Application of a class of semi-heusler alloys as piezoelectric materials

Abstract

The application relates to the technical field of piezoelectric materials, and discloses application of a kind of half Heusler alloy as piezoelectric material, the half Heusler alloy is of chemical formula XYZ, wherein X is any one of Ti, Zr, Hf, V, Nb, Ta, Re or solid solution in any proportion, Y is Fe or Co or Ni, and Z is Sn or Sb or Bi.The inventor finds that the above-mentioned half Heusler alloy can exhibit excellent piezoelectric performance, wherein a [111] cut type wafer of ZrNiSn single crystal material can obtain a piezoelectric coefficient of 22 pC / N at 300 K.The half Heusler alloy has good thermal stability and structural stability in the temperature range from room temperature to 1173 K, and has great high-temperature piezoelectric application potential.A piezoelectric sensor prepared based on the above-mentioned half Heusler alloy can obtain a voltage response of the order of sub-mV under the normal pressing force of a human body, and can be used for the development of electronic devices such as piezoelectric sensors, piezoelectric vibration energy collectors and piezoelectric self-powered systems.

Description

Technical Field

[0001] This invention relates to the field of piezoelectric materials technology, specifically to the application of a type of semi-Hessler alloy as a piezoelectric material. Background Technology

[0002] Semi-Hessler alloys are a large class of intermetallic compounds with a composition of XYZ and crystallographic space group 216. X, Y, and Z are all metallic elements, each occupying a face-centered cubic sublattice, exhibiting overall non-centrosymmetric characteristics. The sum of the outermost electrons of each element follows the 18-electron rule, making them a class of narrow bandgap (E0). g Semiconductor materials with a voltage of <1.0 eV have never been experimentally reported as piezoelectric materials or piezoelectric devices.

[0003] Semi-Hersler alloys exhibit excellent mechanical properties, high-temperature thermal stability and corrosion resistance, as well as a variety of physical properties including thermoelectric effect, superconductivity and shape memory effect, and are currently being widely studied in the field of functional materials research.

[0004] Piezoelectric materials are functional materials that can directly convert between electrical energy and mechanical energy. These materials can deform in response to changes in an electric field, or generate an electric field during deformation. They play a crucial role in many fields, including aerospace, energy exploration, information technology, the automotive industry, robotics, and optoelectronics.

[0005] Previous research on piezoelectric materials has mainly focused on materials with a wide bandgap (E). g >2.0eV), low conductivity (~10) -15 Non-centrosymmetric single crystals and polycrystalline ceramics with S / m characteristics. Common piezoelectric single crystals include quartz, zincblende, and group III-V and II-VI broadband semiconductors. Quartz crystals are stable, have high mechanical strength, and good insulation properties, but are expensive and have a small piezoelectric coefficient, generally only used in standard instruments or sensors with high requirements. Lead zirconate titanate is a class of high-performance polycrystalline piezoelectric ceramics, dominating the field of piezoelectric materials due to its excellent room-temperature piezoelectric properties, electromechanical coupling properties, and high Curie temperature. However, the high lead content of lead zirconate titanate ceramics poses a significant threat to the environment and human health.

[0006] Piezoelectric materials lose their piezoelectric properties above the Curie temperature, which is a key factor hindering their application in high-temperature sensing and other applications. Currently, commercially available lead zirconate titanate piezoelectric ceramics have a Curie temperature around 600K. For example, CN107082632A discloses a piezoelectric material and its preparation method adapted to high-temperature environments. This material is characterized by a LiGeSiO5 composite structure, a high Curie temperature of 500-600℃, and high sensitivity. This invention also proposes a preparation method for this material. First, Li and Ge raw materials are mechanically alloyed in a high-energy ball mill. Then, they are mixed with an organic solvent to form a slurry, which is then co-dispersed with silica gel. After pressing and sintering, the high Curie temperature piezoelectric material LiGeSiO5 is obtained. The preparation method is simple, low-cost, and produces a stable piezoelectric signal. The material inherits the advantages of SiO2 quartz materials, exhibiting good environmental stability and a high Curie transition temperature.

[0007] Even quartz crystals with high Curie temperatures cannot maintain their piezoelectric properties above 850 K. Currently, research on piezoelectric materials applied in the >1000 K high-temperature range is relatively scarce. Developing new lead-free high-temperature piezoelectric material systems is currently a major focus of research in this field. Narrow-bandgap semiconductors with non-centrosymmetric crystal structures have long been neglected due to their high conductivity hindering effective charge accumulation and stable voltage response maintenance; their piezoelectric properties are therefore largely ignored. Summary of the Invention

[0008] This invention addresses the shortcomings in existing research on high-temperature lead-free piezoelectric materials by proposing for the first time the application of a class of semi-Hessler alloys as piezoelectric materials, and discovering that these narrow bandgap (E... g <1.0eV), high conductivity (room temperature conductivity ~10). 4 The semi-Hessler alloy (S / m, which is more than 10 orders of magnitude higher than that of traditional piezoelectric materials) exhibits a piezoelectric coefficient of up to 22 pC / N at room temperature and has piezoelectric stability in a temperature range from room temperature to 1173 K.

[0009] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0010] The application of a type of semi-Hessler alloy as a piezoelectric material, wherein the chemical formula of the semi-Hessler alloy is XYZ, wherein X = any one or more rare earth elements in any proportion of solid solution, Y = Fe or Co or Ni, and Z = Sn or Sb or Bi.

[0011] The inventors discovered that the aforementioned semi-Hessler alloy exhibits excellent piezoelectric properties, with the ZrNiSn single crystal material

[111] cut wafer achieving a piezoelectric coefficient of 22 pC / N at 300 K. Furthermore, based on the good thermal and structural stability of the semi-Hessler alloy in the temperature range from room temperature to 1173 K, it has great potential for high-temperature piezoelectric applications.

[0012] The absolute value of the piezoelectric coefficient of the semi-Hessler alloy at 300K to 1173K is above 5pC / N, preferably above 10pC / N, and even more preferably above 15pC / N.

[0013] The rare earth elements include any one of scandium (Sc), yttrium (Y), lanthanum (La), cerium (Ce), praseodymium (Pr), neodymium (Nd), promethium (Pm), samarium (Sm), europium (Eu), gadolinium (Gd), terbium (Tb), dysprosium (Dy), holmium (Ho), erbium (Er), thulium (Tm), ytterbium (Yb), and lutetium (Lu).

[0014] Preferably, the chemical formula of the semi-Hessler alloy is XYZ, wherein X = any one or more of Ti, Zr, Hf, V, Nb, Ta, Sc, Y, Dy, Er, Tm, and Lu in any proportion, Y = Fe, Co, or Ni, and Z = Sn, Sb, or Bi.

[0015] Preferably, the chemical formula of the semi-Hessler alloy is XYZ, wherein X = any one or more of Ti, Zr, Hf, and Sc in any proportion, Y = Co or Ni, and Z = Sn or Sb;

[0016] More preferably, the semi-Hessler alloy is any one of TiNiSn, ZrNiSn, HfNiSn, TiCoSb, and ScNiSb.

[0017] In the semi-Hessler alloy, the sum of the outermost electrons of the X, Y, and Z atoms satisfies the 18-electron rule, thus exhibiting a narrow bandgap semiconductor material.

[0018] The semi-Hessler alloy can be single-crystal or polycrystalline. Both single-crystal and polycrystalline versions of this alloy exhibit excellent piezoelectric properties.

[0019] Preferably, the semi-Hessler alloy is ZrNiSn, which exhibits high piezoelectric properties in both single crystal and polycrystalline forms.

[0020] Preferably, the single crystal is prepared by self-flux growth, using Z element metal as self-flux.

[0021] Preferably, the polycrystalline material is formed by sequentially melting, crushing, and sintering. The melting includes any one of suspension melting, electric arc melting, and induction melting, and the sintering is discharge plasma sintering or hot pressing sintering.

[0022] This invention also provides an application of a type of semi-Hersler alloy in high-temperature piezoelectric sensing, including the semi-Hersler alloy, wherein the stable operating temperature of the semi-Hersler alloy is 1-1500K. The preferred operating temperature is 300-1200K. Testing has revealed that the semi-Hersler alloy exhibits excellent high-temperature piezoelectric stability, displaying similar piezoelectric coefficient values ​​from 300K to 1173K.

[0023] This invention also provides a method for testing the piezoelectric coefficient of a type of semi-Hessler alloy single crystal, wherein the chemical formula of the semi-Hessler alloy is XYZ, wherein X = any one or more of Ti, Zr, Hf, V, Nb, Ta, and rare earth elements in any proportion, Y = Fe, Co, or Ni, and Z = Sn, Sb, or Bi; the piezoelectric coefficient of the semi-Hessler alloy is measured by a

[111] -cut wafer. The

[111] -cut wafer is a semi-Hessler single crystal (ZYwl) with a -45° / -35.26° tangent as defined under the IEEE 1978 standard.

[0024] The present invention also provides a piezoelectric device based on a half-Hessler alloy, comprising the half-Hessler alloy and electrodes. The piezoelectric sensor can obtain a stable voltage output under constant force applied at a fixed frequency. For example, the piezoelectric device includes any one of a piezoelectric sensor, a piezoelectric vibration energy harvester, or a piezoelectric self-powered system.

[0025] In some embodiments, the absolute value of the voltage response obtained by the piezoelectric sensor under normal human pressure is greater than 0.05mV; in some embodiments, the absolute value of the voltage response obtained by the piezoelectric sensor device prepared using the single crystal

[111] cut wafer of the half-Hersler alloy is greater than 0.15mV under a pressure of 22N at a temperature of 300K.

[0026] In some embodiments, the piezoelectric sensor made using the polycrystalline material of the semi-Hessler alloy exhibits an absolute voltage response of over 0.10 mV at a temperature of 300 K under normal human pressure (approximately 15-16 N).

[0027] The present invention also provides a piezoelectric vibration energy harvester, comprising a half-Hersler alloy, electrodes, a Zener diode, a bridge rectifier, and a capacitor; the half-Hersler alloy and the electrodes are connected together, and the electrodes are connected to the Zener diode, the bridge rectifier, and the capacitor circuit.

[0028] In some methods, the piezoelectric vibration energy harvester accumulates a voltage of over 2mV within 30 seconds under normal human body pressure.

[0029] The present invention also provides an electronic device, including the aforementioned piezoelectric device. The electronic device includes those fabricated using the positive piezoelectric effect of the semi-Hessler alloy XYZ, such as automotive collision sensors, pressure sensors, vibration-generating devices, and medical devices.

[0030] Compared with the prior art, the present invention has the following beneficial effects:

[0031] (1) This invention first discovers and confirms the piezoelectric properties of a class of semi-Hessler alloys. The single crystal or polycrystalline form of this material has a piezoelectric coefficient comparable to that of quartz crystal. When used to prepare piezoelectric devices, it can obtain an open-circuit voltage response of more than 0.05mV under normal human pressure.

[0032] (2) The semi-Hersler alloy in this invention exhibits excellent piezoelectric stability at high temperatures, with the piezoelectric coefficient remaining unchanged from 300K to 1173K, which is beneficial for the development and application of high-temperature piezoelectric sensor devices.

[0033] (3) The semi-Hessler alloy material in this invention does not contain lead, which helps to solve the environmental and human health hazards of lead components in commercial lead zirconate titanate piezoelectric ceramics. Attached Figure Description

[0034] Figure 1 The single-crystal X-ray diffraction patterns of the semi-Hessler alloy single crystals prepared in Examples 1-3 are shown.

[0035] Figure 2 Laue X-ray diffraction patterns of the semi-Hessler alloy single crystals prepared in Examples 1-3.

[0036] Figure 3 The piezoelectric coefficient of the

[111] -cut wafer of the semi-Hessler alloy single crystal prepared in Examples 1-3 at 300K.

[0037] Figure 4 The piezoelectric coefficient of the

[111] -cut wafer of the semi-Hessler alloy single crystal prepared in Examples 1-3 varies with temperature.

[0038] Figure 5 The X-ray diffraction patterns are for the semi-Hessler alloy polycrystals prepared in Examples 4-8.

[0039] Figure 6 The piezoelectric coefficient of the semi-Hessler alloy polycrystalline materials prepared in Examples 4-8 at 300K.

[0040] Figure 7 The graph shows the change of open-circuit voltage over time under pressure measurement for the semi-Hessler alloy single crystal piezoelectric device prepared in Example 9.

[0041] Figure 8 The graph shows the cumulative stored voltage over time under pressure measurement for the semi-Hessler alloy single crystal piezoelectric device prepared in Example 9.

[0042] Figure 9 The graph shows the change of open-circuit voltage over time under pressure measurement for the semi-Hessler alloy polycrystalline piezoelectric sensor devices prepared in Examples 10-13. Detailed Implementation

[0043] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention. Modifications or equivalent substitutions made by those skilled in the art based on their understanding of the technical solutions of this invention, without departing from the spirit and scope of the invention, should be covered within the protection scope of this invention.

[0044] The raw materials used in the following specific embodiments are all high-purity samples. The Ti (99.9% purity), Zr (99.9% purity), Hf (99.9% purity), Sc (99.9% purity), Ni (99.9% purity), Co (99.9% purity), Sn (99.9% purity), and Sb (99.9% purity) used were all purchased from Zhongjin Research.

[0045] Example 1

[0046] After weighing the raw materials according to the stoichiometric ratio of Ti:Co:Sb = 1:1:10, they were placed into an alumina crucible in an argon-protected glove box. The alumina crucible was then sealed under vacuum in a quartz tube. The quartz tube was heated from room temperature to 1423 K over 12 hours, held at 1423 K for 48 hours, and then slowly cooled to 1023 K at a cooling rate of 2 K / h. Excess flux was removed using a centrifuge at 1500 rpm at 1023 K to obtain TiCoSb single crystal samples.

[0047] The single crystal prepared in this embodiment was subjected to phase analysis using a Bruker D8 Venture single-crystal X-ray diffractometer equipped with Mo-palladium. The results are as follows: Figure 1 As shown, it was confirmed to be a semi-Hessler alloy structure, i.e., a cubic structure. The space group number is 216.

[0048] The orientation of the single crystal was determined using a Photonic Science Laue X-ray diffractometer, focusing on the exposed crystal planes of the preferentially grown single crystal. The results are as follows: Figure 2 As shown, the crystallinity of the grown crystal was confirmed to be good, and the exposed crystal face was perpendicular to the

[111] crystal orientation. The single crystal was cut into

[111] shaped wafers using diamond wire cutting.

[0049] The piezoelectric coefficient of TiCoSb single crystal

[111] cut wafers was measured using a ZJ-3AN piezoelectric measuring instrument from the Institute of Acoustics, Chinese Academy of Sciences. The piezoelectric coefficient measurement was performed in the atmosphere, with a force of 0.25 N at 110 Hz applied to the sample surface. To confirm whether the sample had effective piezoelectric characteristics in the vertical piezoelectric coefficient measurement mode, the piezoelectric coefficient was measured in ten different regions on the top and bottom surfaces of the sample, namely the center (A), upper left (B), upper right (C), lower left (D), and lower right (E). The surface regions on the upper and lower sides corresponded one-to-one, and the average value was calculated based on the measured vertical piezoelectric coefficient. The results are as follows: Figure 3 As shown. The piezoelectric coefficient of the sample prepared in this embodiment exhibits similar values ​​at different positions on the wafer, and the sign reverses as the wafer is rotated vertically. The absolute value of the piezoelectric coefficient of the sample prepared in this embodiment is 19 pC / N at 300 K.

[0050] The variable-temperature piezoelectric coefficient of TiCoSb single crystal

[111] cut wafers was measured using a Bailibo PMS1000 piezoelectric temperature spectrometer. The results are as follows: Figure 4 As shown. The piezoelectric coefficients of the samples prepared in this embodiment exhibit similar values ​​from 303K to 1173K, demonstrating the stability of their high-temperature piezoelectric properties.

[0051] Example 2

[0052] The raw materials were weighed according to a stoichiometric ratio of Zr:Ni:Sn = 1:1:10, and then placed into an alumina crucible in an argon-protected glove box. The alumina crucible was then sealed under vacuum in a quartz tube. The quartz tube was heated from room temperature to 1423 K over 12 hours, held at 1423 K for 48 hours, and then slowly cooled to 1023 K at a cooling rate of 2 K / h. Excess flux was removed using a centrifuge at 1500 rpm at 1023 K to obtain ZrNiSn single crystal samples.

[0053] The single crystal prepared in this embodiment was subjected to phase analysis using a Bruker D8 Venture single-crystal X-ray diffractometer equipped with Mo-palladium. The results are as follows: Figure 1 As shown, it was confirmed to be a semi-Hessler alloy structure, i.e., a cubic structure. The space group number is 216.

[0054] The orientation of the single crystal was determined using a Photonic Science Laue X-ray diffractometer, focusing on the exposed crystal planes of the preferentially grown single crystal. The results are as follows: Figure 2 As shown, the crystallinity of the grown crystal was confirmed to be good, and the exposed crystal face was perpendicular to the

[111] crystal orientation. The single crystal was cut into

[111] shaped wafers using diamond wire cutting.

[0055] The piezoelectric coefficient of a ZrNiSn single crystal

[111] cut wafer was measured using a ZJ-3AN piezoelectric measuring instrument from the Institute of Acoustics, Chinese Academy of Sciences. The results are as follows: Figure 3 As shown. The piezoelectric coefficient of the sample prepared in this embodiment exhibits similar values ​​at different positions on the wafer, and the sign reverses as the wafer is rotated vertically. The absolute value of the piezoelectric coefficient of the sample prepared in this embodiment is 22 pC / N at 300 K.

[0056] The variable-temperature piezoelectric coefficient of ZrNiSn single crystal

[111] cut wafers was measured using a Bailibo PMS1000 piezoelectric temperature spectrometer. The results are as follows: Figure 4 As shown. The piezoelectric coefficients of the samples prepared in this embodiment exhibit similar values ​​from 303K to 1173K, demonstrating the stability of their high-temperature piezoelectric properties.

[0057] Example 3

[0058] After weighing the raw materials according to the stoichiometric ratio of Ti:Ni:Sn = 1:1:10, they were placed into an alumina crucible in an argon-protected glove box. The alumina crucible was then sealed under vacuum in a quartz tube. The quartz tube was heated from room temperature to 1423 K over 12 hours, held at 1423 K for 48 hours, and then slowly cooled to 1023 K at a cooling rate of 2 K / h. Excess flux was removed using a centrifuge at 1500 rpm at 1023 K to obtain TiNiSn single crystal samples.

[0059] The single crystal prepared in this embodiment was subjected to phase analysis using a Bruker D8 Venture single-crystal X-ray diffractometer equipped with Mo-palladium. The results are as follows: Figure 1 As shown, it was confirmed to be a semi-Hessler alloy structure, i.e., a cubic structure. The space group number is 216.

[0060] The orientation of the single crystal was determined using a Photonic Science Laue X-ray diffractometer, focusing on the exposed crystal planes of the preferentially grown single crystal. The results are as follows: Figure 2 As shown, the crystallinity of the grown crystal was confirmed to be good, and the exposed crystal face was perpendicular to the

[111] crystal orientation. The single crystal was cut into

[111] shaped wafers using diamond wire cutting.

[0061] The piezoelectric coefficient of TiNiSn single crystal

[111] cut wafer was measured using a ZJ-3AN piezoelectric measuring instrument from the Institute of Acoustics, Chinese Academy of Sciences. The results are as follows: Figure 3 As shown. The piezoelectric coefficient of the sample prepared in this embodiment exhibits similar values ​​at different positions on the wafer, and the sign reverses as the wafer is rotated vertically. The absolute value of the piezoelectric coefficient of the sample prepared in this embodiment is 5 pC / N at 300 K.

[0062] The variable-temperature piezoelectric coefficient of TiNiSn single crystal

[111] cut wafers was measured using a Bailibo PMS1000 piezoelectric temperature spectrometer. The results are as follows: Figure 4 As shown in the figure, the piezoelectric coefficient of the sample prepared in this embodiment exhibits similar values ​​from 303K to 1173K, demonstrating the stability of its high-temperature piezoelectric properties. This is significantly higher than the high-temperature stability of existing piezoelectric materials, making it suitable for applications such as high-temperature piezoelectric sensors, including pressure detection in aero-engines and monitoring of boilers and heat exchangers.

[0063] Example 4

[0064] The raw materials were weighed according to the chemical dosage ratio Ti:Co:Sb = 1:1:1, placed in a copper tube crucible, and sealed with argon gas. A high-frequency current was applied to induce eddy currents in the raw materials, thereby melting them. After three repeated melting processes, a uniform ingot was obtained. The ingot was then crushed using a combination of mortar and pestle crushing and mechanical ball milling to obtain powder. Subsequently, the powder was sintered for 10 minutes at 1123 K and 65 MPa using a discharge plasma sintering method to obtain cylindrical bulk TiCoSb polycrystalline samples.

[0065] The phase composition of the sample prepared in this embodiment was analyzed using a PANalytical (Aries DY866) X-ray polycrystalline diffractometer (XRD) from the Netherlands. Figure 5 As shown, it was confirmed to be a semi-Hessler alloy structure, i.e., a cubic structure. The space group number is 216.

[0066] The piezoelectric coefficient of TiCoSb polycrystalline material was measured using a ZJ-3AN piezoelectric measuring instrument from the Institute of Acoustics, Chinese Academy of Sciences. The results are as follows: Figure 6 As shown. The piezoelectric coefficient of the sample prepared in this embodiment is not less than 8 pC / N at 300 K.

[0067] Example 5

[0068] The raw materials were weighed according to the chemical ratio Zr:Ni:Sn = 1:1:1, placed in a copper tube crucible, and sealed with argon gas. A high-frequency current was applied to induce eddy currents in the raw materials, thereby melting them. After three repeated melting processes, a uniform ingot was obtained. The ingot was then crushed using a combination of mortar and pestle crushing and mechanical ball milling to obtain powder. Subsequently, the powder was sintered for 10 minutes at 1123 K and 65 MPa using a discharge plasma sintering method to obtain cylindrical bulk ZrNiSn polycrystalline samples.

[0069] The phase composition of the sample prepared in this embodiment was analyzed using a PANalytical (Aries DY866) X-ray polycrystalline diffractometer (XRD) from the Netherlands. Figure 5 As shown, it was confirmed to be a semi-Hessler alloy structure, i.e., a cubic structure. The space group number is 216.

[0070] The piezoelectric coefficient of ZrNiSn polycrystalline material was measured using a ZJ-3AN piezoelectric measuring instrument from the Institute of Acoustics, Chinese Academy of Sciences. The results are as follows: Figure 6 As shown. The piezoelectric coefficient of the sample prepared in this embodiment is not less than 12 pC / N at 300 K.

[0071] Example 6

[0072] The raw materials were weighed according to the chemical dosage ratio Ti:Ni:Sn = 1:1:1, placed in a copper tube crucible, and sealed with argon gas. A high-frequency current was applied to induce eddy currents in the raw materials, thereby melting them. After three repeated melting processes, a uniform ingot was obtained. The ingot was then crushed using a combination of mortar and pestle crushing and mechanical ball milling to obtain powder. Subsequently, the powder was sintered for 10 minutes at 1123 K and 65 MPa using a discharge plasma sintering method to obtain cylindrical bulk TiNiSn polycrystalline samples.

[0073] The phase composition of the sample prepared in this embodiment was analyzed using a PANalytical (Aries DY866) X-ray polycrystalline diffractometer (XRD) from the Netherlands. Figure 5 As shown, it was confirmed to be a semi-Hessler alloy structure, i.e., a cubic structure. The space group number is 216.

[0074] The piezoelectric coefficient of TiNiSn polycrystalline material was measured using a ZJ-3AN piezoelectric measuring instrument from the Institute of Acoustics, Chinese Academy of Sciences. The results are as follows: Figure 6 As shown. The piezoelectric coefficient of the sample prepared in this embodiment is not less than 13 pC / N at 300 K.

[0075] Example 7

[0076] The raw materials were weighed according to the chemical ratio Hf:Ni:Sn = 1:1:1, placed in a copper tube crucible, and sealed with argon gas. A high-frequency current was applied to induce eddy currents in the raw materials, thereby melting them. After three repeated melting processes, a uniform ingot was obtained. The ingot was then crushed using a combination of mortar and pestle crushing and mechanical ball milling to obtain powder. Subsequently, the powder was sintered for 10 minutes at 1123 K and 65 MPa using a discharge plasma sintering method to obtain cylindrical bulk HfNiSn polycrystalline samples.

[0077] The phase composition of the sample prepared in this embodiment was analyzed using a PANalytical (Aries DY866) X-ray polycrystalline diffractometer (XRD) from the Netherlands. Figure 5 As shown, it was confirmed to be a semi-Hessler alloy structure, i.e., a cubic structure. The space group number is 216.

[0078] The piezoelectric coefficient of HfNiSn polycrystalline material was measured using a ZJ-3AN piezoelectric measuring instrument from the Institute of Acoustics, Chinese Academy of Sciences. The results are as follows: Figure 6 As shown. The piezoelectric coefficient of the sample prepared in this embodiment is not less than 10 pC / N at 300 K.

[0079] Example 8

[0080] The raw materials were weighed according to the chemical ratio Sc:Ni:Sb = 1:1:1, placed in a copper tube crucible, and sealed with argon gas. A high-frequency current was applied to induce eddy currents in the raw materials, thereby melting them. After three repeated melting processes, a uniform ingot was obtained. The ingot was then crushed using a combination of mortar and pestle crushing and mechanical ball milling to obtain powder. Subsequently, the powder was sintered for 10 minutes at 1123 K and 65 MPa using a discharge plasma sintering method to obtain cylindrical bulk ScNiSb polycrystalline samples.

[0081] The phase composition of the sample prepared in this embodiment was analyzed using a PANalytical (Aries DY866) X-ray polycrystalline diffractometer (XRD) from the Netherlands. Figure 5 As shown, it was confirmed to be a semi-Hessler alloy structure, i.e., a cubic structure. The space group number is 216.

[0082] The piezoelectric coefficient of the ScNiSb polycrystalline material was measured using a ZJ-3AN piezoelectric measuring instrument from the Institute of Acoustics, Chinese Academy of Sciences. The results are as follows: Figure 6 As shown. The piezoelectric coefficient of the sample prepared in this embodiment is not less than 8 pC / N at 300 K.

[0083] Example 9

[0084] The TiCoSb single crystal

[111] prepared in Example 1 was cut into wafers and processed to a size of 4×3×1mm. 3 A rectangular block of the required size was used to connect the sample to a copper electrode using EPO-TEK-H20E epoxy conductive silver paste, and cured at 373K for 1 hour. Insulating tape was then used to cover the surface of the copper electrode.

[0085] The open-circuit voltage of the piezoelectric sensor device prepared in this embodiment was measured using a Keithley 6514 electrometer, and the results are as follows. Figure 7 As shown. The open-circuit voltage of the piezoelectric sensor device prepared in this embodiment is not less than 0.15mV under a 22N press, not less than 0.05mV under a 15N press, and not less than 0.05mV under a 9N press.

[0086] The capacitive charging capability of the piezoelectric sensor device prepared in this embodiment was measured using a Keithley 6514 electrometer, and the results are as follows: Figure 8 As shown. The piezoelectric sensor device prepared in this embodiment accumulates a voltage of 2.55mV within 30s under a 15N pressure.

[0087] Example 10

[0088] The ZrNiSn polycrystalline material obtained in Example 5 was processed to a size of 2×2×0.5mm. 3 A rectangular block of the required size was used to connect the sample to a copper electrode using EPO-TEK-H20E epoxy conductive silver paste, and cured at 373K for 1 hour. Insulating tape was then used to cover the surface of the copper electrode.

[0089] The open-circuit voltage of the piezoelectric sensor device prepared in this embodiment was measured using a Keithley 6514 electrometer, and the results are as follows. Figure 9 As shown. The open-circuit voltage of the piezoelectric sensor device obtained in this embodiment is not less than 0.10mV under a 16N press.

[0090] Example 11

[0091] The TiNiSn polycrystalline material obtained in Example 6 was processed to a size of 2×2×0.5mm. 3 A rectangular block of the required size was used to connect the sample to a copper electrode using EPO-TEK-H20E epoxy conductive silver paste, and cured at 373K for 1 hour. Insulating tape was then used to cover the surface of the copper electrode.

[0092] The open-circuit voltage of the piezoelectric sensor device prepared in this embodiment was measured using a Keithley 6514 electrometer, and the results are as follows. Figure 9 As shown. The open-circuit voltage of the piezoelectric sensor device prepared in this embodiment is not less than 0.16mV under a 16N press.

[0093] Example 12

[0094] The HfNiSn polycrystalline material obtained in Example 7 was processed to a size of 2×2×0.5mm. 3 A rectangular block of the required size was used to connect the sample to a copper electrode using EPO-TEK-H20E epoxy conductive silver paste, and cured at 373K for 1 hour. Insulating tape was then used to cover the surface of the copper electrode.

[0095] The open-circuit voltage of the piezoelectric sensor device prepared in this embodiment was measured using a Keithley 6514 electrometer, and the results are as follows. Figure 9 As shown. The open-circuit voltage of the piezoelectric sensor device prepared in this embodiment is not less than 0.12mV under a 16N press.

[0096] Example 13

[0097] The ScNiSb polycrystalline material obtained in Example 8 was processed to a size of 2×2×0.5mm.3 A rectangular block of the required size was used to connect the sample to a copper electrode using EPO-TEK-H20E epoxy conductive silver paste, and cured at 373K for 1 hour. Insulating tape was then used to cover the surface of the copper electrode.

[0098] The open-circuit voltage of the piezoelectric sensor device prepared in this embodiment was measured using a Keithley 6514 electrometer, and the results are as follows. Figure 9 As shown. The open-circuit voltage of the piezoelectric sensor device prepared in this embodiment is not less than 0.06mV under a 16N press.

[0099] Piezoelectric performance analysis:

[0100] The single crystal and polycrystalline semi-Hersler alloy piezoelectric materials prepared in Examples 1-8 all showed a piezoelectric coefficient of not less than 5 pC / N at room temperature, which is comparable to the piezoelectric coefficient of quartz crystal at room temperature of 2.3 pC / N. The semi-Hersler alloy piezoelectric materials prepared in this invention have performance comparable to traditional piezoelectric crystals.

[0101] The single crystals of the semi-Hessler alloy piezoelectric materials prepared in Examples 1-3 maintain a stable piezoelectric coefficient from room temperature to 1173 K, which is higher than the Curie temperature of commercial lead zirconate titanate piezoelectric ceramics (approximately 600 K) and quartz crystals (850 K). The semi-Hessler alloy piezoelectric materials prepared in this invention demonstrate potential for high-temperature piezoelectric applications.

[0102] The semi-Hessler alloy piezoelectric sensor devices prepared in Examples 9-13 can produce observable open-circuit voltage responses in the sub-mV range within the range of normal human body pressure, with no significant delay. The semi-Hessler alloy piezoelectric devices prepared in this invention demonstrate the potential for piezoelectric sensing applications and can be used to prepare electronic devices such as sound wave generators, automotive collision sensors, pressure sensors, vibration power generation devices, and medical equipment.

Claims

1. Use of a semi-Heusler alloy as a piezoelectric material, characterized in that The chemical formula of the semi-Hessler alloy is XYZ, where X = any one or more rare earth elements in any proportion, such as Ti, Zr, Hf, V, Nb, Ta, Y = Fe, Co, or Ni, and Z = Sn, Sb, or Bi.

2. Use of a half Heusler alloy according to claim 1 as piezoelectric material, characterized in that The chemical formula of the semi-Hessler alloy is XYZ, wherein X = any one or more of Ti, Zr, Hf, V, Nb, Ta, Sc, Y, Dy, Er, Tm, and Lu in any proportion, Y = Fe, Co, or Ni, and Z = Sn, Sb, or Bi. Preferably, the chemical formula of the semi-Hessler alloy is XYZ, wherein X = any one or more of Ti, Zr, Hf, and Sc in any proportion, Y = Co or Ni, and Z = Sn or Sb; More preferably, the semi-Hessler alloy is any one of TiNiSn, ZrNiSn, HfNiSn, TiCoSb, and ScNiSb.

3. Use of a half-Heusler alloy according to claim 1 as piezoelectric material, characterized in that In the semi-Hessler alloy, the sum of the outermost electrons of the X, Y, and Z atoms satisfies the 18-electron rule, thus exhibiting a narrow bandgap semiconductor material.

4. The application of the semi-Hessler alloy according to claim 1 as a piezoelectric material, characterized in that, The semi-Hessler alloy is a single crystal or a polycrystalline alloy.

5. The application of a type of semi-Hessler alloy in high-temperature piezoelectric sensing, characterized in that, Includes the semi-Hessler alloy as described in claim 1, wherein the stable operating temperature of the semi-Hessler alloy is 1-1500K.

6. A method for testing the piezoelectric coefficient of a class of semi-Hessler alloy single crystals, characterized in that, The chemical formula of the semi-Hersler alloy is XYZ, wherein X = any one or more rare earth elements in any proportion of solid solution, Y = Fe or Co or Ni, and Z = Sn or Sb or Bi; the piezoelectric coefficient of the semi-Hersler alloy is measured by [111] cut wafer.

7. A piezoelectric device made of a semi-Hessler alloy, characterized in that, Includes the semi-Hessler alloy and electrode as described in claim 1.

8. The piezoelectric device of semi-Hessler alloy according to claim 7, characterized in that, The piezoelectric device includes any one or more of the following: piezoelectric sensor, piezoelectric vibration energy harvester, and piezoelectric self-powered system.

9. The piezoelectric device of semi-Hessler alloy according to claim 8, characterized in that, Under normal human body pressure, the absolute value of the voltage response obtained by the sensor is above 0.05mV; under normal human body pressure, the piezoelectric vibration energy harvester accumulates a voltage above 2mV within 30s.

10. An electronic device, characterized in that, Includes the piezoelectric device as described in claim 7.

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