A piezoelectric ceramic material, its preparation method and application

Abstract

This invention provides a piezoelectric ceramic material, its preparation method, and its application, belonging to the field of electronic ceramics technology. The piezoelectric ceramic material is represented by the following stoichiometric formula: Pb(Zr) 0.52 Ti 0.48 ) (1‑x) Ta x O3-ywt%Ca (1‑2z) M z Ce z Bi4Ti4O 15 Wherein, M is at least one of Li, Na, and K, 0.02≤x≤0.04, 0.4≤y≤1.2, and 0.015≤z≤0.07. This invention also includes a method for preparing piezoelectric ceramic materials and their application in the preparation of intermediate-temperature piezoelectric accelerometers. The piezoelectric ceramic material of this invention has a high Curie point, high piezoelectric performance, high resistivity, and excellent temperature flatness response performance. This material, as a sensing core, can be used to prepare wide-temperature, wide-frequency, and high-sensitivity piezoelectric accelerometers.

Description

Technical Field

[0001] This invention belongs to the field of electronic ceramics technology, specifically relating to a piezoelectric ceramic material, its preparation method, and its application. Background Technology

[0002] Piezoelectric ceramics are an important class of functional inorganic non-metallic materials. Due to their unique piezoelectric effect, they are often used as sensitive elements for electromechanical conversion. Various devices made from piezoelectric ceramics, such as ceramic actuators, resonators, filters, gyroscopes, and accelerometers, are widely used in aerospace, automotive, and nuclear power industries. In particular, piezoelectric accelerometers, due to their low production cost and high reliability, are widely used for vibration monitoring in various types of aircraft, automotive engines, and gas turbines, showing broad application prospects. The performance of a piezoelectric accelerometer mainly depends on the piezoelectric core; the strength, stability, and high-temperature performance of the piezoelectric material, among other core parameters, determine the quality and application range of the piezoelectric accelerometer.

[0003] Among the many types of piezoelectric accelerometers, medium-temperature (typically below 260℃) piezoelectric accelerometers used in civilian fields such as nuclear power and automobiles have a broad market potential. The sensing element used in medium-temperature piezoelectric accelerometers is usually made of lead zirconate titanate (PZT) ceramic material with high piezoelectric activity, and its Curie temperature is usually below 380℃. PZT ceramic materials have a typical perovskite structure, with grains formed by repeated stacking of oxygen octahedra along their respective crystal axes. This results in typical spherical grains without obvious directionality. This crystal structure makes the electric domains of PZT ceramics easy to deflect, resulting in good piezoelectricity, but also makes its mechanical properties relatively "soft." Under large external stress, pores or microcracks inside the ceramic easily propagate along the grain boundaries, leading to irreversible deformation on a macroscopic scale. The electric domains deviate from their original polarization direction (the direction in which the sensing element is used). This manifests as a low charge conversion efficiency when pure PZT piezoelectric ceramics are used as sensing elements in sensors. On the other hand, the dielectric constant of pure PZT ceramics changes drastically when subjected to temperature changes from negative to high (-25 to 260°C), ultimately affecting the temperature stability of the PZT material. This is extremely detrimental to the temperature drift performance of piezoelectric accelerometers. Current technologies often modify piezoelectric materials by substituting at the A and B sites or introducing compounds such as Sm₂O₃ or Nb₂O₅ to prepare sensitive elements. However, after assembling the sensor, the temperature deviation of the sensitivity can reach 30%, making commercial application difficult. How to prepare a piezoelectric material with high strength, stable performance, and good temperature drift characteristics remains one of the unsolved problems. Summary of the Invention

[0004] The problem to be solved by this invention is to provide a piezoelectric ceramic material, its preparation method and application, so as to solve the problems of poor temperature stability, poor temperature drift performance and unstable piezoelectric performance of piezoelectric ceramic materials.

[0005] The technical solution adopted to solve its technical problem is to provide a piezoelectric ceramic material, which is represented by the following stoichiometric formula: Pb(Zr) 0.52 Ti 0.48 ) (1-x) Ta x O3-ywt%Ca (1-2z) M z Ce z Bi4Ti4O 15 Where M is at least one of Li, Na and K, 0.02≤x≤0.04, 0.4≤y≤1.2 and 0.015≤z≤0.07.

[0006] The beneficial effects of the above-mentioned technical solution of this invention are as follows: The piezoelectric ceramic material of this invention uses Ta to substitute for the B-site of PZT matrix ceramic and introduces a second phase after A-site substitution, which changes the crystal structure of the existing PZT ceramic at the microscopic level. The lamellar grains of the piezoelectric ceramic material of this invention are interspersed on the grain boundaries of spherical grains, forming a certain pinning effect, which can effectively prevent crack propagation and harden the PZT matrix. When used to prepare piezoelectric accelerometers, the charge sensitivity conversion efficiency is significantly improved. At the same time, the introduction of the second phase can also suppress the degree of crystal structure transformation of PZT matrix ceramics when subjected to temperature changes, so that the electrical properties of the ceramic have better temperature flatness response. The piezoelectric accelerometer prepared in this way can be used for a long time in the medium temperature range (-25 to 260℃) and also has excellent piezoelectricity and temperature drift performance.

[0007] This invention also provides a method for preparing the above-mentioned piezoelectric ceramic material, comprising the following steps:

[0008] (1) PbO, ZrO2, Ta2O5 and TiO2 are stoichiometrically calculated according to the general formula Pb(ZrO2) = ... 0.52 Ti 0.48 ) (1-x) Ta x O3 was prepared, and after ball milling, drying and grinding and pre-calcination, pre-calcined raw material A was obtained;

[0009] (2) According to the stoichiometric formula of CaCO3, Bi2O3, CeO2, TiO2 and the carbonate of M, Ca (1-2z) M z Ce z Bi4Ti4O 15 The mixture is prepared, ball-milled, dried, ground, and pre-calcined to obtain pre-calcined raw material B;

[0010] (3) Pre-calcined raw material A and pre-calcined raw material B are mixed according to the mass ratio of the stoichiometric formula and then ball-milled to obtain a mixed slurry;

[0011] (4) Process the mixed slurry to make ceramic sheets;

[0012] (5) Polish the surface of the ceramic sheet and print electrodes. After firing, the ceramic sheet is polarized by an electric field and aged to obtain the piezoelectric ceramic material.

[0013] Preferably, the ball milling method in steps (1), (2) and (3) is planetary ball milling, and the rotation speed is 250 to 350 rad / min; the ball milling time in steps (1) and (2) is 3 to 5 hours, and the ball milling time in step (3) is 5 to 7 hours.

[0014] Preferably, the heating rate of the preheating in steps (1) and (2) is 2-4℃ / min, the temperature is 800-900℃, and the time is 1.5-2.5h.

[0015] Preferably, the process of making ceramic sheets from the mixed slurry in step (4) includes the following steps: after drying the mixed slurry, adding a polyvinyl alcohol solution with a mass concentration of 6-12% for pelletizing, drying and sieving, pressing it into a ceramic green body under 6-10 MPa, and then sintering the ceramic green body after removing the binder to obtain ceramic sheets.

[0016] More preferably, the sieve mesh size is 40 to 50 mesh.

[0017] More preferably, the debinding process includes the following steps: placing the ceramic green body in a debinding furnace and heating it to 550-650°C at a rate of 0.5-1.5°C / min, then allowing it to cool naturally to room temperature; the sintering process involves a heating rate of 2-4°C / min, a temperature of 1190-1250°C, and a time of 1.5-2.5 hours.

[0018] Preferably, the electrode in step (5) is a silver electrode; the heating rate during firing is 8-12℃ / min, the temperature is 500-600℃, and the time is 8-12min.

[0019] Preferably, the electric field polarization in step (5) includes the following steps: placing the fired ceramic sheet in silicone oil at 110-130°C, applying a DC electric field of 2.8-3.5kV to both ends of the sheet and holding the voltage for 5-10 minutes.

[0020] Preferably, the aging temperature is 270–290℃ and the time is 45–50h.

[0021] The present invention also provides the application of the above-mentioned piezoelectric ceramic material in the preparation of a medium-temperature piezoelectric accelerometer.

[0022] The present invention has the following beneficial effects:

[0023] (1) The piezoelectric ceramic material prepared by the present invention has good stability in the medium temperature range (-25 to 260℃) and the sensitivity temperature deviation is less than 5%. At the same time, the preparation method of the piezoelectric ceramic material of the present invention is simple, the material is readily available, and it is suitable for large-scale industrial production.

[0024] (2) The piezoelectric ceramic material prepared by the present invention has good uniformity of piezoelectric coefficient, and when used to prepare a medium-temperature piezoelectric accelerometer, it has wide temperature range, wide frequency range and excellent temperature flatness response. Attached Figure Description

[0025] Figure 1 These are microscopic images of the piezoelectric ceramic material prepared in Example 1;

[0026] Figure 2 These are microscopic images of PZT ceramic materials.

[0027] Figure 3 This is a microscopic morphology diagram of CBT ceramic material crystals. Detailed Implementation

[0028] The features and performance of the present invention will be further described in detail below with reference to embodiments.

[0029] Example 1

[0030] A piezoelectric ceramic material with the composition Pb(Zr) 0.52 Ti 0.48 ) 0.97 Ta 0.03 O3-0.8wt% Ca 0.9 Li 0.05 Ce 0.05 Bi4Ti4O 15 .

[0031] The piezoelectric ceramic material in this embodiment is prepared through the following steps:

[0032] (1) Analytical grade PbO, ZrO2, Ta2O5, and chemically pure TiO2 were classified according to the final product being Pb(ZrO2)O2. 0.52 Ti 0.48 ) 0.97 Ta 0.03 O3 was weighed, mixed evenly, and then placed into a polytetrafluoroethylene ball mill jar. It was then ball-milled at a speed of 300 rad / min for 4 hours using a planetary ball mill. After drying in a drying oven, it was taken out and ground evenly again. It was then placed into a crucible and compacted. The crucible was covered and placed in a high-temperature furnace. The temperature was increased to 875°C at a heating rate of 3°C / min and held for 2 hours to obtain pre-calcined raw material A.

[0033] (2) Analytical grade CaCO3, Bi2O3, CeO2, TiO2, and Li2CO3 were processed according to the final product being Ca...0.9 Li 0.05 Ce 0.05 Bi4Ti4O 15 Weigh the mixture, mix it thoroughly, and then put it into a polytetrafluoroethylene ball mill jar. Use a planetary ball mill to mill the mixture at a speed of 300 rad / min for 4 hours. Then dry it in a drying oven, take it out, grind it evenly again, put it into a crucible, compact it, cover the crucible, and place it in a high-temperature furnace. Heat it to 850℃ at a heating rate of 3℃ / min and hold it for 2 hours to obtain pre-calcined raw material B.

[0034] (3) Pre-calcined raw material A and pre-calcined raw material B are processed according to the final product being Pb(Zr). 0.52 Ti 0.48 ) 0.97 Ta 0.03 O3-0.8wt% Ca 0.9 Li 0.05 Ce 0.05 Bi4Ti4O 15 Weigh the mixture, prepare it, and put it into a polytetrafluoroethylene ball mill jar. Use a planetary ball mill to mill the mixture at a speed of 300 rad / min for 6 hours to obtain a mixed slurry.

[0035] (4) Place the mixed slurry in a drying oven to dry it, then pour it into an alumina mortar, add a 6% polyvinyl alcohol solution to granulate it, and after granulation, place it in a drying oven to dry it and pass it through a 45-mesh sieve. Then press it into Φ10 rings with a pressure of 8MPa to obtain ceramic green bodies.

[0036] (5) Place the ceramic green body in a debinding furnace, heat it to 600°C at a rate of 1°C / min, and then let it cool naturally to room temperature. Place the debinded ceramic green body in a high-temperature furnace, heat it to 1200°C at a rate of 3°C / min, keep it at that temperature for 2 hours, and then let it cool naturally to room temperature to obtain ceramic sheets.

[0037] (6) Polish the ceramic sheet to 1 mm thickness using a double-sided grinder, then print silver electrodes on the surface of the ceramic sheet using screen printing. After drying, place it in a silver firing furnace and heat it to 550°C at a rate of 10°C / min and hold it for 10 min to obtain a ceramic sheet with electrodes.

[0038] (7) Place the electrode ceramic sheet in silicone oil at 120℃, apply a DC electric field of 3.5kV to both ends of the electrode ceramic sheet and hold the voltage for 10min to obtain polarized piezoelectric ceramic.

[0039] (8) The polarized piezoelectric ceramic is placed in a high-temperature furnace and kept at 280°C for 48 hours. After cooling, the piezoelectric ceramic material is obtained.

[0040] In this embodiment, the piezoelectric ceramic material, after being labeled with electrodes, can be used as a sensitive element for assembling a medium-temperature piezoelectric accelerometer.

[0041] Example 2

[0042] A piezoelectric ceramic material with the composition Pb(Zr) 0.52 Ti 0.48 ) 0.96 Ta 0.04 O3-0.6wt% Ca 0.88 Na 0.06 Ce 0.06 Bi4Ti4O 15 .

[0043] The piezoelectric ceramic material in this embodiment is prepared through the following steps:

[0044] (1) Analytical grade PbO, ZrO2, Ta2O5, and chemically pure TiO2 were classified according to the final product being Pb(ZrO2)O2. 0.52 Ti 0.48 ) 0.96 Ta 0.04 O3 was weighed, mixed evenly, and then placed into a polytetrafluoroethylene ball mill jar. It was then ball-milled at a speed of 300 rad / min for 4 hours using a planetary ball mill. After drying in a drying oven, it was taken out and ground evenly again. It was then placed into a crucible and compacted. The crucible was covered and placed in a high-temperature furnace. The temperature was increased to 875°C at a heating rate of 3°C / min and held for 2 hours to obtain pre-calcined raw material A.

[0045] (2) Analytical grade CaCO3, Bi2O3, CeO2, TiO2, and Na2CO3 were processed according to the final product being Ca... 0.88 Na 0.06 Ce 0.06 Bi4Ti4O 15 Weigh the mixture, mix it thoroughly, and then put it into a polytetrafluoroethylene ball mill jar. Use a planetary ball mill to mill the mixture at a speed of 300 rad / min for 4 hours. Then dry it in a drying oven, take it out, grind it evenly again, put it into a crucible, compact it, cover the crucible, and place it in a high-temperature furnace. Heat it to 850℃ at a heating rate of 3℃ / min and hold it for 2 hours to obtain pre-calcined raw material B.

[0046] (3) Pre-calcined raw material A and pre-calcined raw material B are processed according to the final product being Pb(Zr). 0.52 Ti 0.48 ) 0.96 Ta 0.04 O3-0.6wt% Ca 0.88 Na 0.06 Ce 0.06 Bi4Ti4O 15Weigh the mixture, prepare it, and put it into a polytetrafluoroethylene ball mill jar. Use a planetary ball mill to mill the mixture at a speed of 300 rad / min for 6 hours to obtain a mixed slurry.

[0047] (4) Place the mixed slurry in a drying oven to dry it, then pour it into an alumina mortar, add a 6% polyvinyl alcohol solution to granulate it, and after granulation, place it in a drying oven to dry it and pass it through a 45-mesh sieve. Then press it into Φ10 rings with a pressure of 8MPa to obtain ceramic green bodies.

[0048] (5) Place the ceramic green body in a debinding furnace, heat it to 600°C at a rate of 1°C / min, and then let it cool naturally to room temperature. Place the debinded ceramic green body in a high-temperature furnace, heat it to 1210°C at a rate of 3°C / min, keep it at that temperature for 2 hours, and then let it cool naturally to room temperature to obtain ceramic sheets.

[0049] (6) Polish the ceramic sheet to 1 mm thickness using a double-sided grinder, then print silver electrodes on the surface of the ceramic sheet using screen printing. After drying, place it in a silver firing furnace and heat it to 550°C at a rate of 10°C / min and hold it for 10 min to obtain a ceramic sheet with electrodes.

[0050] (7) Place the electrode ceramic sheet in silicone oil at 120℃, apply a DC electric field of 3.0kV to both ends of the electrode ceramic sheet and hold the voltage for 10min to obtain polarized piezoelectric ceramic.

[0051] (8) The polarized piezoelectric ceramic is placed in a high-temperature furnace and kept at 280°C for 48 hours. After cooling, the piezoelectric ceramic material is obtained.

[0052] In this embodiment, the piezoelectric ceramic material, after being labeled with electrodes, can be used as a sensitive element for assembling a medium-temperature piezoelectric accelerometer.

[0053] Example 3

[0054] A piezoelectric ceramic material with the composition Pb(Zr) 0.52 Ti 0.48 ) 0.98 Ta 0.02 O3-1.0wt% Ca 0.9 Li 0.015 Na 0.015 Ce 0.07 Bi4Ti4O 15 .

[0055] The piezoelectric ceramic material in this embodiment is prepared through the following steps:

[0056] (1) Analytical grade PbO, ZrO2, Ta2O5, and chemically pure TiO2 were classified according to the final product being Pb(ZrO2)O2. 0.52 Ti 0.48) 0.98 Ta 0.02 O3 was weighed, mixed evenly, and then placed into a polytetrafluoroethylene ball mill jar. It was then ball-milled at a speed of 300 rad / min for 4 hours using a planetary ball mill. After drying in a drying oven, it was taken out and ground evenly again. It was then placed into a crucible and compacted. The crucible was covered and placed in a high-temperature furnace. The temperature was increased to 875°C at a heating rate of 3°C / min and held for 2 hours to obtain pre-calcined raw material A.

[0057] (2) Analytical grade CaCO3, Bi2O3, CeO2, TiO2, Na2CO3, and Li2CO3 were classified according to their final product as Ca... 0.9 Li 0.015 Na 0.01 5Ce 0.07 Bi4Ti4O 15 Weigh the mixture, mix it thoroughly, and then put it into a polytetrafluoroethylene ball mill jar. Use a planetary ball mill to mill the mixture at a speed of 300 rad / min for 4 hours. Then dry it in a drying oven, take it out, grind it evenly again, put it into a crucible, compact it, cover the crucible, and place it in a high-temperature furnace. Heat it to 850℃ at a heating rate of 3℃ / min and hold it for 2 hours to obtain pre-calcined raw material B.

[0058] (3) Pre-calcined raw material A and pre-calcined raw material B are processed according to the final product being Pb(Zr). 0.52 Ti 0.48 ) 0.98 Ta 0.02 O3-1.0wt% Ca 0. 9Li 0.015 Na 0.015 Ce 0.07 Bi4Ti4O 15 Weigh the mixture, prepare it, and put it into a polytetrafluoroethylene ball mill jar. Use a planetary ball mill to mill the mixture at a speed of 300 rad / min for 6 hours to obtain a mixed slurry.

[0059] (4) Place the mixed slurry in a drying oven to dry it, then pour it into an alumina mortar, add a 6% polyvinyl alcohol solution to granulate it, and after granulation, place it in a drying oven to dry it and pass it through a 45-mesh sieve. Then press it into Φ10 rings with a pressure of 8MPa to obtain ceramic green bodies.

[0060] (5) Place the ceramic green body in a debinding furnace, heat it to 600°C at a rate of 1°C / min, and then let it cool naturally to room temperature. Place the debinded ceramic green body in a high-temperature furnace, heat it to 1190°C at a rate of 3°C / min, keep it at that temperature for 2 hours, and then let it cool naturally to room temperature to obtain ceramic sheets.

[0061] (6) Polish the ceramic sheet to 1 mm thickness using a double-sided grinder, then print silver electrodes on the surface of the ceramic sheet using screen printing. After drying, place it in a silver firing furnace and heat it to 550°C at a rate of 10°C / min and hold it for 10 min to obtain a ceramic sheet with electrodes.

[0062] (7) Place the electrode ceramic sheet in silicone oil at 120°C, apply a DC electric field of 2.8kV to both ends of the electrode ceramic sheet and hold the voltage for 10min to obtain polarized piezoelectric ceramic.

[0063] (8) The polarized piezoelectric ceramic is placed in a high-temperature furnace and kept at 280°C for 48 hours. After cooling, the piezoelectric ceramic material is obtained.

[0064] In this embodiment, the piezoelectric ceramic material, after being labeled with electrodes, can be used as a sensitive element for assembling a medium-temperature piezoelectric accelerometer.

[0065] Example 4

[0066] A piezoelectric ceramic material with the composition Pb(Zr) 0.52 Ti 0.48 ) 0.97 Ta 0.03 O3-0.4wt% Ca 0.92 K 0.04 Ce 0.04 Bi4Ti4O 15 .

[0067] The piezoelectric ceramic material in this embodiment is prepared through the following steps:

[0068] (1) Analytical grade PbO, ZrO2, Ta2O5, and chemically pure TiO2 were classified according to the final product being Pb(ZrO2)O2. 0.52 Ti 0.48 ) 0.97 Ta 0.03 O3 was weighed, mixed evenly, and then placed into a polytetrafluoroethylene ball mill jar. It was ball milled at a speed of 250 rad / min for 5 hours using planetary ball milling. After that, it was dried in a drying oven, taken out and ground evenly again. It was then placed into a crucible and compacted. The crucible was covered and placed in a high-temperature furnace. The temperature was increased to 800℃ at a heating rate of 2℃ / min and held for 1.5 hours to obtain pre-calcined raw material A.

[0069] (2) Analytical grade CaCO3, Bi2O3, CeO2, TiO2, and K2CO3 were processed according to the final product being Ca... 0.92 K 0.04 Ce 0.04 Bi4Ti4O 15Weigh the mixture, mix it thoroughly, and then place it in a polytetrafluoroethylene ball mill jar. Use a planetary ball mill to mill the mixture at a speed of 250 rad / min for 5 hours. Then, dry the mixture in a drying oven, remove it, grind it thoroughly again, pack it into a crucible, compact it, cover the crucible, and place it in a high-temperature furnace. Heat the mixture to 850°C at a heating rate of 2°C / min and hold it at that temperature for 2.5 hours to obtain pre-calcined raw material B.

[0070] (3) Pre-calcined raw material A and pre-calcined raw material B are processed according to the final product being Pb(Zr). 0.52 Ti 0.48 ) 0.97 Ta 0.03 O3-0.4wt% Ca 0.92 K 0.04 Ce 0.04 Bi4Ti4O 15 Weigh the mixture, prepare it, and put it into a polytetrafluoroethylene ball mill jar. Use a planetary ball mill to mill the mixture at a speed of 250 rad / min for 7 hours to obtain a mixed slurry.

[0071] (4) Place the mixed slurry in a drying oven to dry it, then pour it into an alumina mortar, add a polyvinyl alcohol solution with a mass concentration of 8% for pelletizing, after pelletizing, place it in a drying oven to dry it and pass it through a 40-mesh sieve, and then press it into Φ10 rings with a pressure of 6MPa to obtain ceramic green bodies.

[0072] (5) Place the ceramic green body in a debinding furnace, heat it to 550°C at a rate of 0.5°C / min, and then let it cool naturally to room temperature. Place the debinding ceramic green body in a high-temperature furnace, heat it to 1190°C at a rate of 2°C / min, keep it at that temperature for 2.5 hours, and then let it cool naturally to room temperature with the furnace to obtain ceramic sheets.

[0073] (6) Polish the ceramic sheet to 1 mm thickness using a double-sided grinder, then print silver electrodes on the surface of the ceramic sheet using screen printing. After drying, place it in a silver firing furnace and heat it to 500°C at a rate of 8°C / min and hold it for 12 min to obtain a ceramic sheet with electrodes.

[0074] (7) Place the electrode ceramic sheet in silicone oil at 110℃, apply a DC electric field of 2.8kV to both ends of the electrode ceramic sheet and hold the voltage for 10min to obtain polarized piezoelectric ceramic.

[0075] (8) The polarized piezoelectric ceramic is placed in a high-temperature furnace and kept at 270°C for 50 hours. After cooling, the piezoelectric ceramic material is obtained.

[0076] In this embodiment, the piezoelectric ceramic material, after being labeled with electrodes, can be used as a sensitive element for assembling a medium-temperature piezoelectric accelerometer.

[0077] Example 5

[0078] A piezoelectric ceramic material with the composition Pb(Zr) 0.52 Ti 0.48 ) 0.97 Ta 0.03 O3-1.2wt% Ca 0.92 Li 0.02 K 0.02 Ce 0.04 Bi4Ti4O 15 .

[0079] The piezoelectric ceramic material in this embodiment is prepared through the following steps:

[0080] (1) Analytical grade PbO, ZrO2, Ta2O5, and chemically pure TiO2 were classified according to the final product being Pb(ZrO2)O2. 0.52 Ti 0.48 ) 0.97 Ta 0.03 O3 was weighed, mixed evenly, and then placed into a polytetrafluoroethylene ball mill jar. It was ball milled at a speed of 350 rad / min for 3 hours using planetary ball milling. After that, it was dried in a drying oven, taken out and ground evenly again. It was then placed into a crucible and compacted. The crucible was covered and placed in a high-temperature furnace. The temperature was increased to 900℃ at a heating rate of 4℃ / min and held for 2.5 hours to obtain pre-calcined raw material A.

[0081] (2) Analytical grade CaCO3, Bi2O3, CeO2, TiO2, Li2CO3, and K2CO3 were classified according to their final product as Ca... 0.92 Li 0.02 K 0.02 Ce 0.04 Bi4Ti4O 15 Weigh the mixture, mix it thoroughly, and then place it in a polytetrafluoroethylene ball mill jar. Use a planetary ball mill to mill the mixture at a speed of 350 rad / min for 3 hours. After milling, place it in a drying oven to dry it, take it out, grind it evenly again, pack it into a crucible, compact it, cover the crucible, and place it in a high-temperature furnace. Heat the crucible to 800℃ at a heating rate of 4℃ / min and hold it for 1.5 hours to obtain pre-calcined raw material B.

[0082] (3) Pre-calcined raw material A and pre-calcined raw material B are processed according to the final product being Pb(Zr). 0.52 Ti 0.48 ) 0.97 Ta 0.03 O3-1.2wt% Ca 0.92 Li 0.02 K 0.02 Ce 0.04 Bi4Ti4O 15 Weigh the mixture, prepare it, and put it into a polytetrafluoroethylene ball mill jar. Use a planetary ball mill to mill the mixture at a speed of 350 rad / min for 5 hours to obtain a mixed slurry.

[0083] (4) Place the mixed slurry in a drying oven to dry it, then pour it into an alumina mortar, add a 7% polyvinyl alcohol solution to granulate it, and after granulation, place it in a drying oven to dry it and pass it through a 50-mesh sieve. Then press it into Φ10 rings with a pressure of 10MPa to obtain ceramic green bodies.

[0084] (5) Place the ceramic green body in a debinding furnace, heat it to 650°C at a rate of 1.5°C / min, and then let it cool naturally to room temperature. Place the debinded ceramic green body in a high-temperature furnace, heat it to 1250°C at a rate of 4°C / min, keep it at that temperature for 1.5 hours, and then let it cool naturally to room temperature with the furnace to obtain ceramic sheets.

[0085] (6) Polish the ceramic sheet to 1 mm thickness using a double-sided grinder, then print silver electrodes on the surface of the ceramic sheet using screen printing. After drying, place it in a silver firing furnace and heat it to 600℃ at a rate of 12℃ / min and hold it for 8 min to obtain a ceramic sheet with electrodes.

[0086] (7) Place the electrode ceramic sheet in silicone oil at 130℃, apply a DC electric field of 3.0kV to both ends of the electrode ceramic sheet and hold the voltage for 5min to obtain polarized piezoelectric ceramic.

[0087] (8) The polarized piezoelectric ceramic is placed in a high-temperature furnace and kept at 290°C for 45 hours. After cooling, the piezoelectric ceramic material is obtained.

[0088] In this embodiment, the piezoelectric ceramic material, after being labeled with electrodes, can be used as a sensitive element for assembling a medium-temperature piezoelectric accelerometer.

[0089] Experimental Example

[0090] 1. The crystal microstructures of the piezoelectric ceramic material, PZT ceramic material, and CBT ceramic material prepared in Example 1 are shown below. Figures 1-3 As shown. From Figures 1-3 As can be seen, compared with PZT ceramic materials and CBT ceramic materials, the piezoelectric ceramic material crystal prepared by this invention has interpenetrating plate-like grains and spherical grains, which can produce a certain "pinning" effect on the expansion of its grain boundaries, thus preventing the expansion of cracks. Using it to prepare piezoelectric accelerometers can improve its charge-sensitive conversion efficiency.

[0091] 2. The room temperature piezoelectric constant d of the piezoelectric ceramic materials and PZT ceramic materials in Examples 1-3. 33 High temperature resistance R 260℃ Curie temperature T C and depolarization temperature T d The measurement was performed. Where d... 33 Using quasi-static d33 The test was conducted at room temperature, with a test frequency of 110Hz and a dynamic force of 0.25N; the high-temperature resistance R... 260℃ The high-temperature resistance testing system was used, with the temperature increased to 260℃ at a rate of 3℃ / min and held for 10 minutes before testing; Curie temperature T... C The test was conducted using a high-temperature dielectric testing system, with the temperature continuously increased to 500℃ at a rate of 3℃ / min, and held at 500℃ for 10 minutes to complete the test; the depolarization temperature T d The test uses quasi-static d 33 The testing was conducted using an instrument. The polarized ceramic was placed in an aging furnace and heated to 260℃, 270℃, 280℃, 290℃, 300℃, 310℃, 320℃, 330℃, 340℃, and 350℃ respectively at a heating rate of 3℃ / min, and held for 2 hours each time. Then it was cooled to room temperature for further testing. 33 Test, take d 33 The aging temperature at which a significant decrease begins is the depolarization temperature (d). 33 (Attenuation of approximately 20%). The results are shown in Table 1.

[0092] Table 1 Electrical properties of piezoelectric ceramic materials and PZT ceramic materials in Examples 1-3

[0093] <![CDATA[d 33 (pC / N)]]> <![CDATA[R 260℃ (Oh)]]> <![CDATA[T C (℃)]]> <![CDATA[T d (℃)]]> Example 1 430 <![CDATA[6.2×10 9 ]]> 370 330 Example 2 425 <![CDATA[7.0×10 9 ]]> 362 320 Example 3 410 <![CDATA[5.3×10 9 ]]> 364 330 PZT ceramic materials 407 <![CDATA[1.0×10 10 ]]> 360 310

[0094] 3. The piezoelectric ceramic materials and PZT ceramic materials of Examples 1 to 3 were assembled into the piezoelectric accelerometer, and the sensitivity-temperature test was carried out by the high and low temperature vibration test system. The results are shown in Table 2.

[0095] Table 2. Results of piezoelectric accelerometer sensitivity-temperature test

[0096]

[0097]

[0098] Note: The test data for sensitivity deviation in Table 2 are based on the accelerometer test values ​​at 25℃.

[0099] As can be seen from Tables 1 and 2, this invention, through modification of the crystal structure of pure PZT ceramic material, yields a new piezoelectric material with significantly improved high-temperature stability. The sensitivity temperature deviation of the materials in the examples is less than 5% (-25 to 260℃). Piezoelectric accelerometers manufactured using this material as the core have been practically applied in the aerospace and nuclear power fields.

[0100] The present invention has been described according to the above embodiments. It should be understood that the above embodiments do not limit the present invention in any way. All technical solutions obtained by equivalent substitution or equivalent transformation fall within the scope of the present invention.

Claims

1. A piezoelectric ceramic material, characterized in that, The piezoelectric ceramic material is represented by the following stoichiometric formula: Pb(Zr) 0.52 Ti 0.48 ) (1-x) Ta x O3-ywt%Ca (1-2z) M z Ce z Bi4Ti4O 15 Where M is at least one of Li, Na and K, 0.02≤x≤0.04, 0.4≤y≤1.2 and 0.015≤z≤0.

07.

2. The method for preparing the piezoelectric ceramic material according to claim 1, characterized in that, Includes the following steps: (1) PbO, ZrO2, Ta2O5 and TiO2 are added according to the stoichiometric formula Pb(ZrO2) in the above stoichiometric formula. 0.52 Ti 0.48 ) (1-x) Ta x O3 was prepared, and after ball milling, drying and grinding and pre-calcination, pre-calcined raw material A was obtained; (2) The carbonates of CaCO3, Bi2O3, CeO2, TiO2 and M are stoichiometrically prepared according to the stoichiometric formula in the above formula. (1-2z) M z Ce z Bi4Ti4O 15 The mixture is prepared, ball-milled, dried, ground, and pre-calcined to obtain pre-calcined raw material B; (3) Pre-calcined raw material A and pre-calcined raw material B are mixed according to the mass ratio of the stoichiometric formula and then ball-milled to obtain a mixed slurry; (4) Process the mixed slurry to make ceramic sheets; (5) Polish the surface of the ceramic sheet and print electrodes. After firing, the ceramic sheet is polarized by an electric field and aged to obtain the piezoelectric ceramic material.

3. The method for preparing piezoelectric ceramic materials as described in claim 2, characterized in that, In steps (1), (2), and (3), the ball milling method is planetary ball milling, and the rotation speed is 250–350 rad / min. In steps (1) and (2), the ball milling time is 3–5 h, and in step (3), the ball milling time is 5–7 h.

4. The method for preparing piezoelectric ceramic materials as described in claim 2, characterized in that, In steps (1) and (2), the preheating rate is 2-4℃ / min, the temperature is 800-900℃, and the time is 1.5-2.5h.

5. The method for preparing piezoelectric ceramic materials as described in claim 2, characterized in that, The process of processing the mixed slurry into ceramic sheets in step (4) includes the following steps: after drying the mixed slurry, a polyvinyl alcohol solution with a mass concentration of 6-12% is added for pelletizing, after drying, the mixture is sieved, and then pressed into ceramic green bodies under 6-10 MPa. After removing the binder from the ceramic green bodies, they are sintered to obtain ceramic sheets.

6. The method for preparing the piezoelectric ceramic material as described in claim 5, characterized in that, The debinding process includes the following steps: placing the ceramic green body in a debinding furnace and heating it to 550-650°C at a rate of 0.5-1.5°C / min, then allowing it to cool naturally to room temperature; the sintering process involves a heating rate of 2-4°C / min, a temperature of 1190-1250°C, and a time of 1.5-2.5 hours.

7. The method for preparing piezoelectric ceramic materials as described in claim 2, characterized in that, In step (5), the electrode is a silver electrode; the heating rate during firing is 8-12℃ / min, the temperature is 500-600℃, and the time is 8-12min.

8. The method for preparing piezoelectric ceramic materials as described in claim 2, characterized in that, The electric field polarization in step (5) includes the following steps: placing the fired ceramic sheet in silicone oil at 110-130°C, applying a DC electric field of 2.8-3.5kV to both ends of the sheet and holding the voltage for 5-10 minutes.

9. The method for preparing piezoelectric ceramic materials as described in claim 2, characterized in that, The aging temperature is 270–290℃, and the time is 45–50 hours.

10. The application of the piezoelectric ceramic material according to claim 1 in the preparation of a medium-temperature piezoelectric accelerometer.

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