Preparation method of low-lead piezoelectric ceramic material and ceramic

Abstract

The invention relates to a low-lead piezoelectric ceramic material preparation method and ceramic, and the method comprises the following steps: weighing raw materials according to the atomic percentage of the chemical formula (Ba1-xAx) (ByTi1-y) O3, mixing the raw materials, carrying out first ball milling, and drying the ball-milled raw materials to obtain raw material powder; compacting the raw material powder, pre-sintering to obtain a block body, crushing the block body, adding deionized water, carrying out secondary ball milling, and drying to obtain synthetic powder; mixing an organic solvent and the synthetic powder, and carrying out third ball milling to obtain slurry; uniformly pouring the slurry on a film belt of a casting machine, and scraping the slurry through a scraper; airing to obtain a raw ceramic tape of the barium titanate-based thick film ceramic with the high breakdown field; and cutting the raw ceramic tape into raw ceramic chips, and sintering the raw ceramic chips in a muffle furnace to obtain the high-breakdown-field barium titanate-based thick-film ceramic with the high breakdown field of 100-140 kV / cm.

Description

Technical Field

[0001] The present invention relates to the technical field of piezoelectric ceramic materials, and in particular to a preparation method of a low-lead piezoelectric ceramic material and ceramics. Background Art

[0002] Ferroelectric materials, due to their unique multifunctional properties, including dielectric, piezoelectric, pyroelectric, ferroelectric, and optoelectronic / acousto-optic effects, hold significant application value in defense, military, biomedicine, aerospace, and precision manufacturing. As modern electronic devices evolve toward miniaturization and greener manufacturing, traditional lead-based ferroelectric material systems face significant technical challenges. While lead-based materials, such as lead zirconate titanate (PZT), exhibit excellent piezoelectric response (d33 > 500 pC / N) and high Curie temperature (Tc ≈ 350°C), the biotoxicity and environmental risks associated with lead volatilization during their preparation severely hinder their sustainable development. Existing lead-free alternative materials (such as barium titanate- and potassium sodium niobate-based ceramics) generally suffer from technical bottlenecks such as low piezoelectric coefficient, low Curie temperature, poor temperature stability, and high dielectric loss.

[0003] The above information disclosed in this Background section is only for enhancement of understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known to a person of ordinary skill in the art. Summary of the Invention

[0004] This invention provides a method for preparing low-lead piezoelectric ceramic materials and ceramics, addressing the problems of current lead-free ceramics, such as poor piezoelectric performance, low Curie temperature, poor temperature stability, high hysteresis, and high leakage current. This method overcomes the technical barriers to synergistically optimizing high piezoelectric performance and environmental friendliness in existing material systems, achieving the dual optimization goals of piezoelectric performance and lead content through component design and microstructural control.

[0005] A method for preparing a low-lead piezoelectric ceramic material comprises: Step S100, according to the chemical formula (1-x)Ba(Sn 0.2 Ti 0.8 )O3- x(Ba 0.8 Pb 0.2 ) Calculation of the atomic percentage of TiO3, weighing BaCO3, TiO2, SnO2, and PbO raw materials, and then first ball milling them, mixing them, and drying them to obtain a raw material powder, wherein x is 0.0 to 1.0, and the atomic percentage of Pb is ≤4%; Step S200, compacting the raw material powder and then calcining it, and then performing a second ball milling to obtain a synthetic powder; Step S300, adding a binder to the synthetic powder, granulating, and tableting to obtain a green body; Step S400: heat-treating the green body to obtain a low-lead piezoelectric ceramic material.

[0006] In the method for preparing a low-lead piezoelectric ceramic material, in step S100, the first ball milling includes wet ball milling, deionized water and agate balls are used as the medium, and the raw materials and deionized water are mixed in a mass percentage ratio of 1:1 and ball milled for 3.5-4.5 hours.

[0007] In the method for preparing a low-lead piezoelectric ceramic material, in step S200, the calcination temperature is 1180-1220°C, the calcination time is 1.5-2.5h, the calcination heating rate is 3-4°C / min, and the calcined product is cooled to room temperature in the furnace.

[0008] In the method for preparing a low-lead piezoelectric ceramic material, the second ball milling includes wet ball milling, and after the second wet ball milling is performed for 4.5-5.5 hours, the powder is dried to obtain a synthetic powder.

[0009] In the method for preparing a low-lead piezoelectric ceramic material, in step S300, the binder is polyvinyl alcohol.

[0010] In the method for preparing a low-lead piezoelectric ceramic material, in step S300, the particle size of the tabletting material is such that it passes through a 60-mesh sieve but does not pass through a 100-mesh sieve, and the pressure during tabletting is set to 14-18 MPa.

[0011] In the method for preparing a low-lead piezoelectric ceramic material, step S400 includes the following steps: S401, set the heating rate to 1-2°C / mins to 450-550°C, and keep warm for 0.8-1.2h; S402, setting the heating rate to 1.5-2.5°C / mins to raise the temperature to 1200-1300°C, keeping the temperature for 2.5-3.5 hours, and then cooling to room temperature with the furnace to obtain a low-lead piezoelectric ceramic material.

[0012] In the method for preparing a low-lead piezoelectric ceramic material, Ba(Sn 0.2 Ti 0.8 )O3 and (Ba 0.8 Pb 0.2 )TiO3 as the endpoint component to construct the morphotropic phase boundary, the left endpoint Ba(Sn 0.2 Ti 0.8 )O3 changes from cubic phase to rhombohedral phase at 17° as the temperature decreases. The right endpoint (Ba 0.8 Pb 0.2 )TiO3 transforms from cubic phase to tetragonal phase at 220° as the temperature decreases, and the left and right endpoint components form a stable solid solution.

[0013] A low-lead piezoelectric ceramic is prepared by the method.

[0014] In the low-lead piezoelectric ceramic, when the thickness of the low-lead piezoelectric ceramic is less than 1 mm and the diameter is less than 1 mm, the piezoelectric constant d 33 Reach 50~270pC / N.

[0015] Compared with the prior art, the present invention has the following advantages: the ferroelectric ceramic material has a higher piezoelectric constant (d 33 ), and when the thickness of the ceramic system is less than 1mm and the diameter is less than 1mm, d33 can still reach a maximum of 270pC / N to meet the requirements of small size and low pollution of piezoelectric devices; Ba(Sn 0.2 Ti 0.8 )O3 and (Ba 0.8 Pb 0.2 )TiO3 as the endpoint component to construct the morphotropic phase boundary, the left endpoint Ba(Sn 0.2 Ti 0.8 )O3 changes from cubic phase to rhombohedral phase around 17° as the temperature decreases. The right endpoint (Ba 0.8 Pb 0.2 As the temperature decreases, TiO3 transforms from a cubic phase to a tetragonal phase around 220°C, and the left and right endpoint components can form a stable solid solution. Ferroelectric ceramic materials, when doped with a small amount of lead, exhibit a high piezoelectric constant, meeting the requirements of small-size and low-pollution piezoelectric devices.

[0016] The heat treatment method of the present invention can promote the uniform growth of ferroelectric ceramic grains, improve density, and avoid abnormal grain coarsening or loose structure; reasonable control of the heating rate can effectively eliminate organic residues and reduce thermal stress cracks, while optimizing the grain boundary diffusion and densification process, and ultimately significantly improve the piezoelectric constant (in an optimal embodiment of the present invention, d33 reaches 270pC / N), providing a reliable foundation for applications such as high-performance sensors and transducers. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Various other advantages and benefits of the present invention will become apparent to those skilled in the art upon reading the detailed description of the preferred embodiments below. The accompanying drawings are intended only to illustrate preferred embodiments and are not to be construed as limiting the present invention. It should be understood that the drawings described below are merely examples of the present invention, and that those skilled in the art will be able to derive other drawings from these drawings without inventive effort. Throughout the drawings, identical reference numerals are used to denote identical components.

[0018] In the attached figure: Figure 1 A low-lead ferroelectric ceramic material (1-x)Ba(Sn 0.2 Ti0.8 )O3- x(Ba 0.8 Pb 0.2 ) X-ray diffraction pattern of TiO3 near 45°; Figure 2 A low-lead ferroelectric ceramic material (1-x)Ba(Sn 0.2 Ti 0.8 )O3- x(Ba 0.8 Pb 0.2 )TiO3, Curie temperature Tc, piezoelectric coefficient d33, peak dielectric constant ε max Schematic diagram.

[0019] The present invention will be further explained below with reference to the accompanying drawings and embodiments. DETAILED DESCRIPTION

[0020] Specific embodiments of the present invention will be described in more detail below with reference to the accompanying drawings. Although specific embodiments of the present invention are shown in the accompanying drawings, it should be understood that the present invention can be implemented in various forms and should not be limited by the embodiments set forth herein. Rather, these embodiments are provided to enable a more thorough understanding of the present invention and to fully convey the scope of the present invention to those skilled in the art.

[0021] It should be noted that certain words are used in the specification and claims to refer to specific components. Those skilled in the art should understand that technicians may use different nouns to refer to the same component. This specification and claims do not use the difference in nouns as a way to distinguish components, but use the difference in the functions of the components as the criterion for distinction. As mentioned throughout the specification and claims, "including" or "comprising" is an open term, so it should be interpreted as "including but not limited to". The subsequent description of the specification is a preferred embodiment of the present invention, but the description is based on the general principles of the specification and is not intended to limit the scope of the invention. The scope of protection of the present invention shall be as defined in the attached claims.

[0022] To facilitate understanding of the embodiments of the present invention, further explanation will be given below using specific embodiments as examples in conjunction with the accompanying drawings, and the accompanying drawings do not constitute a limitation on the embodiments of the present invention.

[0023] like Figures 1 to 2 As shown, the method for preparing low-lead piezoelectric ceramic material includes the following steps: Step S100, according to the chemical formula (1-x)Ba(Sn 0.2 Ti 0.8 )O3- x(Ba 0.8 Pb 0.2) Calculation of the atomic percentage of TiO3, weighing BaCO3, TiO2, SnO2, and PbO raw materials, and then first ball milling them, mixing them, and drying them to obtain a raw material powder, wherein x is 0.0 to 1.0, and the atomic percentage of Pb is ≤4%; Step S200, compacting the raw material powder and then calcining it, and then performing a second ball milling to obtain a synthetic powder; Step S300, adding a binder to the synthetic powder, granulating, and tableting to obtain a green body; Step S400: heat-treating the green body to obtain a low-lead piezoelectric ceramic material.

[0024] In a preferred embodiment of the method for preparing a low-lead piezoelectric ceramic material, in step S100, the first ball milling includes wet ball milling, deionized water and agate balls are used as media, and the raw materials and deionized water are mixed in a mass percentage ratio of 1:1 and ball milled for 3.5-4.5 hours.

[0025] In a preferred embodiment of the method for preparing a low-lead piezoelectric ceramic material, in step S200, the calcination temperature is 1180-1220°C, the calcination time is 1.5-2.5h, the calcination heating rate is 3-4°C / min, and the calcined product is cooled to room temperature with the furnace.

[0026] In a preferred embodiment of the method for preparing a low-lead piezoelectric ceramic material, the second ball milling includes wet ball milling, and after the second wet ball milling for 4.5-5.5 hours, the synthetic powder is dried.

[0027] In a preferred embodiment of the method for preparing a low-lead piezoelectric ceramic material, in step S300, the binder is polyvinyl alcohol.

[0028] In a preferred embodiment of the method for preparing a low-lead piezoelectric ceramic material, in step S300, the particle size of the tabletting material is such that it passes through a 60-mesh sieve but does not pass through a 100-mesh sieve, and the pressure during tabletting is set to 14-18 MPa.

[0029] In a preferred embodiment of the method for preparing a low-lead piezoelectric ceramic material, step S400 includes the following steps: S401, set the heating rate to 1-2°C / mins to 450-550°C, and keep warm for 0.8-1.2h; S402, setting the heating rate to 1.5-2.5°C / mins to raise the temperature to 1200-1300°C, keeping the temperature for 2.5-3.5 hours, and then cooling to room temperature with the furnace to obtain a low-lead piezoelectric ceramic material.

[0030] In a preferred embodiment of the method for preparing a low-lead piezoelectric ceramic material, Ba(Sn 0.2 Ti 0.8)O3 and (Ba 0.8 Pb 0.2 )TiO3 as the endpoint component to construct the morphotropic phase boundary, the left endpoint Ba(Sn 0.2 Ti 0.8 )O3 changes from cubic phase to rhombohedral phase at 17° as the temperature decreases. The right endpoint (Ba 0.8 Pb 0.2 )TiO3 transforms from cubic phase to tetragonal phase at 220° as the temperature decreases, and the left and right endpoint components form a stable solid solution.

[0031] A low-lead piezoelectric ceramic is prepared by the method.

[0032] In a preferred embodiment of a low-lead piezoelectric ceramic, when the thickness of the low-lead piezoelectric ceramic is less than 1 mm and the diameter is less than 1 mm, the piezoelectric constant d 33 The highest reaches 270pC / N.

[0033] In one embodiment, a low-lead piezoelectric ceramic material is provided, wherein the chemical formula of the material is (1-x)Ba(Sn 0.2 Ti 0.8 )O3- x(Ba 0.8 Pb 0.2 )TiO3, wherein x=0.0~1.0, and the atomic percentage of Pb is ≤4%.

[0034] The method comprises the following steps: S100, according to the chemical formula of the material (1-x)Ba(Sn 0.2 Ti 0.8 )O3- x(Ba 0.8 Pb 0.2 ) Calculate the atomic percentage of TiO3, weigh BaCO3, TiO2, SnO2, and PbO raw materials, fully mix them, and dry them to obtain raw material powders; S200, compacting the raw material powder and then calcining it, and then wet-milling the product twice to obtain a synthetic powder; S300, adding a binder to the synthetic powder, granulating the powder, and tableting to obtain a green body; S400, heat-treating the green body to obtain a low-lead ferroelectric ceramic material.

[0035] In a preferred embodiment, the step S100 of fully mixing is to fully mix the raw materials by wet ball milling, using deionized water and agate balls as the medium, and mixing and ball milling for 6 hours in a ratio of raw materials to deionized water of 1:1 by mass.

[0036] In a preferred embodiment, in step S200, the calcination temperature is 1180-1220°C, the calcination time is 1.5-2.5h, the calcination heating rate is 3-4°C / min, the calcined product is cooled to room temperature with the furnace, and then crushed, wet-milled for a second time for 8h, and then dried to obtain a synthetic powder.

[0037] In a preferred embodiment, the adhesive in step S300 is polyvinyl alcohol, the particle size of the tabletting material is such that it can pass through a 60-mesh sieve but cannot pass through a 100-mesh sieve, and the pressure during tableting is set to 14-18 MPa.

[0038] In a preferred embodiment, the heat treatment in step S400 further comprises the following steps: S401, set the heating rate to 2°C / mins and raise the temperature to 500°C, and keep it at this temperature for 1 hour; S402, setting the heating rate to 1.5-2.5°C / mins to raise the temperature to 1200-1300°C, keeping the temperature for 2.5-3.5 hours, and then cooling to room temperature with the furnace to obtain a low-lead ferroelectric ceramic material.

[0039] Example 1 BaCO3 with a purity of 0.998, TiO2 with a purity of 0.995, SnO2 with a purity of 0.99, and PbO with a purity of 0.999 are prepared according to the chemical composition of the lead-free piezoelectric ceramic material. 0.3Ba(Sn 0.2 Ti 0.8 )O3- 0.7(Ba 0.8 Pb 0.2 ) TiO3 was mixed and wet-milled to obtain a raw material powder. Deionized water and agate balls were used as the medium for the wet milling. The raw material and deionized water were mixed in a ratio of 1:1 and the wet milling was carried out for 6 hours.

[0040] The raw material powder was compacted in an alumina crucible, covered with a lid, and calcined at 1200°C for 2 hours at a heating rate of 3.5°C / min. The material was cooled to room temperature and then pulverized. After a second wet ball milling process for 8 hours, the material was dried to obtain a synthetic powder.

[0041] The synthetic powder and a binder are mixed and granulated, wherein the binder can be polyvinyl alcohol (PVA). The granulated powder is passed through a 60-mesh sieve and a 100-mesh sieve respectively, and the portion that passes through the 60-mesh sieve but not the 100-mesh sieve is taken for tableting.

[0042] The sieved powder was pressed into discs with a diameter of about 1 cm and a thickness of about 1 mm at 16 MPa to obtain a green body.

[0043] The green body was heated in a muffle furnace for plastic removal and constant temperature sintering. The temperature was raised from room temperature to 500°C at a rate of 2°C / min, held at that temperature for 1 hour, and then sintered to 1250°C at a rate of 2°C / min, held at that temperature for 3 hours, and then cooled to room temperature in the furnace to obtain a low-lead ferroelectric ceramic material with a large piezoelectric effect.

[0044] The two parallel surfaces of the sintered large piezoelectric effect low-lead ferroelectric ceramic material are coated with silver by screen printing, and the silver is sintered at 800°C for 30 minutes to obtain a silver electrode.

[0045] The composition is 0.3Ba(Sn 0.2 Ti 0.8 )O3- 0.7(Ba 0.8 Pb 0.2 )TiO3 low-lead large piezoelectric material, the material characterization experiment measured the Curie temperature Tc = 77 ° C, d 33 =270pC / N.

[0046] Example 2 Preparation composition is 0.4Ba(Sn 0.2 Ti 0.8 )O3- 0.6(Ba 0.8 Pb 0.2 )TiO3, that is, x = 0.6 low-lead large piezoelectric material, the difference is that the purity of 0.998 BaCO3, the purity of 0.995 TiO2, the purity of 0.99 SnO2, the purity of 0.999 PbO according to the chemical composition of lead-free piezoelectric ceramic materials 0.4Ba (Sn 0.2 Ti 0.8 )O3- 0.6(Ba 0.8 Pb 0.2 )TiO3 is used for batching.

[0047] The raw materials were mixed and dried by wet ball milling to obtain raw material powder. Deionized water and agate balls were used as the medium for wet ball milling. The raw materials were mixed in a ratio of 1:1 with deionized water, and the wet ball milling was carried out for 6 hours.

[0048] The raw material powder was compacted in an alumina crucible, covered with a lid, and calcined at 1220°C for 1.5 hours at a heating rate of 4°C / min. The product was then cooled to room temperature and pulverized. After a second wet ball milling process for 8 hours, the product was dried to obtain a synthetic powder.

[0049] The synthetic powder and a binder are mixed and granulated, wherein the binder can be polyvinyl alcohol (PVA). The granulated powder is passed through a 60-mesh sieve and a 100-mesh sieve respectively, and the portion that passes through the 60-mesh sieve but not the 100-mesh sieve is taken for tableting.

[0050] The sieved powder was pressed into discs with a diameter of about 1 cm and a thickness of about 1 mm at 14 MPa to obtain a green body.

[0051] The green body was heated in a muffle furnace for plastic removal and constant temperature sintering. The temperature was raised from room temperature to 500°C at a rate of 2°C / min, held for 1 hour, and then sintered at a rate of 2.5°C / min to 1300°C, held for 2.5 hours, and then cooled to room temperature. This yielded a low-lead ferroelectric ceramic material with a large piezoelectric effect.

[0052] The two parallel surfaces of the sintered large piezoelectric effect low-lead ferroelectric ceramic material are coated with silver by screen printing, and the silver is sintered at 800°C for 30 minutes to obtain a silver electrode.

[0053] The Curie temperature of the material was measured to be Tc = 95.5 ° C. 33 =245pC / N.

[0054] Example 3 Preparation composition is 0.2Ba(Sn 0.2 Ti 0.8 )O3-0.8(Ba 0.8 Pb 0.2 )TiO3, that is, x = 0.4 low-lead large piezoelectric material, the difference is that the purity of 0.998 BaCO3, the purity of 0.995 TiO2, the purity of 0.99 SnO2, the purity of 0.999 PbO according to the chemical composition of lead-free piezoelectric ceramic materials 0.6Ba (Sn 0.2 Ti 0.8 )O3-0.4(Ba 0.8 Pb 0.2 )TiO3 is used for batching.

[0055] The raw materials were mixed and dried by wet ball milling to obtain raw material powder. Deionized water and agate balls were used as the medium for wet ball milling. The raw materials were mixed in a ratio of 1:1 with deionized water, and the wet ball milling was carried out for 6 hours.

[0056] The raw material powder was compacted in an alumina crucible, covered, and calcined at 1180°C for 2.5 hours at a heating rate of 3°C / min. The material was then cooled to room temperature and pulverized. After a second wet ball milling, the material was dried to obtain a synthetic powder.

[0057] The synthetic powder and a binder are mixed and granulated, wherein the binder can be polyvinyl alcohol (PVA). The granulated powder is passed through a 60-mesh sieve and a 100-mesh sieve respectively, and the portion that passes through the 60-mesh sieve but not the 100-mesh sieve is taken for tableting.

[0058] The sieved powder was pressed into discs with a diameter of about 1 cm and a thickness of about 1 mm at 18 MPa to obtain a green body.

[0059] The green body was heated in a muffle furnace for plastic removal and constant temperature sintering. The temperature was raised from room temperature to 500°C at a heating rate of 2°C / min, held at that temperature for 1 hour, and then sintered to 1200°C at a heating rate of 1.5°C / min, held at that temperature for 3.5 hours, and then cooled to room temperature in the furnace to obtain a low-lead ferroelectric ceramic material with a large piezoelectric effect.

[0060] The two parallel surfaces of the sintered large piezoelectric effect low-lead ferroelectric ceramic material are coated with silver by screen printing, and the silver is sintered at 800°C for 30 minutes to obtain a silver electrode.

[0061] The Curie temperature Tc of the material was measured to be 53.5°C through material characterization experiments. 33 It is 30pC / N.

[0062] like Figure 1 A low-lead ferroelectric ceramic material (1-x)Ba(Sn 0.2 Ti 0.8 )O3- x(Ba 0.8 Pb 0.2 ) X-ray diffraction pattern of TiO3 near 45°, from the Sn-rich end to the Pb-rich end, the (200) peak gradually splits from a single peak into two diffraction peaks as x increases. The BST-xBPT system undergoes a phase transition from rhombohedral phase to tetragonal phase as the composition changes.

[0063] like Figure 2 A low-lead ferroelectric ceramic material (1-x)Ba(Sn 0.2 Ti 0.8 )O3- x(Ba 0.8 Pb 0.2 )TiO3, Curie temperature Tc, piezoelectric coefficient d33, peak dielectric constant ε max At room temperature, the components near the quasi-isotropic phase boundary all show relatively large piezoelectricity. With the increase of lead doping amount, the Curie temperature and coercive force both increase, and polarization reversal becomes increasingly difficult under DC bias.

[0064] Although the embodiments of the present invention have been described above with reference to the accompanying drawings, the present invention is not limited to the above-mentioned specific embodiments and application fields. The above-mentioned specific embodiments are merely illustrative and instructive, and are not restrictive. A person skilled in the art, guided by this specification and without departing from the scope of protection of the claims of the present invention, may also devise various forms, all of which fall within the scope of protection of the present invention.

Claims

1. A method for preparing a low-lead piezoelectric ceramic material, characterized in that: The steps include: Step S100, according to the chemical formula (1-x)Ba(Sn 0.2 Ti 0.8 )O3- x(Ba 0.8 Pb 0.2 ) Calculation of the atomic percentage of TiO3, weighing BaCO3, TiO2, SnO2, and PbO raw materials, and then first ball milling them, mixing them, and drying them to obtain a raw material powder, wherein x is 0.0 to 1.0, and the atomic percentage of Pb is ≤4%; Step S200, compacting the raw material powder and then calcining it, and then performing a second ball milling to obtain a synthetic powder; Step S300, adding a binder to the synthetic powder, granulating, and tableting to obtain a green body; Step S400: heat-treating the green body to obtain a low-lead piezoelectric ceramic material.

2. The method for preparing a low-lead piezoelectric ceramic material according to claim 1, characterized in that: Preferably, in step S100, the first ball milling includes wet ball milling, deionized water and agate balls are used as media, and the raw materials and deionized water are mixed in a ratio of 1:1 by mass and ball milled for 3.5-4.5 hours.

3. The method for preparing a low-lead piezoelectric ceramic material according to claim 1, characterized in that: In step S200, the calcination temperature is 1180-1220°C, the calcination time is 1.5-2.5 hours, the calcination heating rate is 3-4°C / min, and the calcined product is cooled to room temperature in the furnace.

4. The method for preparing a low-lead piezoelectric ceramic material according to claim 1, characterized in that: The second ball milling includes wet ball milling. After the second wet ball milling for 4.5-5.5 hours, the synthetic powder is dried.

5. The method for preparing a low-lead piezoelectric ceramic material according to claim 1, characterized in that: In step S300, the adhesive is polyvinyl alcohol.

6. The method for preparing a low-lead piezoelectric ceramic material according to claim 1, characterized in that: In step S300 , the particle size of the tabletting material is such that it passes through a 60-mesh sieve but does not pass through a 100-mesh sieve, and the pressure during tableting is set to 14-18 MPa.

7. The method for preparing a low-lead piezoelectric ceramic material according to claim 1, characterized in that: Step S400 includes the following steps: S401, set the heating rate to 1-2°C / mins to 450-550°C, and keep warm for 0.8-1.2h; S402, setting the heating rate to 1.5-2.5°C / mins to raise the temperature to 1200-1300°C, keeping the temperature for 2.5-3.5 hours, and then cooling the furnace to room temperature to obtain a low-lead piezoelectric ceramic material.

8. The method for preparing a low-lead piezoelectric ceramic material according to claim 1, characterized in that: Ba(Sn 0.2 Ti 0.8 )O3, that is, x=0.0 and (Ba 0.8 Pb 0.2 )TiO3, x = 1.0 as the endpoint composition to construct the morphotropic phase boundary, the left endpoint Ba(Sn 0.2 Ti 0.8 )O3 changes from cubic phase to rhombohedral phase at 17° as the temperature decreases. The right endpoint (Ba 0.8 Pb 0.2 )TiO3 transforms from cubic phase to tetragonal phase at 220° as the temperature decreases, and the left and right endpoint components form a stable solid solution.

9. A low-lead piezoelectric ceramic, characterized in that: It is prepared by the method according to any one of claims 1 to 8.

10. The low-lead piezoelectric ceramic according to claim 9, characterized in that: When the thickness of low-lead piezoelectric ceramics is less than 1mm and the diameter is less than 1mm, the piezoelectric constant d 33 Reach 50~270pC / N.

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