Lead-free piezoelectric perovskite ceramic material and preparation method thereof

Abstract

The invention discloses a lead-free piezoelectric perovskite ceramic material and a preparation method thereof, and belongs to the technical field of piezoelectric ceramic dielectric materials. Bi (Zn2 / 3Nb1 / 3) O3 is introduced into (Ba0. 85Ca0. 15) (Zr0. 1Ti0. 9) O3 lead-free relaxor ferroelectric ceramic to prepare the lead-free piezoelectric perovskite ceramic material, the chemical composition general formula of the lead-free piezoelectric perovskite ceramic material is (1-x) (Ba0. 85Ca0. 15) (Zr0. 1Ti0. 9) O3-xBi (Zn2 / 3Nb1 / 3) O3, and the value range of x is 0.001-0.0125. According to the invention, Bi (Zn2 / 3Nb1 / 3) O3 is doped, so that the lead-free piezoelectric perovskite ceramic material generates a micro domain, and relatively high piezoelectric property and excellent light transmittance are obtained.

Description

Technical Field

[0001] The present invention belongs to the technical field of piezoelectric ceramic dielectric materials and relates to a lead-free piezoelectric perovskite ceramic material and a preparation method thereof. Background Art

[0002] Lead-free perovskite ceramic materials have become a key research direction in the field of piezoelectric ceramic dielectric materials due to their green nature. 0.85 Ca 0.15 )(Zr 0.1 Ti 0.9 )O3) possesses high piezoelectric properties and broad application prospects due to its numerous internal electric domains and easily reversible polarization orientation. However, BCZT ceramics have problems such as low Curie temperature, difficulty in polarization, and low transparency.

[0003] In the prior art, patent CN118851748A discloses a transparent piezoelectric ceramic material and its preparation method, the general formula of the piezoelectric ceramic material is (Na 1-x-y-z K z Li y Ca x )Nb 1-x Sn x O3, where x = 0.02-0.08, y = 0.02-0.10, z = 0.35-0.55. This patent improves the density of the ceramic by low-temperature vacuum pressurization. Although this patent improves the performance of BCZT ceramic materials, the piezoelectric coefficient of the improved piezoelectric ceramic material is not high, the transmittance in the visible light range is low, and the preparation conditions are limited, which further limits the performance improvement of the piezoelectric ceramic material. Summary of the Invention

[0004] In response to the problems and defects in the prior art, the present invention provides a lead-free piezoelectric perovskite ceramic material and a preparation method thereof, which solves the problems of low transparency and low piezoelectricity of BCZT ceramic materials and their modified materials in the prior art.

[0005] In the first aspect, the present invention provides a lead-free piezoelectric perovskite ceramic material, the chemical composition formula of the lead-free piezoelectric perovskite ceramic material is (1-x)(Ba 0.85 Ca 0.15 )(Zr 0.1 Ti 0.9 )O3-xBi(Zn 2 / 3 Nb 1 / 3 )O3;

[0006] The lead-free piezoelectric perovskite ceramic material is composed of (Ba 0.85 Ca 0.15 )(Zr 0.1Ti 0.9 )O3 and Bi(Zn 2 / 3 Nb 1 / 3 )O3 is prepared by solid solution in a molar ratio of (1-x):x; the value of x ranges from 0.001 to 0.0125.

[0007] Furthermore, in the lead-free piezoelectric perovskite ceramic material provided by the present invention, the piezoelectric coefficient of the lead-free piezoelectric perovskite ceramic material is 420-591 PC / N, and the electromechanical coupling coefficient is 0.31%-0.45%;

[0008] The transmittance of the lead-free piezoelectric perovskite ceramic material in the wavelength range of 300 to 800 nm is 72% to 84%.

[0009] In a second aspect, the present invention provides a method for preparing a lead-free piezoelectric perovskite ceramic material, comprising: weighing raw materials, mixing to obtain a mixture; ball milling, drying and pre-sintering the mixture in sequence to obtain a main crystalline phase powder; ball milling, drying, granulating, tableting, sintering and silver polarization of the main crystalline phase powder in sequence to obtain a lead-free piezoelectric perovskite ceramic material.

[0010] Furthermore, in the preparation method of a lead-free piezoelectric perovskite ceramic material provided by the present invention, the raw materials are prepared according to the chemical formula (1-x)(Ba 0.85 Ca 0.15 )(Zr 0.1 Ti 0.9 )O3-xBi(Zn 2 / 3 Nb 1 / 3 )O3's stoichiometric relationship: weigh ZrO2, CaCO3, TiO2, BaCO3, ZnO2, Bi2O3 and Nb2O3; the value range of x is 0.001~0.0125.

[0011] Furthermore, in the preparation method of a lead-free piezoelectric perovskite ceramic material provided by the present invention, anhydrous ethanol and zirconia balls need to be added when the mixture is ball-milled, and the mass ratio of the mixture, anhydrous ethanol and zirconia balls is 1:1.5:2;

[0012] The ball milling time of the mixture is 8 to 12 hours;

[0013] The drying time of the mixture is 2 to 4 hours, and the drying temperature is 80 to 100°C;

[0014] The pre-firing temperature of the mixture is 1000-1200° C., the pre-firing time is 3-5 hours, and the pre-firing heating rate is 3-5° C. / min.

[0015] Furthermore, in a method for preparing a lead-free piezoelectric perovskite ceramic material provided by the present invention, anhydrous ethanol and zirconia balls need to be added when the main crystalline phase powder is ball-milled, and the mass ratio of the main crystalline phase powder, anhydrous ethanol and zirconia balls is 1:1.5:2;

[0016] The ball milling time of the main crystal phase powder is 6 to 8 hours;

[0017] The drying time of the main crystal phase powder is 2 to 4 hours, and the drying temperature is 80 to 100°C;

[0018] When the main crystal phase powder is granulated, a binder needs to be added to obtain particles;

[0019] The pressure at which the main crystalline phase powder is pressed into tablets is 8 to 15 MPa.

[0020] Furthermore, in the preparation method of a lead-free piezoelectric perovskite ceramic material provided by the present invention, the binder is polyvinyl alcohol, and the mass concentration of the polyvinyl alcohol is 5% to 7%;

[0021] The size of the particles is 60-80 mesh.

[0022] Furthermore, in a preparation method of a lead-free piezoelectric perovskite ceramic material provided by the present invention, the main crystal phase powder is first heated to 600°C during sintering, debinding for 2 to 4 hours, then heated to 1450 to 1550°C, kept warm for 3 to 4 hours, cooled to 700°C, and cooled naturally.

[0023] Furthermore, in the method for preparing a lead-free piezoelectric perovskite ceramic material provided by the present invention, the heating rate is 3°C / min;

[0024] The cooling rate is 3-5°C / min.

[0025] Furthermore, in a preparation method of a lead-free piezoelectric perovskite ceramic material provided by the present invention, the silver polarization includes: after the main crystal phase powder is sintered, it is polished and cleaned, silver electrodes are coated on the front and back surfaces, and sintered at 600°C for 30 minutes.

[0026] Compared with the prior art, the technical solution provided by the present invention has at least the following beneficial effects or advantages:

[0027] (1) The present invention is to combine Bi(Zn 2 / 3 Nb 1 / 3 )O3 introduction (Ba 0.85 Ca 0.15 )(Zr 0.1 Ti 0.9)O3 lead-free relaxor ferroelectric ceramics, resulting in a lead-free piezoelectric perovskite ceramic material with a large number of microdomains, which increases the transmittance of the piezoelectric ceramic and significantly improves the piezoelectric performance. The preparation process of the present invention is simple, low-cost, suitable for mass production, and the raw materials do not contain lead, making it an environmentally friendly ceramic material that meets the needs of social development.

[0028] (2) The average grain size of the lead-free piezoelectric perovskite ceramic material provided by the present invention is 3.39 μm, and most of the grains are distributed between 2 and 4 μm. In addition, the lead-free piezoelectric perovskite ceramic material has a dense microstructure, clear grain boundaries and almost invisible voids, indicating that the preparation method of the lead-free piezoelectric perovskite ceramic material provided by the present invention has good sintering properties, which is beneficial to improving the transmittance of the ceramic.

[0029] (3) The lead-free piezoelectric perovskite ceramic material provided by the present invention has a light transmittance of 72% to 84% in the wavelength range of 300 to 800 nm, and under the irradiation of visible light, the letters behind the lead-free piezoelectric perovskite ceramic material can be clearly seen through the lead-free piezoelectric perovskite ceramic material, indicating that the lead-free piezoelectric perovskite ceramic material has a high transmittance in the near-ultraviolet band and the visible light band. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 This is a grain size diagram of the lead-free piezoelectric perovskite ceramic material prepared in Example 5.

[0031] Figure 2 This is the SEM image of the lead-free piezoelectric perovskite ceramic material prepared in Example 5.

[0032] Figure 3 This is a graph of the transmittance of lead-free piezoelectric perovskite ceramic materials in the wavelength range of 300 to 800 nm.

[0033] Figure 4 Transparency diagram of lead-free piezoelectric perovskite ceramic material under visible light. DETAILED DESCRIPTION

[0034] The technical solutions of the present invention are described below with reference to the following examples. However, the present invention is not limited to the following examples. The experimental methods and detection methods described in each example are conventional methods unless otherwise specified; the reagents and materials described are commercially available unless otherwise specified.

[0035] The highly transparent lead-free piezoelectric perovskite ceramic material involved in the following embodiments is made of (Ba 0.85 Ca 0.15 )(Zr 0.1 Ti 0.9 )O3 and Bi(Zn 2 / 3 Nb 1 / 3)O3 solid solution, (Ba 0.85 Ca 0.15 )(Zr 0.1 Ti 0.9 )O3 and Bi(Zn 2 / 3 Nb 1 / 3 )The molar ratio of O3 is (1-x):x, and the value of x is 0.001~0.0125.

[0036] Example 1

[0037] This embodiment provides a method for preparing a highly transparent lead-free piezoelectric perovskite ceramic material.

[0038] S1. According to the chemical formula (1-x)(Ba 0.85 Ca 0.15 )(Zr 0.1 Ti 0.9 )O3-xBi(Zn 2 / 3 Nb 1 / 3 )O3 calculate the molar ratio of Bi2O3, Na2CO3, TiO2, BaCO3, ZnO2, Bi2O3 and Nb2O3, where the value of x is 0.001. Bi2O3, Na2CO3, TiO2, BaCO3, ZnO2, Bi2O3 and Nb2O3 are mixed to obtain a mixture.

[0039] S2. Ball-mill the mixture for 8 hours, adding anhydrous ethanol and zirconia balls. The mass ratio of the mixture, anhydrous ethanol, and zirconia balls is 1:1.5:2. The milled mixture is transferred to an 80°C environment and dried for 4 hours. It is then pre-calcined at 1100°C for 4 hours at a heating rate of 5°C / min to obtain a primary crystalline phase powder.

[0040] S3. The main crystalline phase powder, anhydrous ethanol and zirconia balls are mixed and ball-milled for 6 hours. The mass ratio of the main crystalline phase powder, anhydrous ethanol and zirconia balls is 1:1.5:2. The ball-milled main crystalline phase powder is dried in an environment of 100°C for 2 hours. Then, a binder (polyvinyl alcohol) with a mass concentration of 7% is added to the dried main crystalline phase powder for granulation to obtain particles. The particles are screened through 60-mesh and 80-mesh sieves in turn, and the particles with a mesh size of 60-80 are screened for tableting. The pressure during tableting is 14 MPa to obtain ceramic green body.

[0041] S4. Sinter the ceramic green body. The sintering process includes: first, heating to 600°C at a rate of 3°C / min and keeping at that temperature for 3 hours to remove binder; then, heating to 1540°C at a rate of 3°C / min and keeping at that temperature for 4 hours; finally, cooling to 700°C at a rate of 5°C / min, and naturally cooling to obtain the ceramic material.

[0042] S5. After polishing and cleaning the lead-free perovskite ceramic material, silver electrodes are coated on both sides of the lead-free perovskite ceramic material, and the lead-free perovskite ceramic material is sintered at 600° C. for 30 minutes to obtain a lead-free piezoelectric perovskite ceramic material.

[0043] Example 2

[0044] This embodiment provides a method for preparing a highly transparent lead-free piezoelectric perovskite ceramic material.

[0045] S1. According to the chemical formula (1-x)(Ba 0.85 Ca 0.15 )(Zr 0.1 Ti 0.9 )O3-xBi(Zn 2 / 3 Nb 1 / 3 )O3 calculate the molar ratio of Bi2O3, Na2CO3, TiO2, BaCO3, ZnO2, Bi2O3 and Nb2O3, where the value of x is 0.002. Bi2O3, Na2CO3, TiO2, BaCO3, ZnO2, Bi2O3 and Nb2O3 are mixed to obtain a mixture.

[0046] S2. Ball-mill the mixture for 8 hours, adding anhydrous ethanol and zirconia balls. The mass ratio of the mixture, anhydrous ethanol, and zirconia balls is 1:1.5:2. The milled mixture is transferred to a 100°C environment and dried for 2 hours. It is then pre-calcined at 1000°C for 4 hours at a heating rate of 5°C / min to obtain a primary crystalline phase powder.

[0047] S3. The main crystalline phase powder, anhydrous ethanol and zirconia balls are mixed and ball-milled for 8 hours. The mass ratio of the main crystalline phase powder, anhydrous ethanol and zirconia balls is 1:1.5:2. The ball-milled main crystalline phase powder is dried in an environment of 80°C for 4 hours. Then, a binder (polyvinyl alcohol) with a mass concentration of 7% is added to the dried main crystalline phase powder for granulation to obtain particles. The particles are screened through 60-mesh and 80-mesh sieves in turn, and the particles with a mesh size of 60-80 are screened for tableting. The pressure during tableting is 14 MPa to obtain ceramic green body.

[0048] S4. Sinter the ceramic green body. The sintering process includes: first, heating to 600°C at a rate of 3°C / min and keeping at that temperature for 3 hours to remove binder; then, heating to 1550°C at a rate of 3°C / min and keeping at that temperature for 4 hours; finally, cooling to 700°C at a rate of 5°C / min, and naturally cooling to obtain the ceramic material.

[0049] S5. After polishing and cleaning the lead-free perovskite ceramic material, silver electrodes are coated on both sides of the lead-free perovskite ceramic material, and the lead-free perovskite ceramic material is sintered at 600° C. for 30 minutes to obtain a lead-free piezoelectric perovskite ceramic material.

[0050] Example 3

[0051] This embodiment provides a method for preparing a highly transparent lead-free piezoelectric perovskite ceramic material.

[0052] S1. According to the chemical formula (1-x)(Ba 0.85 Ca 0.15 )(Zr 0.1 Ti 0.9 )O3-xBi(Zn 2 / 3 Nb 1 / 3 )O3 calculate the molar ratio of Bi2O3, Na2CO3, TiO2, BaCO3, ZnO2, Bi2O3 and Nb2O3, where the value of x is 0.0025. Bi2O3, Na2CO3, TiO2, BaCO3, ZnO2, Bi2O3 and Nb2O3 are mixed to obtain a mixture.

[0053] S2. Ball-mill the mixture for 12 hours, adding anhydrous ethanol and zirconia balls. The mass ratio of the mixture, anhydrous ethanol, and zirconia balls is 1:1.5:2. The milled mixture is transferred to an 80°C environment and dried for 3 hours. It is then pre-calcined at 1100°C for 6 hours at a heating rate of 3°C / min to obtain a primary crystalline phase powder.

[0054] S3. The main crystalline phase powder, anhydrous ethanol and zirconia balls are mixed and ball-milled for 6 hours. The mass ratio of the main crystalline phase powder, anhydrous ethanol and zirconia balls is 1:1.5:2. The ball-milled main crystalline phase powder is dried in an environment of 80°C for 4 hours. Then, a binder (polyvinyl alcohol) with a mass concentration of 6% is added to the dried main crystalline phase powder for granulation to obtain particles. The particles are screened through 60-mesh and 80-mesh sieves in turn, and the particles with a mesh size of 60-80 are screened for tableting. The pressure during tableting is 12 MPa to obtain ceramic green body.

[0055] S4. Sinter the ceramic green body. The sintering process includes: first, heating to 600°C at a rate of 3°C / min and keeping at that temperature for 2 hours to remove binder; then, heating to 1520°C at a rate of 3°C / min and keeping at that temperature for 4 hours; finally, cooling to 700°C at a rate of 3°C / min and naturally cooling to obtain the ceramic material.

[0056] S5. After polishing and cleaning the lead-free perovskite ceramic material, silver electrodes are coated on both sides of the lead-free perovskite ceramic material, and the lead-free perovskite ceramic material is sintered at 600° C. for 30 minutes to obtain a lead-free piezoelectric perovskite ceramic material.

[0057] Example 4

[0058] This embodiment provides a method for preparing a highly transparent lead-free piezoelectric perovskite ceramic material.

[0059] S1. According to the chemical formula (1-x)(Ba 0.85 Ca 0.15 )(Zr 0.1 Ti 0.9 )O3-xBi(Zn 2 / 3 Nb 1 / 3 )O3 calculate the molar ratio of Bi2O3, Na2CO3, TiO2, BaCO3, ZnO2, Bi2O3 and Nb2O3, where the value of x is 0.005. Bi2O3, Na2CO3, TiO2, BaCO3, ZnO2, Bi2O3 and Nb2O3 are mixed to obtain a mixture.

[0060] S2. Ball-mill the mixture for 12 hours, adding anhydrous ethanol and zirconia balls. The mass ratio of the mixture, anhydrous ethanol, and zirconia balls is 1:1.5:2. The milled mixture is transferred to an 80°C environment and dried for 4 hours. It is then pre-calcined at 1100°C for 6 hours at a heating rate of 3°C / min to obtain a primary crystalline phase powder.

[0061] S3. The main crystalline phase powder, anhydrous ethanol and zirconia balls are mixed and ball-milled for 6 hours. The mass ratio of the main crystalline phase powder, anhydrous ethanol and zirconia balls is 1:1.5:2. The ball-milled main crystalline phase powder is dried in an environment of 80°C for 4 hours. Then, a binder (polyvinyl alcohol) with a mass concentration of 6% is added to the dried main crystalline phase powder for granulation to obtain particles. The particles are screened through 60-mesh and 80-mesh sieves in turn, and the particles with a mesh size of 60-80 are screened for tableting. The pressure during tableting is 10 MPa to obtain ceramic green body.

[0062] S4. Sinter the ceramic green body. The sintering process includes: first, heating to 600°C at a rate of 3°C / min and keeping at that temperature for 3 hours to remove binder; then, heating to 1520°C at a rate of 3°C / min and keeping at that temperature for 4 hours; finally, cooling to 700°C at a rate of 3°C / min, and naturally cooling to obtain the ceramic material.

[0063] S5. After polishing and cleaning the lead-free perovskite ceramic material, silver electrodes are coated on both sides of the lead-free perovskite ceramic material, and the lead-free perovskite ceramic material is sintered at 600° C. for 30 minutes to obtain a lead-free piezoelectric perovskite ceramic material.

[0064] Example 5

[0065] This embodiment provides a method for preparing a highly transparent lead-free piezoelectric perovskite ceramic material.

[0066] S1. According to the chemical formula (1-x)(Ba 0.85 Ca 0.15 )(Zr 0.1 Ti0.9 )O3-xBi(Zn 2 / 3 Nb 1 / 3 )O3 calculate the molar ratio of Bi2O3, Na2CO3, TiO2, BaCO3, ZnO2, Bi2O3 and Nb2O3, where the value of x is 0.0075. Bi2O3, Na2CO3, TiO2, BaCO3, ZnO2, Bi2O3 and Nb2O3 are mixed to obtain a mixture.

[0067] S2. Ball-mill the mixture for 12 hours, adding anhydrous ethanol and zirconia balls. The mass ratio of the mixture, anhydrous ethanol, and zirconia balls is 1:1.5:2. The milled mixture is transferred to an 80°C environment and dried for 4 hours. It is then pre-calcined at 1100°C for 6 hours at a heating rate of 3°C / min to obtain a primary crystalline phase powder.

[0068] S3. The main crystalline phase powder, anhydrous ethanol and zirconia balls are mixed and ball-milled for 6 hours. The mass ratio of the main crystalline phase powder, anhydrous ethanol and zirconia balls is 1:1.5:2. The ball-milled main crystalline phase powder is dried in an environment of 80°C for 4 hours. Then, a binder (polyvinyl alcohol) with a mass concentration of 6% is added to the dried main crystalline phase powder for granulation to obtain particles. The particles are screened through 60-mesh and 80-mesh sieves in turn, and the particles with a mesh size of 60-80 are screened for tableting. The pressure during tableting is 10 MPa to obtain ceramic green body.

[0069] S4. Sinter the ceramic green body. The sintering process includes: first, heating the temperature to 600°C at a rate of 3°C / min and keeping it at that temperature for 2 hours to remove the binder; then, heating the temperature to 1480°C at a rate of 3°C / min and keeping it at that temperature for 4 hours; finally, cooling the temperature to 700°C at a rate of 3°C / min and naturally cooling to obtain the ceramic material.

[0070] S5. After polishing and cleaning the lead-free perovskite ceramic material, silver electrodes are coated on both sides of the lead-free perovskite ceramic material, and the lead-free perovskite ceramic material is sintered at 600° C. for 30 minutes to obtain a lead-free piezoelectric perovskite ceramic material.

[0071] Example 6

[0072] This embodiment provides a method for preparing a highly transparent lead-free piezoelectric perovskite ceramic material.

[0073] S1. According to the chemical formula (1-x)(Ba 0.85 Ca 0.15 )(Zr 0.1 Ti 0.9 )O3-xBi(Zn 2 / 3 Nb 1 / 3)O3 calculate the molar ratio of Bi2O3, Na2CO3, TiO2, BaCO3, ZnO2, Bi2O3 and Nb2O3, where x is 0.01. Bi2O3, Na2CO3, TiO2, BaCO3, ZnO2, Bi2O3 and Nb2O3 are mixed to obtain a mixture.

[0074] S2. Ball-mill the mixture for 12 hours, adding anhydrous ethanol and zirconia balls. The mass ratio of the mixture, anhydrous ethanol, and zirconia balls is 1:1.5:2. The milled mixture is transferred to an 80°C environment and dried for 4 hours. It is then pre-calcined at 1100°C for 6 hours at a heating rate of 3°C / min to obtain a primary crystalline phase powder.

[0075] S3. The main crystalline phase powder, anhydrous ethanol and zirconia balls are mixed and ball-milled for 6 hours. The mass ratio of the main crystalline phase powder, anhydrous ethanol and zirconia balls is 1:1.5:2. The ball-milled main crystalline phase powder is dried in an environment of 80°C for 4 hours. Then, a binder (polyvinyl alcohol) with a mass concentration of 6% is added to the dried main crystalline phase powder for granulation to obtain particles. The particles are screened through 60-mesh and 80-mesh sieves in turn, and the particles with a mesh size of 60-80 are screened for tableting. The pressure during tableting is 8 MPa to obtain ceramic green body.

[0076] S4. Sintering the ceramic green body. The sintering process includes: first, heating to 600°C at a rate of 3°C / min and holding at that temperature for 2 hours to remove binder; then, heating to 1460°C at a rate of 3°C / min and holding at that temperature for 4 hours; finally, cooling to 700°C at a rate of 3°C / min and naturally cooling to obtain the ceramic material.

[0077] S5. After polishing and cleaning the lead-free perovskite ceramic material, silver electrodes are coated on both sides of the lead-free perovskite ceramic material, and the lead-free perovskite ceramic material is sintered at 600° C. for 30 minutes to obtain a lead-free piezoelectric perovskite ceramic material.

[0078] Example 7

[0079] This embodiment provides a method for preparing a highly transparent lead-free piezoelectric perovskite ceramic material.

[0080] S1. According to the chemical formula (1-x)(Ba 0.85 Ca 0.15 )(Zr 0.1 Ti 0.9 )O3-xBi(Zn 2 / 3 Nb 1 / 3)O3 calculate the molar ratio of Bi2O3, Na2CO3, TiO2, BaCO3, ZnO2, Bi2O3 and Nb2O3, where x is 0.0125. Bi2O3, Na2CO3, TiO2, BaCO3, ZnO2, Bi2O3 and Nb2O3 are mixed to obtain a mixture.

[0081] S2. Ball-mill the mixture for 8 hours, adding anhydrous ethanol and zirconia balls. The mass ratio of the mixture, anhydrous ethanol, and zirconia balls is 1:1.5:2. The milled mixture is transferred to an 80°C environment and dried for 2 hours. It is then pre-calcined at 1100°C for 6 hours at a heating rate of 5°C / min to obtain a primary crystalline phase powder.

[0082] S3. The main crystalline phase powder, anhydrous ethanol and zirconia balls are mixed and ball-milled for 6 hours. The mass ratio of the main crystalline phase powder, anhydrous ethanol and zirconia balls is 1:1.5:2. The ball-milled main crystalline phase powder is dried in an environment of 85°C for 4 hours. Then, a binder (polyvinyl alcohol) with a mass concentration of 5% is added to the dried main crystalline phase powder for granulation to obtain particles. The particles are screened through 60-mesh and 80-mesh sieves in turn, and the particles with a mesh size of 60-80 are screened for tableting. The pressure during tableting is 8 MPa to obtain ceramic green body.

[0083] S4. Sinter the ceramic green body. The sintering process includes: first, heating to 600°C at a rate of 3°C / min and keeping at that temperature for 2 hours to remove binder; then, heating to 1460°C at a rate of 3°C / min and keeping at that temperature for 4 hours; finally, cooling to 700°C at a rate of 5°C / min, and naturally cooling to obtain the ceramic material.

[0084] S5. After polishing and cleaning the lead-free perovskite ceramic material, silver electrodes are coated on both sides of the lead-free perovskite ceramic material, and the lead-free perovskite ceramic material is sintered at 600° C. for 30 minutes to obtain a lead-free piezoelectric perovskite ceramic material.

[0085] The present invention is to make Bi(Zn 2 / 3 Nb 1 / 3 )O3 introduction (Ba 0.85 Ca 0.15 )(Zr 0.1 Ti 0.9 )O3 lead-free relaxor ferroelectric ceramics, resulting in a lead-free piezoelectric perovskite ceramic material with a large number of microdomains, which increases the transmittance of the piezoelectric ceramic and significantly improves the piezoelectric performance. The preparation process of the present invention is simple, low-cost, suitable for mass production, and the raw materials do not contain lead, making it an environmentally friendly ceramic material that meets the needs of social development.

[0086] Table 1 shows the piezoelectric coefficient and electromechanical coupling coefficient of the lead-free piezoelectric perovskite ceramic material. As can be seen from the data in Table 1, the piezoelectric coefficient of the lead-free piezoelectric perovskite ceramic material provided by the present invention is 382-591 PC / N, while the electromechanical coupling coefficient is 0.28%-0.45%. Table 2 shows the transmittance of the lead-free piezoelectric perovskite ceramic material in different bands. As can be seen from Table 2, the transmittance of the lead-free piezoelectric perovskite ceramic material in the 366nm band is 76.35%-83.11%, and the transmittance in the 700nm band is 72.03%-79.44%, indicating that the transmittance of the lead-free piezoelectric perovskite ceramic material is high in the near-ultraviolet band, which decreases slightly in the visible light range, but still has a transmittance of more than 70%.

[0087] Table 1 Piezoelectric coefficients and electromechanical coupling coefficients of lead-free piezoelectric perovskite ceramic materials

[0088] sample <![CDATA[d 33 (PC / N)]]> kp(%) Example 1 420 0.35 Example 2 436 0.37 Example 3 450 0.39 Example 4 537 0.40 Example 5 591 0.45 Example 6 438 0.31 Example 7 382 0.28

[0089] Table 2 Transmittance of lead-free piezoelectric perovskite ceramic materials in different bands

[0090] sample T(366nm) T(700nm) Example 1 76.35％ 72.03％ Example 2 76.52％ 72.68％ Example 3 76.96％ 73.15％ Example 4 77.74％ 74.02％ Example 5 83.11％ 79.44％ Example 6 80.31％ 76.18％ Example 7 77.26％ 72.52％

[0091] Figure 1 The grain size diagram and scanning electron microscope image of the lead-free piezoelectric perovskite ceramic material provided in Example 5. The average grain size of the lead-free piezoelectric perovskite ceramic material in Example 5 is 3.39 μm, and most of the grains are distributed between 2 and 4 μm. The lead-free piezoelectric perovskite ceramic material has a dense microstructure, clear grain boundaries and almost invisible voids ( Figure 2 ), indicating that the preparation method of the lead-free piezoelectric perovskite ceramic material provided by the present invention has good sintering properties, which is beneficial to improving the transmittance of the ceramic.

[0092] Figure 3 is the light transmittance of the lead-free piezoelectric perovskite ceramic material of Examples 3 to 6 in the wavelength range of 300 to 800 nm, Figure 3 It can be seen that the light transmittance of the lead-free piezoelectric perovskite ceramic material provided by the present invention is 72% to 84% in the wavelength range of 00 to 800 nm. Figure 4 It can also be seen that the lead-free piezoelectric perovskite ceramic material provided by the present invention has a very high transmittance. Under the irradiation of visible light, the letters behind the lead-free piezoelectric perovskite ceramic material can be clearly seen through the lead-free piezoelectric perovskite ceramic material.

[0093] The embodiments described above are part of the embodiments of the present invention, rather than all of them. The detailed description of the embodiments of the present invention is not intended to limit the scope of the invention as claimed, but merely represents selected embodiments of the present invention. All other embodiments obtained without creative effort and through deduction and substitution by a person of ordinary skill in the art based on the concept of the present invention are within the scope of protection of the present invention.

Claims

1. A lead-free piezoelectric perovskite ceramic material, characterized in that: The chemical composition formula of the lead-free piezoelectric perovskite ceramic material is (1-x)(Ba 0.85 Ca 0.15 )(Zr 0.1 Ti 0.9 )O3-xBi(Zn 2 / 3 Nb 1 / 3 )O3; The lead-free piezoelectric perovskite ceramic material is composed of (Ba 0.85 Ca 0.15 )(Zr 0.1 Ti 0.9 )O3 and Bi(Zn 2 / 3 Nb 1 / 3 )O3 is prepared by solid solution in a molar ratio of (1-x):x; the value of x ranges from 0.001 to 0.0125.

2. The lead-free piezoelectric perovskite ceramic material according to claim 1, characterized in that: The lead-free piezoelectric perovskite ceramic material has a piezoelectric coefficient of 420 to 591 PC / N and an electromechanical coupling coefficient of 0.31% to 0.45%; The transmittance of the lead-free piezoelectric perovskite ceramic material in the wavelength range of 300 to 800 nm is 72% to 84%.

3. A method for preparing a lead-free piezoelectric perovskite ceramic material, characterized in that: include: Weighing raw materials and mixing them to obtain a mixture; ball milling, drying and pre-calcining the mixture in sequence to obtain a main crystal phase powder; The main crystal phase powder is sequentially subjected to ball milling, drying, granulation, tableting, sintering and silver polarization to obtain a lead-free piezoelectric perovskite ceramic material.

4. The method for preparing the lead-free piezoelectric perovskite ceramic material according to claim 3, wherein: The raw materials are according to the chemical formula (1-x)(Ba 0.85 Ca 0.15 )(Zr 0.1 Ti 0.9 )O3-xBi(Zn 2 / 3 Nb 1 / 3 )O3's stoichiometric relationship: weigh ZrO2, CaCO3, TiO2, BaCO3, ZnO2, Bi2O3 and Nb2O3; the value range of x is 0.001~0.0125.

5. The method for preparing the lead-free piezoelectric perovskite ceramic material according to claim 3, wherein: When the mixture is ball-milled, anhydrous ethanol and zirconium oxide balls need to be added, and the mass ratio of the mixture, anhydrous ethanol and zirconium oxide balls is 1:1.5:2; The ball milling time of the mixture is 8 to 12 hours; The drying time of the mixture is 2 to 4 hours, and the drying temperature is 80 to 100°C; The pre-firing temperature of the mixture is 1000-1200° C., the pre-firing time is 3-5 hours, and the pre-firing heating rate is 3-5° C. / min.

6. The method for preparing the lead-free piezoelectric perovskite ceramic material according to claim 3, wherein: When the main crystalline phase powder is ball-milled, anhydrous ethanol and zirconia balls need to be added, and the mass ratio of the main crystalline phase powder, anhydrous ethanol and zirconia balls is 1:1.5:2; The ball milling time of the main crystal phase powder is 6 to 8 hours; The drying time of the main crystal phase powder is 2 to 4 hours, and the drying temperature is 80 to 100°C; When the main crystal phase powder is granulated, a binder needs to be added to obtain particles; The pressure at which the main crystalline phase powder is pressed into tablets is 8 to 15 MPa.

7. The method for preparing the lead-free piezoelectric perovskite ceramic material according to claim 6, characterized in that: The binder is polyvinyl alcohol, and the mass concentration of polyvinyl alcohol is 5% to 7%; The size of the particles is 60-80 mesh.

8. The method for preparing the lead-free piezoelectric perovskite ceramic material according to claim 3, wherein: When the main crystal phase powder is sintered, the temperature is first raised to 600° C., the binder is removed for 2 to 4 hours, the temperature is then raised to 1450 to 1550° C., the temperature is kept for 3 to 4 hours, the temperature is then lowered to 700° C., and the powder is cooled naturally.

9. The method for preparing the lead-free piezoelectric perovskite ceramic material according to claim 8, characterized in that: The heating rate is 3°C / min; The cooling rate is 3-5°C / min.

10. The method for preparing a lead-free piezoelectric perovskite ceramic material according to claim 3, wherein: The silver polarization includes: sintering the main crystal phase powder, polishing and cleaning it, coating silver electrodes on the front and back surfaces, and sintering it at 600° C. for 30 minutes.

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