System and method for measuring electrostrictive strain of ferroelectric material under variable temperature and variable load conditions

Abstract

The invention discloses a system and a method for measuring the electrostrictive strain of a ferroelectric material under variable temperature and variable load conditions. The system comprises a thermal field generation unit, a test signal generation unit, a strain measurement unit and an equipment control and data analysis unit. The method comprises the following steps: setting a temperature through a thermal field generation unit and changing the temperature according to a test requirement; adjustable voltage excitation is generated through the test signal generation unit; the strain measurement unit is used for measuring the output micro mechanical displacement of the to-be-measured sample generated by the electrostrictive strain effect under the real force load condition; and the equipment control and data analysis unit is used for generating an electrostrictive strain loop and a real-time strain curve. The device is suitable for ferroelectric samples in various forms, high-stability and high-sensitivity electrostrictive strain testing can be achieved in complex thermal field and force field environments, and a stable electrostrictive strain loop and a real-time strain curve can be generated.

Description

Technical Field

[0001] This invention belongs to the field of ferroelectric materials, and specifically relates to a system and method for measuring the electroinduced strain of ferroelectric materials under varying temperature and load conditions. Background Technology

[0002] Ferroelectric materials are a class of smart materials with spontaneous polarization properties. An applied electric field can rearrange their internal polarization structure, resulting in macroscopic deformation and strain output that changes with the electric field strength. This characteristic makes ferroelectric materials core materials for actuators and signal converters. In recent years, ferroelectric materials have been widely used in key fields such as national defense, information and communication, and healthcare due to their large mechanical response driven by electric fields, low power consumption, and excellent miniaturization and integration potential. Electrostrain curves reflect the overall deformation capability of ferroelectric materials driven by electric fields. They contain several key parameters for evaluating micro / nano-driven and force-to-electric signal conversion performance, such as maximum strain, energy loss, and operational stability in external fields. Analyzing these characteristic parameters can further reveal the domain wall movement, phase transition mechanism, and nonlinear response characteristics of the materials, thereby deepening the understanding of the relationship between their microstructure and macroscopic performance and helping to evaluate the actual operational performance of corresponding force-to-electric functional devices.

[0003] Currently, the performance of advanced ferroelectric materials is often highly sensitive to temperature. Their polarization intensity, phase transition characteristics, and nonlinear response all change significantly with temperature, thus the shape of the electrostrain loop also changes markedly. Therefore, accurately measuring the electrostrain signal of ferroelectric materials, especially the electrostrain signal under real force load, during continuous changes in temperature and electric field strength (i.e., under varying temperature and electric field strength conditions) is of great significance for evaluating the service performance of ferroelectric materials under actual operating conditions.

[0004] Although various electrostrain testing methods exist, including optical measurement methods (such as laser interferometry), displacement sensor methods (such as LVDT and strain gauges), and scanning probe technology, these traditional methods have many shortcomings in practical applications. For example, optical methods, represented by laser interferometry, have high requirements for the testing environment, poor anti-interference capabilities, and are difficult to test under real force load conditions; while displacement sensor methods are contact measurements, which are prone to introducing uncontrollable mechanical resistance or spurious signals. Therefore, there is an urgent need to develop a novel electrostrain signal testing system and method that can simulate actual working conditions (variable temperature conditions, electric field strength, and load force field changes).

[0005] The information disclosed in the background section is only intended to enhance the understanding of the background of the present invention, and therefore may contain information that does not constitute prior art known to those skilled in the art. Summary of the Invention

[0006] To address the shortcomings of existing technologies, this invention proposes a system for measuring the electrostrain of ferroelectric materials under varying temperature and load conditions. The system comprises:

[0007] Thermal field generating unit, movable variable load upper electrode and laser vibration meter;

[0008] The system uses a thermal field generating unit to control the temperature of the sample to be tested. The thermal field generating unit is used to set the temperature and can adjust the temperature according to the test requirements.

[0009] The system uses a movable variable load upper electrode to apply a variable electric field strength and force load to the sample under test. The small mechanical displacement of the sample under test caused by the electro-strain effect is transmitted through the movement of the movable variable load upper electrode during the test. At the same time, the operating temperature of the laser vibrometer can be kept away from the influence of the thermal field generating unit. The force load is adjusted by different configurations of the counterweights of the movable variable load upper electrode.

[0010] The system uses a laser vibrometer to focus a laser beam onto the upper surface of a movable variable load electrode, and measures the real-time displacement signal of the movable variable load electrode non-contactly via an insulating reflective film set on the electrode, so as to obtain the electro-strain signal of the sample under varying temperature and load conditions.

[0011] Preferably, the system further includes a test signal generation and amplification unit, which is used to apply adjustable DC and AC voltage excitation to the sample under test according to the test requirements.

[0012] Preferably, the system further includes: an equipment control and data analysis unit, used to process the data corresponding to the signal after the signal is converted from analog to digital and to generate an electro-induced strain loop and a real-time strain curve.

[0013] Preferably, the upper surface of the movable variable load upper electrode is provided with an insulating reflective film, which is used not only for insulation protection, but also for receiving and reflecting the laser from the laser vibrometer.

[0014] Preferably, the movable variable load upper electrode further includes a copper electrode; the lower end of the copper electrode is a spherical pressure head, which is used to conduct electricity while increasing the contact area with the sample by applying a load.

[0015] Preferably, the movable variable load upper electrode further includes: a counterweight; by changing the specifications and quantity of the counterweight, the force load applied to the sample to be tested can be changed.

[0016] This invention also discloses a method for measuring the electrostrain of ferroelectric materials under varying temperature and load conditions, the method comprising:

[0017] A method for measuring the electrostrain of ferroelectric materials under varying temperature and load conditions, characterized in that the method comprises:

[0018] It can set the temperature and make the temperature change according to the test requirements to control the temperature of the sample to be tested;

[0019] A movable variable load upper electrode is used to apply a variable electric field strength and force load to the sample under test. The small mechanical displacement of the sample under test caused by electrostrain is transmitted through the movement of the movable variable load upper electrode during the test. At the same time, the operating temperature of the laser vibrometer can be kept away from the influence of the thermal field generating unit. The force load is adjusted by different configurations of the counterweights of the movable variable load upper electrode.

[0020] A laser vibrometer is used to focus a laser beam onto the upper surface of a movable variable load electrode. The real-time displacement signal of the movable variable load electrode is measured non-contactly via an insulating reflective film on the electrode, thereby obtaining the displacement signal caused by the electrostrain of the sample under test.

[0021] Preferably, the method further includes: processing the data corresponding to the signal after analog-to-digital conversion and generating electro-strain loops and real-time strain curves under varying temperature and load conditions. The present invention also discloses a computer storage medium, wherein the storage medium includes computer instructions that, when executed on a computer, cause the computer to perform any of the methods described above.

[0022] The present invention also discloses an electronic device, wherein the electronic device includes: a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the program to implement the method described in any of the preceding descriptions.

[0023] Compared with the prior art, the present invention has the following advantages:

[0024] 1. The movable variable load upper electrode designed in this invention has a simple and compact structure, integrating three key functions: conductivity, load loading, and laser reflection. The movable variable load upper electrode itself has conductivity to meet the inherent function of an electrode, and it is also freely movable vertically. When the spherical indenter below the movable variable load upper electrode contacts the sample to be tested, it can also utilize gravity to achieve load loading, and the load magnitude can be adjusted by a counterweight. Furthermore, the insulating reflective film above the movable variable load upper electrode achieves laser reflection from the laser Doppler vibrometer (LDV) in a non-contact manner.

[0025] 2. Because the insulating reflective film positioned above the movable variable load upper electrode achieves laser reflection from the laser Doppler vibrometer (LDV) in a non-contact manner, this invention utilizes the crucial movable variable load upper electrode and the LDV to achieve non-contact strain measurement of the sample under test in this field. This fully leverages the high sensitivity, high resolution, and high response speed of the LDV in strain measurement of the sample under test. This avoids the mechanical interference introduced by traditional contact displacement sensors in existing technologies. Furthermore, the movable variable load upper electrode, positioned between the LDV and the sample, ensures that the LDV is unaffected by the ambient temperature environment of the sample through its vertical movement. This allows the LDV to achieve picometer-level displacement detection accuracy in strain measurement of the sample under test, enabling precise electrostriction testing of ferroelectric materials under complex conditions. Attached Figure Description

[0026] Figure 1 This is a schematic diagram of the architecture of a system for measuring strain in ferroelectric materials under varying temperature and load conditions, provided in one embodiment of the present invention.

[0027] Figure 2 This is a schematic diagram of a strain measurement process provided in one embodiment of the present invention;

[0028] Figure 3 This is a schematic diagram of a device control and data acquisition process provided in one embodiment of the present invention;

[0029] Figure 4 This is a schematic diagram of the structure of a movable variable load upper electrode provided in one embodiment of the present invention;

[0030] Figure 5 A schematic diagram of a strain measurement unit provided in one embodiment of the present invention;

[0031] Figure 6a This refers to the voltage signal of a ferroelectric ceramic sample measured in one embodiment of the present invention.

[0032] Figure 6b This is a real-time strain curve of a ferroelectric ceramic sample obtained in one embodiment of the present invention;

[0033] Figure 6c This is the electrostrain hysteresis loop of a ferroelectric ceramic sample measured in one embodiment of the present invention;

[0034] Figure 6d This is the electro-strain hysteresis loop of a ferroelectric ceramic sample under varying temperature conditions, as measured in one embodiment of the present invention.

[0035] Figure 6e The electrostriction loops of the ferroelectric ceramic sample measured in one embodiment of the present invention are obtained under two load conditions of 1.0 N and 5.0 N at room temperature. Detailed Implementation

[0036] The following will refer to the appendix. Figures 1 to 6e Specific embodiments of the invention are described in detail below. While specific embodiments of the invention are shown in the accompanying drawings, it should be understood that the invention can be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided to enable a more thorough understanding of the invention and to fully convey the scope of the invention to those skilled in the art.

[0037] It should be noted that certain terms are used in the specification and claims to refer to specific components. Those skilled in the art will understand that different terms may be used to refer to the same component. This specification and claims do not distinguish components based on differences in terminology, but rather on differences in function. The terms "comprising" or "including" used throughout the specification and claims are open-ended and should be interpreted as "comprising but not limited to." The following descriptions are preferred embodiments for carrying out the invention; however, these descriptions are for the purpose of understanding the general principles of the specification and are not intended to limit the scope of the invention. The scope of protection of this invention is determined by the appended claims.

[0038] To facilitate understanding of the embodiments of the present invention, further explanations and descriptions will be provided below with reference to the accompanying drawings and specific embodiments. The accompanying drawings do not constitute a limitation on the embodiments of the present invention.

[0039] In one embodiment, the present invention provides a system for measuring the electroinduced strain of ferroelectric materials under varying temperature and load conditions, such as... Figure 2As shown, the system uses a computer to control a signal generator (e.g., Precision 10kV HVI-SC, Precision Premier II), a high-voltage amplifier (e.g., TReK MODEL 609B), and a laser Doppler vibrometer to set different signal parameters (e.g., voltage, frequency, period, interval time, etc., where different voltages mean different electric field strengths), different temperature conditions, laser intensity, test range, and filter size of the laser Doppler vibrometer. A data acquisition unit collects the voltage signal generated by the signal generator and the measured displacement signal, and performs analog-to-digital conversion to obtain the respective digital signals of the voltage and displacement signals. These digital signals can then be exported as corresponding data files. This invention can further plot electrostrain curves based on the respective data files of the voltage and displacement signals, or directly based on the digital signals of the voltage and displacement signals after analog-to-digital conversion. For example, this can be done by running existing software such as Vision software in the industry, or any existing software that can treat one digital signal as the independent variable x and another digital signal as the dependent variable y, to plot the electrostrain curves.

[0040] In another embodiment, Figure 3 A structural block diagram of the equipment control and data acquisition process in the measurement method of the present invention is shown. In this embodiment, the computer 402 controls the signal generator 201, the temperature-controlled variable temperature stage 102, and the laser vibrometer 303 (exemplarily, the laser vibrometer can be a laser Doppler vibrometer) to control the test conditions. Simultaneously, the data acquired by the data acquisition card 401 mainly includes the temperature signal output by the thermocouple of the thermal field generation unit, the voltage signal of the signal generator, and the strain signal from the laser Doppler vibrometer of the strain measurement unit. Multiple signals undergo analog-to-digital conversion in the data acquisition card, ultimately obtaining a more reliable and realistic strain signal generated by the sample under test under the corresponding temperature and excitation voltage signal.

[0041] As mentioned above, optionally, the final obtained strain signal can be further processed by computer 402 after digital-to-analog conversion, using various known software or methods in the prior art to obtain an electro-strain curve. Those skilled in the art will understand that the electro-strain curve includes strain information in addition to voltage or electric field strength information, but the electro-strain curve itself does not include temperature information.

[0042] Given that this invention fully leverages the inherent advantages of laser vibrometers in a non-contact manner and achieves high-precision measurement of electro-induced strain under varying temperature conditions, and that temperature, voltage, and strain signals are all digitized during the testing process, this invention can ultimately obtain the strain signal of the sample under test at each temperature condition under the corresponding voltage / electric field strength, as well as the corresponding electro-induced strain loop at each temperature condition, and can digitize all information including temperature, voltage / electric field strength, strain, and electro-induced strain loop.

[0043] In another embodiment, the present invention discloses a system for measuring the electrostrain of ferroelectric materials under varying temperature and load conditions, the system comprising:

[0044] Thermal field generating unit, movable variable load upper electrode and laser vibration meter;

[0045] The system uses a thermal field generating unit to control the temperature of the sample to be tested. The thermal field generating unit is used to set the temperature and can make the temperature change according to the test requirements.

[0046] The system applies a variable electric field and force load to the sample under test using a movable variable load upper electrode, while simultaneously using the movement of the movable variable load upper electrode during the test to conduct the minute mechanical displacement of the sample under test caused by electrostrain; wherein, the force load is adjusted by different configurations of the counterweights of the movable variable load upper electrode.

[0047] The system uses a laser vibrometer to focus a laser beam onto the upper surface of a movable variable load electrode, and measures the displacement signal of the movable variable load electrode non-contactly via an insulating reflective film set on the electrode, so as to accurately obtain the strain signal caused by the electro-strain of the sample under test.

[0048] In another embodiment, the present invention also discloses a method for measuring the electrostrain of ferroelectric materials under varying temperature and load conditions, comprising the following steps:

[0049] The temperature can be set by the thermal field generation unit and can be changed according to the test requirements.

[0050] The test signal generation unit is used to generate voltage excitation and can make the voltage excitation change according to the test requirements.

[0051] The minute mechanical displacement of the sample under test caused by electro-induced strain is measured by a strain measurement unit.

[0052] Furthermore, the method utilizes a device control and data analysis unit to generate electro-induced strain loops.

[0053] In another embodiment, the present invention also discloses a method for measuring the electrostrain of ferroelectric materials under varying temperature and load conditions, the method comprising:

[0054] It can set the temperature and make the temperature change according to the test requirements to control the temperature of the sample to be tested;

[0055] A variable electric field and load are applied to the sample under test using a movable variable load upper electrode. At the same time, the movement of the movable variable load upper electrode during the test transmits the minute mechanical displacement of the sample under test caused by electrostrain. The load is applied by the gravity of the movable variable load upper electrode and optional counterweights and varies with different configurations of the counterweights.

[0056] A laser vibrometer is used to focus a laser beam onto the upper surface of a movable variable load electrode. The displacement signal of the movable variable load electrode is measured non-contactly via an insulating reflective film on the electrode, thereby indirectly measuring the strain signal caused by the electro-strain of the sample under test.

[0057] Preferably, after the signal is converted from analog to digital, the corresponding data is processed and an electro-strain curve is generated.

[0058] The following, in conjunction with the accompanying drawings and embodiments, describes in more detail the system and method for measuring the electrostrain of ferroelectric materials under varying temperature and load conditions. Specifically:

[0059] In another embodiment, Figure 1 This is a schematic diagram of the system architecture for measuring the electrostrain of ferroelectric materials under varying temperature and load conditions, as disclosed in this invention. Figure 1 As shown, the system includes:

[0060] The thermal field generating unit 1 is used to control the temperature of the sample to be tested; typically, it controls the temperature and causes the temperature to change accordingly according to the test requirements to obtain the temperature variation conditions required for the test; exemplaryly, the thermal field generating unit includes a temperature control stage 102; exemplaryly, the sample to be tested is immersed in silicone oil, and the temperature of the sample to be tested is controlled by controlling the temperature of the silicone oil, as detailed below.

[0061] Test signal generation unit 2 is used to output an electric field; for example, the test signal generation unit includes a signal generator 201 and a high voltage amplifier 202; wherein, the high voltage amplifier can amplify a low voltage signal to a high voltage; it should be noted that the test signal generation unit is used to generate voltage excitation and can make the voltage excitation change according to the test requirements, so as to further apply an electric field strength to the sample under test through the movable variable load electrode during the test.

[0062] The strain measurement unit 3 is used to measure the electro-induced strain of the sample under test by means of a laser vibrometer under varying temperature and load conditions.

[0063] The equipment control and data analysis unit 4 is used to perform parameter and operation coordination control of the temperature control stage 102, the signal generator 201 and the laser vibration meter 303, and to collect and process data on the temperature signal of the thermocouple 101, the voltage signal generated by the test signal generation unit, and the strain signal of the sample to be tested measured by the laser vibration meter 303 in a non-contact manner.

[0064] In another embodiment, the thermal field generating unit includes a thermocouple 101 and a temperature-controlled variable-temperature stage 102, used to control the temperature of the sample under test by controlling the temperature of the test environment. For example, depending on the test requirements, the temperature range can be controlled from room temperature to 200 degrees Celsius. Under these variable-temperature conditions, with the electrodes and their counterweights configured on a movable variable-load, the electrostrain of the sample under test can be tested to study the changes in the electrostrain properties of the material due to temperature variations during phase transitions.

[0065] For example, thermocouple 101 measures the temperature near the sample in real time and feeds it back to the equipment control and data analysis unit 4. For instance, the temperature-controlled variable temperature stage 102 heats the sample according to the set temperature of the computer 402, ensuring that the sample's ambient temperature reaches the required testing conditions. When the temperature measured by thermocouple 101 reaches the set temperature of the temperature-controlled variable temperature stage 102, the system automatically enters a heat preservation program to ensure temperature stability during the test. Then, the temperature conditions are adjusted according to the test requirements, and the test continues under these adjusted conditions.

[0066] In another embodiment, the test signal generation unit includes a signal generator 201 and a high-voltage amplifier 202, responsible for generating the voltage excitation required for the test. The movable variable load upper electrode is responsible for applying the voltage excitation to the sample under test. The signal generator 201 has diverse parameter setting options, including signal type (e.g., bipolar or unipolar), voltage amplitude (up to ±10kV), voltage frequency (ranging from 1Hz to 1MHz), and the interval time of polarity signals (1 to 1000ms). These parameters can be finely adjusted according to the material properties of different samples under test and the testing requirements. The computer controls the signal generator 201 to output a signal that meets the set requirements. This signal is amplified by the high-voltage amplifier 202 to achieve the voltage amplitude required for the actual test, and then applied to the sample under test via the movable variable load upper electrode to achieve effective electro-strain excitation.

[0067] In another embodiment, the strain measurement unit 3 includes a movable variable load upper electrode 302 and a laser vibrometer 303 to realize a high-precision electro-induced strain testing system.

[0068] For example, the movable variable load upper electrode 302, as part of the system, is used to connect to the sample under test and apply a voltage excitation signal / electric field intensity to the sample under test. At the same time, it can conduct the small mechanical displacement of the sample caused by electro-strain through the movement of the movable variable load upper electrode. In addition, it is also used to reflect the laser reflected from the upper surface of the movable variable load upper electrode 302 to the laser vibrometer 303 so as to further measure the displacement signal of the movable variable load upper electrode through the laser vibrometer, and indirectly obtain the strain signal caused by the electro-strain of the sample under test.

[0069] Therefore, the movable variable load upper electrode of the present invention has the synergistic effect of applying voltage excitation / electric field strength / force load, conducting electro-induced strain to generate small mechanical displacement, and performing laser reflection.

[0070] In another embodiment, the strain measurement unit 3 includes a movable variable load upper electrode 302 and a laser vibrometer 303, as well as a seismic platform 301, to realize a seismic-resistant high-precision electro-strain testing system.

[0071] For example, when performing tests, see Figure 4 , Figure 5 The present invention presses the polytetrafluoroethylene insulating shell of the movable variable load upper electrode tightly onto the fixed lower electrode (exemplarily, the lower electrode is an electrode plate), so that the movable variable load upper electrode and the cooperating lower electrode form a closed space, effectively isolating external environmental interference and reducing the impact of interference such as temperature fluctuation and medium disturbance on the test signal.

[0072] It should be noted that if the test environment has significant interference from environmental vibration and noise that affects the test, and the displacement signal is extremely weak, in a more preferred embodiment of the present invention, for the anti-seismic platform 301, an air-floating anti-seismic platform with excellent seismic performance can be considered.

[0073] Therefore, in another preferred embodiment, to further reduce environmental interference, both the laser vibrometer 303 and the movable variable load upper electrode 302 are fixed to the air-floating anti-vibration platform by a stable bracket, ensuring the stability and positioning accuracy of the measuring device. It is understood that the bracket and anti-vibration platform can be purchased commercially. Furthermore, the laser vibrometer 303 is remotely controlled by a computer 402, which can adjust key parameters such as laser intensity, measurement range, and filtering frequency in real time according to testing requirements to optimize signal stability and measurement accuracy. The simulated strain signal collected by the laser vibrometer 303 is converted from analog to digital with high precision by the data acquisition card 401 and then transmitted to the computer 402 for subsequent data processing, analysis, and storage.

[0074] In another embodiment, Figure 2This diagram illustrates the system architecture of the strain measurement process in the measurement method of the present invention. Excitation signal parameters are input into the computer 402, which controls the signal generator 201 to generate the corresponding excitation signal. The signal generator 201 is connected to the high-voltage amplifier 202. The signal generated by the signal generator is input into the high-voltage amplifier, which further amplifies the signal to the actual voltage signal required for testing the sample. The amplified voltage signal is then applied to both sides of the sample under test through the movable variable load upper electrode 302 and the lower electrode that cooperates with the movable variable load upper electrode. After being excited by the voltage, the sample under test will experience a micrometer-level displacement. Since the movable variable load upper electrode applies a load to the sample under test through gravity, and maintains contact with the sample, as the sample under test displaces, the movable variable load upper electrode is equivalent to synchronously generating a corresponding displacement under the drive of the sample. Considering that the laser vibrometer 303 (e.g., a laser Doppler vibrometer) focuses the laser onto the insulating reflective film on the upper surface of the movable variable load electrode, this invention can measure the strain signal of the sample under test during the movement of the movable variable load electrode. This is a non-contact measurement, obtaining the strain signal of the sample under test by measuring the displacement signal of the movable variable load electrode. Then, the laser vibrometer transmits the measured strain signal in real time to a data acquisition card for analog-to-digital conversion, and finally inputs it into a computer for data processing.

[0075] In another embodiment, Figure 4 A schematic diagram of the movable variable load upper electrode in the measurement system of the present invention is shown. The movable variable load upper electrode includes: an insulation protection part, an electrode part, and a counterweight.

[0076] The insulating components include an insulating reflective film 11 and a polytetrafluoroethylene insulating shell 12. In addition to its insulating and protective function, the insulating reflective film is also used to receive and reflect the laser from the laser Doppler vibrometer.

[0077] The electrode assembly includes a metal slide rail 14, a high-voltage wire connector 15, and a copper electrode 16. The high-voltage wire is inserted into the high-voltage wire connector and connected to the copper electrode.

[0078] The counterweight 13 needs to be connected to the copper electrode during use. The number of counterweights can be increased or decreased depending on the specific test conditions to change the load applied to the sample under test. See also... Figure 4As shown, it illustrates two counterweights from top to bottom. It should be noted that the movable variable load upper electrode structure includes adjustable counterweights, allowing for flexible adjustment of the loading pressure according to different sample shapes and testing requirements, realistically simulating the load conditions under material service conditions. Compared to traditional spring-type or needle-shaped electrodes, the lower spherical indenter design significantly reduces issues such as off-center loading, contact instability, and stress concentration due to its unique shape, thereby improving contact consistency and test reproducibility.

[0079] Furthermore, the copper electrode 16 comprises three parts: an upper copper electrode, a middle copper electrode, and a lower copper electrode.

[0080] The counterweight 13 can be applied to the upper part of the copper electrode, for example, by fixing the counterweight to the upper part of the copper electrode with screws, or in other suitable ways;

[0081] The outer diameter of the middle part of the copper electrode is larger than the outer diameter of the upper part of the copper electrode, and the outer diameter of the upper part of the copper electrode is larger than the outer diameter of the lower part of the copper electrode.

[0082] The lower part of the copper electrode is a cylinder that is thinner than the middle and upper parts, and the lower end of the cylinder has a spherical indenter. The spherical indenter is used to conduct electricity while applying a load to increase the contact area with the sample, thereby reducing discharge and polarization phenomena. This is because the present invention increases the contact area by using the spherical indenter, reduces the local current density, thereby reducing the occurrence of discharge phenomena, and improves the interfacial mass transfer and electron transfer efficiency between the electrode and the sample.

[0083] The middle part of the copper electrode is also cylindrical, and the middle part of the copper electrode is used to fit tightly with the metal slide rail 14 so that the copper electrode can move up and down in the metal slide rail.

[0084] In addition, combined Figure 4 An annular metal slide rail 14 is provided on the outer side of the copper electrode from the inside out. Exemplarily, the annular metal slide rail is fitted over the copper electrode, particularly around the middle portion. A polytetrafluoroethylene (PTFE) insulating shell includes an upper and lower part, and the upper surface of the upper part of the copper electrode is used to mount the insulating reflective film 11. Exemplarily, the insulating reflective film and the upper surface of the upper part of the copper electrode are bonded together by adhesive or other methods that facilitate fixation and testing. The specific dimensions and morphology of the insulating reflective film are determined to ensure its use for insulation protection and for receiving and reflecting the laser from the laser vibrometer to achieve non-contact measurement of the electrostrain of the sample under test using the laser vibrometer.

[0085] In another embodiment, for multiple counterweights arranged from top to bottom, the lowest counterweight contacts the upper surface of the middle of the copper electrode; a gap exists between the upper surface of the highest counterweight and the lower surface of the upper center of the PTFE insulating shell. This is to ensure that the copper electrode has sufficient space to move up and down to ensure strain measurement.

[0086] More preferably, the length of the middle part of the copper electrode is much shorter than the length of the slide rail, and space is reserved for the maximum number of counterweights 13, ensuring that there is a gap between the upper surface of the uppermost counterweight and the lower surface of the upper center position of the polytetrafluoroethylene insulating shell. This is to ensure that the copper electrode has sufficient space to move up and down.

[0087] More preferably, in another embodiment, when the upper surface of the PTFE insulating shell is lower than the upper surface of the copper electrode, the lower surface of the PTFE insulating shell can be horizontally flush with the transition point between the cylinder and the spherical indenter at the lower part of the copper electrode; and there is a gap between the upper surface of the uppermost counterweight and the lower surface of the center position of the upper PTFE insulating shell. This ensures that not only the copper electrode has sufficient space to move up and down, but also that the spherical indenter has sufficient space to move up and down.

[0088] In another embodiment, see Figure 4 ,

[0089] A limiter 17 is provided on one inner surface of the lower part of the metal slide rail. The limiter is used to prevent the lower surface of the middle part of the copper electrode from exceeding the bottom surface of the metal slide rail during downward movement and causing improper contact between the spherical indenter and the sample. When a limiter is provided on each of the two symmetrical inner surfaces of the lower part of the metal slide rail, it further ensures the limiting function. The lower part of the polytetrafluoroethylene insulating shell has two surfaces, upper and lower, with a hollow area in the middle of the two surfaces. The upper surface is used to fix and support the bottom surface of the metal slide rail and the bottom surface of the limiter. The center of the upper surface and the center of the lower surface have through holes, so that the cylinder and spherical indenter at the lower part of the copper electrode can move up and down in the longitudinal direction of the through holes. For example, the limiter can be fixed and supported on the upper surface of the lower part of the PTFE insulating shell by screws or any other suitable means. Whether it is tightly connected to the metal slide rail on one side is not a mandatory requirement. If necessary, the limiter can be further fixed by screws, adhesive, clips, or any other means that can securely connect it to the metal slide rail. Furthermore, more preferably, the limiter is easy to disassemble, and the copper electrode and counterweight can be separated or reassembled by disassembling the limiter to facilitate the disassembly and assembly of different counterweights.

[0090] See further Figure 4In another embodiment, a thermocouple 18 is disposed below the metal slide rail on at least one side. One end of the thermocouple is disposed laterally on the inner surface of the lower part of the polytetrafluoroethylene insulating shell, and the other end of the thermocouple is disposed laterally without extending beyond the inner surface of the metal slide rail above it. This prevents the copper electrode from scraping against the thermocouple during vertical movement, even if all limiters malfunction or are damaged for unknown reasons in extreme cases.

[0091] In another embodiment, see Figure 4 ,

[0092] At a height corresponding to the upper and lower surfaces of the middle part of the copper electrode, a through hole is laterally opened on one side of the metal slide rail, and further laterally passes through the polytetrafluoroethylene insulating shell to provide the connection port 15 for the high-voltage wire. The shape of the through hole is adapted to the connection port of the high-voltage wire, and can be irregular or regular.

[0093] In another embodiment, Figure 5 This diagram illustrates the strain measurement unit device in the measurement system of the present invention. During testing, the temperature-controlled variable temperature stage 102, petri dish 19, sample 20, movable variable load upper electrode 302, lower electrode 21, and laser vibration meter 303 (e.g., laser Doppler vibration meter) are all placed on the vibration-resistant platform 301 to reduce the impact of external vibrations on the test. Specifically,

[0094] The lower end of the temperature-controlled variable temperature stage 102 and the anti-vibration platform 301 are fixed together. A petri dish is placed on the upper surface of the temperature-controlled variable temperature stage 102 and fixed. Silicone oil, an electrode plate, and the sample to be tested are placed in the petri dish, and the electrode plate and the sample to be tested are submerged in silicone oil. This prevents the sample from being electrically broken down during the test. In addition, the movable variable load upper electrode and the laser Doppler vibrometer are fixed directly above the sample to be tested from bottom to top by a movable bracket. At the same time, the movable variable load upper electrode and the laser Doppler vibrometer can be flexibly adjusted up and down through the bracket. The laser Doppler vibrometer is located at a certain distance directly above the insulating reflective film in the movable variable load upper electrode. And the spherical indenter in the movable variable load upper electrode is located directly above the sample to be tested.

[0095] In summary, it can be understood that:

[0096] The movable variable load top electrode designed in this invention has a simple and compact structure, integrating three key functions: conductivity, electric field / load loading, and laser reflection. The movable variable load top electrode itself has conductivity to meet the inherent function of an electrode (e.g., using a copper electrode). Furthermore, due to its vertical mobility, when the spherical indenter below the movable variable load top electrode contacts the sample under test, it can utilize gravity to achieve load loading, and the load intensity can be adjusted by a counterweight. In addition, the insulating reflective film above the movable variable load top electrode achieves laser reflection from the laser Doppler vibrometer (LDV) in a non-contact manner.

[0097] Because the insulating reflective film positioned above the movable variable load electrode achieves laser reflection from the laser vibrometer in a non-contact manner, this invention utilizes the crucial movable variable load electrode and laser vibrometer to achieve non-contact, high-precision strain measurement of the sample under test. This fully leverages the high sensitivity, high resolution, and high response speed of the laser vibrometer in strain measurement of samples under test. This avoids the mechanical interference introduced by traditional contact displacement sensors in existing technologies, thus enabling the laser vibrometer to achieve picometer-level displacement detection accuracy in strain measurement of samples under test, facilitating the testing of ferroelectric properties under extremely small deformations. Furthermore, this invention helps extend this non-contact strain measurement technique using a laser vibrometer and sample to complex thermal and media environments, because it not only controls the temperature of the sample under test but also fully utilizes the inherent excellent characteristics of the laser vibrometer.

[0098] In another embodiment, the fixed movable variable load upper electrode, the laser Doppler vibrometer, and the support form a whole, and finally the support base is connected to the anti-vibration platform. During testing, the PTFE insulating shell of the movable variable load upper electrode needs to be tightly pressed against the lower electrode that works in conjunction with the movable variable load upper electrode to form a relatively sealed cavity, while the entire copper electrode is pressed onto the sample under test by gravity. For example, based on experimental experience, the entire copper electrode has approximately 0.8 cm of free space in the vertical direction. For example, the space for the copper electrode to move vertically in the movable variable load upper electrode is such that the electrode can move vertically within a range of -0.3 cm to 0.5 cm, that is, within a range of 0.8 cm, where 0 cm is the lowest point of the PTFE insulating shell.

[0099] It is understandable that the movable variable load upper electrode, through its outermost polytetrafluoroethylene insulating shell, together with the lower electrode, forms a relatively closed measurement cavity. This not only enables controllable internal temperature but also effectively isolates external environmental interference, reducing the impact of temperature fluctuations and medium disturbances on the test signal, thereby significantly improving the system's thermal stability and measurement accuracy.

[0100] Furthermore, since the upper surface of the copper electrode is used to mount the insulating reflective film 11, and this insulating reflective film not only serves for insulation protection but also for receiving and reflecting the laser from the laser vibrometer to achieve non-contact measurement, therefore, in combination with... Figure 5 It is understood that this method of setting the insulating reflective film keeps it away from the petri dish, the silicone oil, and the heating area, thereby enabling the present invention to reduce the influence of different media and temperatures on the laser and further ensure the accuracy of the measurement.

[0101] For example, since the sample to be tested is placed in a petri dish, the present invention is applicable to ferroelectric material samples of various forms, including bulk materials, thin films, polymers, etc., and can operate stably for a long time in a silicone oil-covered environment. According to actual testing, it can operate stably for 6-8 hours.

[0102] In the embodiment of this invention using a laser Doppler vibrometer, because this invention fully utilizes the wide frequency response characteristic of the laser Doppler vibrometer, covering 1Hz to 1MHz, it can adapt to comprehensive testing needs from extremely low-frequency slow strain behavior to high-frequency transient response, meeting the dynamic strain testing requirements of ferroelectric materials under different working conditions. This constitutes a significant difference between this invention and existing technologies. Therefore, the system disclosed in this invention has good versatility and platform compatibility, and the overall device structure is relatively simple. The components are easily standardized, it is more tolerant of measurement environment requirements, and has lower signal input requirements, fully leveraging the advantage of the laser vibrometer's wide frequency range coverage (e.g., 1Hz to 1MHz). Furthermore, the voltage and displacement signals generated during the test can be independently acquired and transmitted in real time to a computer or other data processing equipment. Based on its testing principle, the data reliability of the entire testing process is better than that of traditional solutions in existing technologies.

[0103] In summary, the system disclosed in this invention is advantageous for integration into existing ferroelectric performance testing platforms.

[0104] In another embodiment, the present invention discloses a method for measuring the electroinduced strain of ferroelectric materials, comprising the following steps:

[0105] The laser vibrometer and the movable variable load upper electrode are each placed vertically on the support. The laser is adjusted to focus on the insulating reflective film of the movable variable load upper electrode. A petri dish containing silicone oil and the sample to be tested is placed below the movable variable load upper electrode. Below the petri dish is a temperature-controlled variable temperature stage, and the components above the petri dish are placed on an air-floating anti-vibration platform. For example, the ceramic sample is completely immersed in high-temperature silicone oil to stabilize the test environment and avoid electrical breakdown.

[0106] Connect the signal generator, high voltage amplifier, movable variable load upper electrode, and sample under test to form a test circuit loop;

[0107] Connect the signal generating unit, temperature changing unit, laser vibration meter, data acquisition card, and computer to achieve data acquisition and equipment control.

[0108] The sample under test is a fixed lower electrode, while the sample under test is positioned above a spherical indenter aligned with a movable variable load upper electrode.

[0109] By adjusting the support position of the movable variable load upper electrode, the PTFE insulating shell of the upper electrode is tightly pressed against the surface of the lower electrode. The spherical indenter, through the movable variable load upper electrode and an optional counterweight, naturally presses the gravitational load onto the sample under test, simulating the vertical force boundary conditions of the device corresponding to the sample in practical applications. It can be seen that this invention ensures uniform force on the sample and further ensures stable electrode contact without requiring additional loading mechanisms beyond the movable variable load upper electrode and optional counterweight.

[0110] Based on the waveform, voltage magnitude, frequency, temperature, etc. of the test signal, different test conditions under varying temperature and load conditions are achieved, the test range of the laser vibrometer is adjusted, and the analog signal during the electro-strain test is digitally acquired through the data acquisition card based on analog-to-digital conversion.

[0111] Meanwhile, during the test, a temperature-controlled variable temperature stage is used for heating or cooling. When the temperature measured by the thermocouple matches the set temperature, the heat preservation program is initiated. The computer is manually or automatically controlled to trigger the signal to start the test, and the data acquisition card begins to collect voltage and strain signals during the test. During the test, a new round of testing under variable temperature and load conditions is implemented according to the test requirements. Typically, the reason why this invention enables testing under variable temperature and load conditions is to take ceramic electrostriction test samples as an example, which will undergo a phase transition when the temperature changes, and the strain will change with the temperature.

[0112] The computer automatically saves the digital voltage and strain signals transmitted by the data acquisition card, and processes the data into an electro-strain curve using existing technology.

[0113] The following are more specific test examples, in which:

[0114] Specific test example 1:

[0115] This test case uses BS6T (BaSn) 6% Ti 94% O3 ceramic was used as the test sample, with a thickness of 0.737 mm and an electrode area of ​​0.608 cm². 2 The applied electric field strength was set to 30 kV / cm, corresponding to a voltage amplitude of 2211 V; the excitation signal used a standard bipolar triangular wave with a frequency of 5 Hz. The test load was 500 g (i.e., the movable variable load upper electrode + counterweight), generating a vertical gravitational load of approximately 5.0 N, at room temperature.

[0116] During testing, the ceramic sample was completely immersed in high-temperature silicone oil to stabilize the testing environment and prevent electrical breakdown. A fixed lower electrode was positioned below the sample, and a movable, variable-load upper copper electrode was aligned and mounted above it. By adjusting the position of the electrode on the support, the PTFE shell of the movable, variable-load upper electrode was tightly pressed against the surface of the lower electrode. The movable, variable-load upper electrode and an optional counterweight naturally pressed onto the sample by gravity to apply a load, thus simulating the vertical force boundary conditions of the device in practical applications. It was found that this invention ensures uniform force on the sample and stable electrode contact without the need for an additional loading mechanism.

[0117] Subsequently, the position of the laser Doppler vibrometer (LDV) was adjusted so that its laser beam was focused onto the insulating reflective film on the upper surface of the movable variable load electrode. Throughout the process, the aforementioned voltage excitation parameters were controlled by a computer.

[0118] The sample under test undergoes minute strain under the excitation of an electric field, causing the electrodes on the movable variable load to move synchronously. The insulating reflective film moves accordingly, and a laser Doppler vibrometer (LDV) detects the changes in the reflected laser signal in real time and outputs the displacement information. The voltage and displacement signals are synchronously transmitted to a data acquisition card for analog-to-digital conversion. Finally, the generated raw electric field waveform data ( Figure 6a The data shows that the original electric field was a triangular wave, and a slight discharge phenomenon occurred during the voltage increase; the real-time strain curve of the original displacement waveform data ( Figure 6b This indicates that even with an increase in the number of sampling points over time, the real-time strain curve remains smooth, indicating minimal impact from environmental vibrations and no interference with the test. The final electro-strain curve obtained based on the voltage and strain signals is shown below. Figure 6c As shown, the above data all maintained good originality, and the entire testing process was authentic and reliable.

[0119] Specific test example 2:

[0120] This test case uses PNN-PZT(0.5PbNi) 0.33 Nb 0.67 O3-0.5PbZr 0.3 Ti 0.7 O3) ceramic material was used as the test sample, with a thickness of 1.0 mm and an electrode area of ​​0.2641 cm². 2 The applied electric field strength was 35 kV / cm, corresponding to an excitation voltage amplitude of 3500 V. The voltage waveform was a standard bipolar triangular wave with a frequency of 10 Hz. The temperature range was set from 20℃ to 180℃, with measurements taken every 20℃ from 20℃ to 120℃ and every 20℃ from 120℃ to 180℃, for a total of 12 temperature points. The test load was 500g (i.e., the movable variable load upper electrode + counterweight), generating a vertical gravitational load of approximately 4.9 N.

[0121] The test procedure for specific test example 2 is the same as that for specific test example 1. The computer controls the heating of the thermal field unit to reach the set value, with thermocouples providing real-time feedback and maintaining temperature stability. Once the target temperature is reached, a signal to start the test is triggered, and a voltage excitation signal is applied to the sample under test. A laser Doppler vibration meter (LDV) acquires the strain signal in real time. The voltage and displacement signals are synchronously transmitted to the data acquisition card and converted from analog to digital. The above process is repeated to obtain electrostricted strain curves at different temperature points, such as... Figure 6d The multiple electro-strain loops shown.

[0122] The above two test examples, their test processes, and test results demonstrate that the present invention can efficiently, stably, and accurately test the electro-strain of ferroelectric materials within a wide temperature range and obtain the corresponding electro-strain hysteresis loop. The present invention is obviously applicable to the performance evaluation of ferroelectric materials and the testing of engineering devices under multiple temperature fields.

[0123] The following are two test cases involving variable loads.

[0124] Specific test example 3:

[0125] This test example uses BNT-based ceramic material as the test sample, with a sample thickness of 0.355 mm and an electrode area of ​​0.193 cm². 2 The applied electric field strength is 70 kV / cm, corresponding to an excitation voltage amplitude of 24850 V. The voltage waveform is a standard bipolar triangular wave with a frequency of 10 Hz. Tested at room temperature with a load of 100 g (e.g., without counterweights, gravity comes only from the upper electrode of the movable variable load), the resulting vertical gravitational load is approximately 1.0 N.

[0126] Specific test example 4:

[0127] This test example uses the BNT-based ceramic material from specific test example 3 as the test sample. The sample thickness is 0.355 mm, and the electrode area is 0.193 cm². 2 The applied electric field strength was 70 kV / cm, corresponding to an excitation voltage amplitude of 24850 V. The voltage waveform was a standard bipolar triangular wave with a frequency of 10 Hz. Tested at room temperature with a load of 500 g (i.e., the movable variable load upper electrode + counterweight), the resulting vertical gravitational load was approximately 4.9 N.

[0128] The testing procedures for specific test examples 3 and 4 are the same as those for specific test examples 1 and 2 mentioned above. For example... Figure 6e As shown, it illustrates the electrostrain hysteresis loops of the aforementioned BNT-based ceramic material as a test sample under two load conditions of 1.0 N and 5.0 N at room temperature. Therefore, it can be seen that the system and method disclosed in this invention, in addition to measuring the electrostrain of ferroelectric materials at different temperature points (i.e., under varying temperature conditions), can also achieve the measurement of the electrostrain of ferroelectric materials under varying load conditions.

[0129] In another embodiment, the present invention also discloses a computer storage medium comprising computer instructions that, when executed on a computer, cause the computer to perform any of the methods described above.

[0130] In another embodiment, the present invention also discloses an electronic device comprising: a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the program to implement the method described in any of the preceding descriptions.

[0131] The applicant has provided a detailed description of the embodiments of the present invention in conjunction with the accompanying drawings. However, those skilled in the art should understand that the above embodiments are merely preferred examples of the present invention and are not limited to the specific embodiments described above. The detailed description is intended to help readers better understand the spirit of the present invention and is not intended to limit the scope of protection of the present invention. On the contrary, any improvements or modifications made based on the inventive spirit of the present invention should be included within the scope of protection of the present invention.

Claims

1. A system for measuring the electrostrain of ferroelectric materials under varying temperature and load conditions, characterized in that, The system includes: Thermal field generating unit, movable variable load upper electrode and laser vibration meter; The system uses a thermal field generating unit to control the temperature of the sample to be tested. The thermal field generating unit is used to set the temperature and can adjust the temperature according to the test requirements. The system uses a movable variable load upper electrode to apply a variable electric field strength and force load to the sample under test. The small mechanical displacement of the sample under test caused by the electro-strain effect is transmitted through the movement of the movable variable load upper electrode during the test. At the same time, the operating temperature of the laser vibrometer can be kept away from the influence of the thermal field generating unit. The force load is adjusted by different configurations of the counterweights of the movable variable load upper electrode. The system uses a laser vibrometer to focus a laser beam onto the upper surface of a movable variable load electrode, and measures the real-time displacement signal of the movable variable load electrode non-contactly via an insulating reflective film set on the electrode, so as to obtain the electro-strain signal of the sample under varying temperature and load conditions.

2. The system according to claim 1, characterized in that, Preferably, the system further includes a test signal generation and amplification unit, which is used to apply adjustable DC and AC voltage excitation to the sample under test according to the test requirements.

3. The system according to claim 1, characterized in that, The system also includes an equipment control and data analysis unit, which processes the data corresponding to the signal after the signal is converted from analog to digital and uses it to generate an electro-strain loop and a real-time strain curve.

4. The system according to claim 1, characterized in that, An insulating reflective film is provided on the upper surface of the movable variable load upper electrode, which is used not only for insulation protection, but also for receiving and reflecting the laser from the laser vibrometer.

5. The system according to claim 1, characterized in that, The movable variable load upper electrode also includes a copper electrode; the lower end of the copper electrode is a spherical pressure head, which is used to conduct electricity while increasing the contact area with the sample by applying a load.

6. The system according to claim 5, characterized in that, The movable variable load upper electrode also includes: a counterweight; by changing the specifications and number of the counterweights, the force load applied to the sample to be tested can be changed.

7. A method for measuring the electrostrain of ferroelectric materials under varying temperature and load conditions, characterized in that, The method includes: It can set the temperature and make the temperature change according to the test requirements to control the temperature of the sample to be tested; A movable variable load upper electrode is used to apply a variable electric field strength and force load to the sample under test. The small mechanical displacement of the sample under test caused by electrostrain is transmitted through the movement of the movable variable load upper electrode during the test. At the same time, the operating temperature of the laser vibrometer can be kept away from the influence of the thermal field generating unit. The force load is adjusted by different configurations of the counterweights of the movable variable load upper electrode. A laser vibrometer is used to focus a laser beam onto the upper surface of a movable variable load electrode. The real-time displacement signal of the movable variable load electrode is measured non-contactly via an insulating reflective film on the electrode, thereby obtaining the displacement signal caused by the electrostrain of the sample under test.

8. The method according to claim 7, characterized in that The method further includes: processing the data corresponding to the signal after the signal is converted from analog to digital and generating electro-strain loops and real-time strain curves under varying temperature and load conditions.

9. A computer storage medium, wherein, The storage medium includes computer instructions that, when run on a computer, cause the computer to perform the method of claim 7 or 8.

10. An electronic device, wherein, The electronic device includes: a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor, when executing the program, implements the method of claim 7 or 8.

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