity of the material sample at the local scale through the thermal conductivity measurement module. Realize the direct characterization of the local thermal conductivity of the material sample under different magnetic fields and electric fields. Description of the Drawings

[0040] FIG. 1 is a schematic structural diagram of a system for measuring the microscopic thermal conductivity of a material under the loading of an electric field and a magnetic field in an exemplary embodiment of the present application;

[0041] Figure 2 is a top view schematic structural diagram of a system for measuring the microscopic thermal conductivity of a material under the loading of an electric field and a magnetic field in a specific embodiment of the present application;

[0042] Figure 3 is a schematic diagram of the magnetic field loading and unloading principle of the magnetic field application module in a specific embodiment of the present application;

[0043] Figure 4 is a flowchart of a method for measuring the microscopic thermal conductivity of a material under the loading of an electric field and a magnetic field in an exemplary embodiment of the present application;

[0044] Figure 5 is a resistance-thermal conductivity relationship diagram of the thermosensitive probe calibrated by a system for measuring the microscopic thermal conductivity of a material under the loading of an electric field and a magnetic field in a specific embodiment of the present application;

[0045] Figure 6 is a bridge voltage data diagram tested by an atomic force microscope and a thermosensitive probe control system in a specific embodiment of the present application;

[0046] Reference Signs:

[0047] 1: Atomic force microscope and thermal probe controller; 2: Coupling; 3: Base; 4: Motor bracket; 5: Torque stepping motor; 6: Magnetic field application device; 7: Stepping motor; 8: Material sample; 9: Thermal probe; 10: Device control unit; 11: Reciprocating platform and specimen fixture; 12: Coupling; 13: Lead screw; 14: Motor bracket; 15: Coupling; 16: Optical axis Detailed implementation manners

[0048] To make the objectives, technical solutions and advantages of the present application clearer and more understandable, the present application will be further described in detail below in conjunction with specific implementation manners and with reference to the accompanying drawings. It should be understood that these descriptions are only exemplary and are not intended to limit the scope of the present application. In addition, in the following descriptions, the descriptions of well-known structures and technologies are omitted to avoid unnecessarily confusing the concepts of the present application.

[0049] The schematic diagram of the layer structure according to the embodiment of the present application is shown in the accompanying drawings. These figures are not drawn to scale, and for the purpose of clarity, some details are enlarged and some details may be omitted. The shapes of various regions and layers shown in the figures, as well as their relative sizes and positional relationships, are only exemplary. In practice, there may be deviations due to manufacturing tolerances or technical limitations, and those skilled in the art can design regions / layers with different shapes, sizes, and relative positions according to actual needs.

[0050] Obviously, the described embodiments are part of the embodiments of the present application, rather than all of the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present application without creative efforts shall fall within the scope of protection of the present application.

[0051] In the description of the present application, it should be noted that the terms "first", "second", and "third" are only used for descriptive purposes and cannot be construed as indicating or implying relative importance.

[0052] In addition, the technical features involved in different implementation manners of the present application described below can be combined with each other as long as they do not conflict with each other.

[0053] The measurement system for the microscopic thermal conductivity of materials under the loading of electric and magnetic fields provided by the embodiment of the present application will be described in detail below in conjunction with the accompanying drawings, through specific embodiments and their application scenarios.

[0054] In the first aspect of the embodiment of the present application, a measurement system for the microscopic thermal conductivity of materials under the loading of electric and magnetic fields is provided, and the system may include:

[0055] A motor fixing module, configured to fix the stepping motor to prevent the motor from contacting the accessory bracket of the instrument and to realize the in-situ scanning test;

[0056] A magnetic field application module for applying or removing a magnetic field to a material sample;

[0057] An electric field application module for applying or removing an electric field to a material sample;

[0058] A sample clamping module for clamping a material sample and fixing it at a specified position;

[0059] A thermal conductivity measurement module for measuring the thermal conductivity data of a material sample at the local scale.

[0060] Through the combined use of the motor fixing module, the magnetic field application module, the electric field application module, the sample clamping module and the thermal conductivity measurement module in the above embodiments, it is possible to realize the coordinated loading or unloading of the magnetic field and the electric field on the material sample, and record and collect the data of the change in the bridge voltage of the thermal probe through the thermal conductivity measurement module, so as to measure the local thermal conductivity data of the material sample; the magnetic field application module and the electric field application module adopted can quickly generate a strong magnetic field and a high electric field in a very short time, the sample clamping module can fix the sample and make it close to the magnetic field application module, and the motor fixing module fixes the motor to realize the in-situ scanning test.

[0061] Specifically, as Figure 1-2 shown, the microscopic thermal conductivity measurement system of the material under the loading of the electric field and the magnetic field may include an atomic force microscope and a thermal probe controller 1, a coupling 2, a base 3, a motor bracket 4, a torque stepping motor 5, a magnetic field application module 6, a stepping motor 7, a material sample 8, a thermal probe 9, a device control unit 10, a reciprocating platform and a specimen fixture 11, a coupling 12, a lead screw 13, a motor bracket 14, a coupling 15, and an optical axis 16.

[0062] Among them, the atomic force microscope and the thermal probe controller 1 are used to control the movement of the thermal probe and collect the data of the voltage between the bridges caused by the change of the thermal conductivity of the sample; the coupling 2 is used to connect the stepping motor and the lead screw; the base 3 is used to install the optical axis 16 and fix the magnetic field loading module 6, the motor bracket 4, and the motor bracket 14. The base 3 is connected to the scanning platform of the atomic force microscope by screws; the motor bracket 4 is used to connect the torque stepping motor 5 and the base 3; the torque stepping motor 5 is used to apply a torque to rotate the radially magnetized permanent magnet in the magnetic field application module 6; the magnetic field application module 6 is used to apply a magnetic field to the sample; the stepping motor 7 is used to control the movement of the reciprocating platform and the specimen fixture, so that the sample is closely attached to the magnetic field application module 6; the material sample 8 is used for experimental testing; the thermal probe 9 is used to monitor the temperature change of the sample, convert the temperature change into a resistance change, and feed the data back to the Wheatstone bridge; the device control unit 10 includes a PLC, a stepping motor driver, a waveform generator, and a high-voltage amplifier, and is used to control the rotation speed and rotation angle of the torque stepping motor 5 and the stepping motor 7, and control the application and unloading of the electric field; the reciprocating platform and the specimen fixture 11 are used to cooperate to fix the sample. The reciprocating platform is insulated from the electric field and moves on the optical axis 16. The specimen fixture is conductive and is used to apply a voltage to the material sample 8; the coupling 12 is used to connect the rotating shaft of the magnetic field application module 6 and the drive shaft of the torque stepping motor 5; the lead screw 13 is used to connect the reciprocating platform 11 and drive it to move reciprocally; the motor bracket 14 is used to connect the stepping motor 7 and the base 3; the coupling 15 is used to connect the drive shaft of the stepping motor and the lead screw 13; the optical axis 16 is used to fix the reciprocating platform and the specimen fixture 11 and play the role of a guide rail;

[0063] In this embodiment, when the thermal conductivity of the material sample 8 changes due to the loading or unloading of the magnetic field and the electric field, the thermal conductivity information is sensed by the thermal probe 9 at this time, its resistance value changes simultaneously, and the resistance change information is fed back to the atomic force microscope and the thermal probe controller 1. The resistance change of the Wheatstone bridge therein is converted into a voltage change between the bridges, and finally collected by the data acquisition unit in the atomic force microscope and the thermal probe controller 1. The voltage change between the bridges is converted into the thermal conductivity change of the material sample 8 by combining the calibrated resistance-thermal conductivity function of the thermal probe 9.

[0064] In some embodiments, the motor fixing module includes: a motor bracket and a base;

[0065] The base is integrally formed of aluminum alloy material, used to carry other components of the device, and is fixedly connected to the scanning platform of the atomic force microscope by screws.

[0066] There are two motor brackets, which respectively fix the torque stepping motor and the stepping motor on the base platform, preventing the stepping motor from contacting the additional bracket of the atomic force microscope scanning platform and generating friction, which may affect the test of the material sample, so as to realize the micron-level in-situ scanning test of the material sample under the atomic force microscope.

[0067] In some embodiments, the magnetic field application module includes: a permanent magnet, a silicon steel rotating shaft, a torque stepping motor, a pole shoe, and a magnetic field concentrator;

[0068] The permanent magnet is fixed on the silicon steel rotating shaft through casting glue. The silicon steel rotating shaft is connected to the rotating shaft of the torque stepping motor through a coupling. The torque stepping motor provides high torque to rotate the silicon steel rotating shaft, changing the angle between the permanent magnet on the silicon steel rotating shaft and the pole shoe as Figure 3 shown, and at the same time, according to the parameters set by the PLC and the stepping motor driver, the magnetic field is quickly applied or unloaded.

[0069] In this embodiment, the magnetic field application module is used to provide the required magnetic field intensity during loading. The magnetic field application module emits pulses to rotate the permanent magnet through the coordinated work of the PLC and the stepping motor driver, changing the radial direction of the permanent magnet to apply or unload the magnetic field.

[0070] In some embodiments, the permanent magnet is a pair of radially magnetized tile-shaped neodymium iron boron magnets.

[0071] In some embodiments, the pole shoe is made of silicon steel material;

[0072] The pole shoe is made of silicon steel material and wraps the permanent magnet to reduce the magnetic field leakage in the air. As Figure 3 shown, when the magnetic poles at both ends of the permanent magnet rotate to the same angle as the pole shoe, the magnetic field is the largest at this time, and the magnetic field is concentrated in the high magnetic permeability pole shoe and magnetic field concentrator, and finally a high magnetic field area is formed by aggregation in the magnetic field concentration area. On the contrary, the magnetic field in the magnetic field concentration area decreases.

[0073] In some embodiments, the electric field application module includes: a waveform generator and a high-voltage amplifier;

[0074] The waveform generator is used to generate various digital voltage wave signals required during the test;

[0075] The high-voltage amplifier is connected to the waveform generator, generates an amplified voltage signal based on the wave signal output by the waveform generator, and loads the voltage onto the material sample through a wire and a specimen clamp made of metal material, while the reciprocating platform made of insulating material plays the role of isolating the electric field, avoiding the influence of the electric field on other components of the device.

[0076] In some embodiments, the sample clamping module includes: a stepping motor, a lead screw, a reciprocating platform, and a specimen clamp;

[0077] The reciprocating platform is integrally formed using 3D printing technology and is made of high-performance resin material to isolate the applied electric field from affecting the normal operation of the device; the lead screw has positive and negative threads to drive the two reciprocating platforms in opposite or opposite directions at the same time;

[0078] The stepper motor is connected to the lead screw through a coupling, and the lead screw is connected to the two reciprocating platforms through threads; the stepper motor drives the lead screw to rotate, thereby causing the two reciprocating platforms to move in opposite or opposite directions at the same time.

[0079] In this embodiment, there are two sample clamps, and the two sample clamps are arranged in a one-to-one correspondence with the two reciprocating platforms. Each sample clamp is arranged on its corresponding reciprocating platform. The two sample clamps cooperate to clamp the material sample. The sample clamp is 0.1mm lower than the magnetic field application device, so that the sample is close to the magnetic field application module, reducing the impact of sample jitter during dynamic scanning.

[0080] In some embodiments, the sample fixture, the motor bracket, and the base are all made of non-magnetic aluminum alloy. Such an arrangement can minimize interference with the direction and size of the magnetic field.

[0081] In some embodiments, the sample holding module further comprises: a stepper motor control unit;

[0082] The stepper motor control unit consists of a PLC and a stepper motor driver, which is used to control the speed and number of steps of the stepper motor, and then control the displacement distance and delay time of the sample fixture.

[0083] In some embodiments, the thermal conductivity measurement module includes: an atomic force microscope, a Wheatstone bridge, and a thermal probe;

[0084] Atomic force microscopy, Wheatstone bridge and thermal probe are used to detect and collect data on thermal conductivity changes of material samples.

[0085] In this embodiment, the atomic force microscope is the basis of the entire test system; the Wheatstone bridge is a part of the circuit in the test system, which is connected to both the atomic force microscope and the thermistor probe, and will convert the thermal signal collected by the thermistor probe into an electrical signal; the thermistor probe is used to directly collect thermal signals and convert the sensed changes in the thermal conductivity of the sample into changes in resistance.

[0086] In a second aspect of the embodiments of the present application, a method for measuring the microscopic thermal conductivity of a material under electric field and magnetic field loading is provided, such as Figure 4 As shown, the method may include:

[0087] Calibrate the resistance value of the thermistor in the thermistor probe tip within the required test thermal conductivity range and establish the relationship between thermistor resistance value and thermal conductivity, such as Figure 5 As shown, the resistance-thermal conductivity function of the thermistor is obtained;

[0088] Applying a magnetic field excitation to the sample through a magnetic field application module;

[0089] Applying an electric field excitation to the sample through an electric field application module;

[0090] Monitoring the change in the thermal conductivity of the material using a thermistor in the tip of a thermal probe;

[0091] Converting the temperature change obtained by the thermistor into a collectable bridge voltage signal through an atomic force microscope control system and a Wheatstone bridge, as Figure 6 shown, obtaining the thermal conductivity change signal of the bridge voltage with respect to factors such as different magnetic fields, electric field states, and the microstructure of the material sample;

[0092] Combining the experimentally calibrated resistance-thermal conductivity function of the thermal probe to obtain the in-situ surface scan map of the thermal conductivity of the material sample;

[0093] Specifically, it may include the following steps:

[0094] Physical field application step: Using a motor fixing module to make the sample closely adhere to the surface of the magnetic field application module; Using the magnetic field application module 6 and the electric field application module to apply magnetic field and electric field excitations to the sample;

[0095] Collection step: Using a thermal conductivity measurement module composed of an atomic force microscope controller 1, a Wheatstone bridge, and a thermal probe 9 to record and collect the thermal signals of the sample in a local area, obtaining the bridge voltage change data of the sample under different magnetic fields and electric fields;

[0096] Calibration step: Calibrating the resistance value of the thermistor in the thermal probe 9 within the required test thermal conductivity range, establishing the relationship between the thermistor resistance value and the thermal conductivity, and further obtaining the resistance-thermal conductivity function of the thermistor;

[0097] Calculation step: Combining the calibrated resistance-thermal conductivity function of the thermistor to obtain the thermal conductivity data of the sample under different magnetic fields and electric fields through conversion.

[0098] In the physical field application step, the speed of magnetic field application can be controlled by the rotational speed of the silicon steel rotating shaft controlled by a torque stepping motor 5, and the magnitude of the electric field can be controlled by the amplification factor of a voltage amplifier.

[0099] In the acquisition step, the thermal conductivity measurement module may include an atomic force microscope and a thermal probe controller 1, a thermistor probe 9, a Wheatstone bridge box, and a variable resistance box. The thermal probe 9 is controlled by the atomic force microscope and the thermal probe controller 1 to contact the material sample 8. The atomic force microscope is connected to the control module. The thermal probe 9 collects the thermal information generated by the material sample. At this time, the resistance value of the thermal probe 9 will change. Since the thermal probe 9 is in the circuit of the Wheatstone bridge, the measured resistance change signal will be converted into a signal change of the voltage between the bridges by the Wheatstone bridge and fed back to the atomic force microscope and the thermal probe controller 1, and collected by the data acquisition unit therein.

[0100] In the calculation step, in combination with the resistance-thermal conductivity function of the thermal probe 9 calibrated in the calibration step, the voltage signal between the bridges collected by the atomic force microscope and the thermal probe controller 1 is converted to obtain the thermal conductivity data at the local scale of the sample.

[0101] The above-mentioned system for measuring the microscopic thermal conductivity of materials under the loading of electric and magnetic fields in the above embodiments can measure the thermal signals in the microscopic region of the material sample while applying magnetic and electric fields separately or simultaneously, and use different physical field magnitudes and loading speeds to test the changes in the thermal conductivity of the sample during this process under different electric and magnetic field loadings, so as to study the changes in the microscopic region thermal conductivity of the sample under different magnetic and electric fields.

[0102] The embodiments of the present application have been described above in conjunction with the accompanying drawings. However, the present application is not limited to the above specific embodiments. The above specific embodiments are merely illustrative and not restrictive. Under the inspiration of the present application, those of ordinary skill in the art can also make many forms without departing from the purpose of the present application and the scope protected by the claims, and all belong to the protection scope of the present application.

Claims

1. A measurement system for the microscopic thermal conductivity of a material under the loading of an electric field and a magnetic field, characterized in that, Including: A motor fixing module for fixing the stepper motor, preventing the motor from contacting the auxiliary bracket of the atomic force microscope scanning platform, and realizing in-situ scanning test; A magnetic field applying module for applying or removing a magnetic field to the material sample; An electric field applying module for applying or removing an electric field to the material sample; A sample clamping module for clamping the material sample and fixing it at a specified position; A thermal conductivity measurement module for measuring the thermal conductivity data of the material sample at the local scale.

2. The measurement system for the microscopic thermal conductivity of a material under the loading of an electric field and a magnetic field according to claim 1, wherein The motor fixing module includes: a motor bracket and a base; The base is integrally formed of aluminum alloy material, used to carry other components of the device, and is connected and fixed to the scanning platform of the atomic force microscope through screws. There are two motor brackets, and the two motor brackets respectively fix the torque stepper motor and the stepper motor on the base, and are used to realize in-situ scanning test of the material sample at the micron level under the atomic force microscope.

3. The measurement system for the microscopic thermal conductivity of a material under the loading of an electric field and a magnetic field according to claim 1, characterized in that, The magnetic field applying module includes: a permanent magnet, a silicon steel rotating shaft, a torque stepper motor, a pole shoe and a magnetic field concentrator; The permanent magnet is fixed on the silicon steel rotating shaft through casting glue. The silicon steel rotating shaft is connected to the rotating shaft of the torque stepper motor through a coupling. The torque stepper motor quickly rotates the silicon steel rotating shaft to change the angle between the permanent magnet on the silicon steel rotating shaft and the pole shoe, so as to quickly apply or remove the magnetic field.

4. The measurement system for the microscopic thermal conductivity of a material under the loading of an electric field and a magnetic field according to claim 3, wherein The permanent magnet is a pair of radially magnetized tile-shaped neodymium iron boron magnets; The pole shoe is made of silicon steel material. The pole shoe covers the permanent magnet to reduce the magnetic field leakage in the air, so that the magnetic field is distributed in the pole shoe and the magnetic field concentrator made of soft magnetic materials as expected.

5. The measurement system for the microscopic thermal conductivity of a material under the loading of an electric field and a magnetic field according to claim 1, characterized in that, The electric field applying module includes: a waveform generator and a high-voltage amplifier; The waveform generator is used to generate the digital voltage wave signal required for the test; The high-voltage amplifier is connected to the waveform generator, and is used to generate an amplified voltage signal based on the wave signal, and is loaded onto the material sample through a wire connecting the specimen clamp.

6. The measurement system for the microscopic thermal conductivity of a material under the loading of an electric field and a magnetic field according to claim 1, characterized in that, The sample clamping module includes: a stepper motor, a lead screw, a reciprocating platform and a specimen clamp; The reciprocating platform is integrally formed by 3D printing technology and is made of high-performance resin material for insulating the electric field; the lead screw has left-hand and right-hand threads for driving the reciprocating platform to move towards or away from each other; The stepper motor is connected to the lead screw through a coupling, and the lead screw is connected to the two reciprocating platforms through left-hand and right-hand threads; the stepper motor drives the lead screw to rotate, and further makes the two reciprocating platforms move in opposite directions synchronously. There are two specimen clamps, and the two specimen clamps are arranged corresponding to the two reciprocating platforms one by one. Each specimen clamp is arranged on its corresponding reciprocating platform. The two specimen clamps cooperate to clamp the material sample. The specimen clamp is 0.1 mm lower than the magnetic field applying device, so that the sample is close to the magnetic field applying module, and the influence of sample jitter is reduced during dynamic scanning.

7. The measurement system for the microscopic thermal conductivity of a material under the loading of an electric field and a magnetic field according to claim 3, characterized in that, The specimen clamp, the motor bracket and the base are all made of non-magnetic aluminum alloy material to reduce the influence on the magnetic field of the magnetic field applying module.

8. The measurement system for the microscopic thermal conductivity of a material under the loading of an electric field and a magnetic field according to claim 5, characterized in that, The sample clamping module further includes: a stepper motor control unit composed of a PLC and a stepper motor driver; The stepper motor control unit is used to control the rotation speed and number of steps of the stepper motor, and further control the displacement distance and delay time of the specimen fixture.

9. The measurement system for the microscopic thermal conductivity of a material under the loading of an electric field and a magnetic field according to claim 1, wherein The thermal conductivity measurement module includes: an atomic force microscope, a Wheatstone bridge, and a thermosensitive probe; The atomic force microscope, the Wheatstone bridge, and the thermosensitive probe are used to in-situ measure the local thermal conductivity data of the material sample.

10. A method for measuring the microscopic thermal conductivity of a material under the loading of an electric field and a magnetic field, characterized in that, Including: By using standard samples with different thermal conductivities, calibrate the resistance change value corresponding to the bridge voltage of the thermosensitive probe within the required test thermal conductivity range, establish the relationship between resistance and thermal conductivity, and then fit to obtain the resistance-thermal conductivity function; Apply a magnetic field excitation to the material sample through the magnetic field application module; Apply an electric field excitation to the material sample through the electric field application module; Use the thermosensitive probe to test the change of the local thermal conductivity of the material sample under different magnetic fields and electric fields, and convert the resistance change of the thermosensitive probe caused by the material thermal conductivity into an electrical signal through the Wheatstone bridge, and finally collect it by the thermal conductivity measurement module; Combined with the resistance-thermal conductivity function relationship of the thermosensitive probe, obtain the local scale thermal conductivity change data of the material sample under the action of an external field, and realize the local thermal conductivity test of the material sample under different electric field and magnetic field loadings.

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