Bismuth-ferrite-based lead-free piezoelectric ceramic material and preparation method therefor

Abstract

A bismuth-ferrite-based lead-free piezoelectric ceramic material and a preparation method therefor. The preparation method comprises: step 1, grinding and mixing raw materials at a molar ratio of Fe2O3 to Bi2O3 to TiO2 to BaCO3 to CuO to xLi2CO3 of 0.375:0.375:0.25:0.25:0.006:x, so as to obtain an original mixed material, wherein 0≤x≤0.9%; and preparing a pre-pressed sheet from the original mixed material, sintering same to obtain a pre-sintered sample, subjecting the pre-sintered sample to grinding, granulating and tabletting shaping, and sintering the resulting tabletting shaped sample, so as to obtain a bismuth-ferrite-based lead-free piezoelectric ceramic material. To address the problem of a BiFeO3-BaTiO3-based ceramic material having relatively poor crystallization properties, a relatively high sintering temperature and poor electrical properties, it is proposed to subject 0.75BiFeO3-0.25BaTiO3 to CuO-Li2CO3 co-doping modification, such that the crystallization properties thereof are significantly improved, the ceramic quality is improved, and the prepared piezoelectric ceramic material has good multifunctionality, shows a saturated ferroelectric hysteresis loop, and has significant dielectric and piezoelectric responsiveness.

Description

A bismuth ferrite-based lead-free piezoelectric ceramic material and its preparation method Technical Field

[0001] The invention belongs to the technical field of ferroic functional ceramic materials and relates to a bismuth ferrite-based lead-free piezoelectric ceramic material and a preparation method thereof. Background Art

[0002] Bismuth ferrite (BFO) initially attracted widespread attention from researchers of multiferroic materials due to its ability to exhibit both ferroelectricity and antiferromagnetism at room temperature. In addition to possessing both ferroelectricity and magnetic order, multiferroic materials also possess a crucial feature: the coupling between the ferroelectric and magnetic order, offering enormous potential for the development of magnetoelectric and information storage devices. Compared to the widely used lead zirconate titanate (PZT) and lead magnesium niobate-titanate (PMN-PT)-based piezoelectric materials, bismuth ferrite (BFO) is a perovskite ferroelectric material with an ultrahigh spontaneous polarization. This material holds broad application prospects in ferroelectric memories, piezoelectric actuators, sensors, and transducers. Furthermore, its high ferroelectric phase transition temperature (~850°C) suggests that it holds great potential as a high-temperature piezoelectric material, attracting increasing attention.

[0003] However, the performance of BFO bulk ceramics is often very poor. This is related to the instability of the phase structure, the presence of impurities and defects in BFO ceramics, resulting in large leakage conductance and poor dielectric strength. This is a serious problem for BFO with a high coercive field, making it extremely difficult to polarize and unable to obtain good ferroelectric properties. BFO can form a complete solid solution with other perovskite systems such as barium titanate or lead titanate, and in certain component regions it will show the presence of a quasi-modular phase boundary (MPB) and an enhanced piezoelectric effect. However, compared with traditional commercial PZT ceramics, its piezoelectric performance is still far behind. How to improve its piezoelectric response while maintaining its high phase transition temperature is an urgent problem that needs to be solved for BFO-based piezoelectric ceramic materials to become practical.

[0004] Summary of the Invention

[0005] In response to the problems existing in the prior art, the present invention provides a bismuth ferrite-based lead-free piezoelectric ceramic material and a preparation method thereof, which can effectively improve its sintering effect and ceramic quality, and achieve the improvement of its piezoelectric responsiveness while maintaining its high phase transition temperature.

[0006] The present invention is achieved through the following technical solutions:

[0007] A method for preparing a bismuth ferrite-based lead-free piezoelectric ceramic material comprises the following steps:

[0008] Step 1, grinding and mixing the raw materials in a molar ratio of Fe2O3:Bi2O3:TiO2:BaCO3:CuO:xLi2CO3=0.375:0.375:0.25:0.25:0.006:x, 0≤x≤0.9% to obtain an original mixed material;

[0009] Step 2: Pre-compressing the original mixture into tablets, sintering the pre-sintered samples, and then grinding, granulating, and tableting the pre-sintered samples to obtain tablet-formed samples;

[0010] Step 3: Heat the pressed sample to 500-600°C at a heating rate of 1-10°C / min, and keep it warm for debonding; then heat it to the target sintering temperature at a heating rate of 5°C / min-10°C / min, keep it warm for the set time, and then cool it to room temperature with the furnace to obtain a bismuth ferrite-based lead-free piezoelectric ceramic material.

[0011] Preferably, in step 2, during pre-tabletting, the pressure applied is 100 MPa-500 MPa.

[0012] Preferably, in step 2, the specific process of sintering is:

[0013] The pre-compressed sheet is placed in a high-temperature reaction furnace and heated to 700°C-950°C at a heating rate of 5°C / min-10°C / min and kept warm for 60min-200min to obtain a pre-sintered sample.

[0014] Preferably, in step 2, the tableting pressure is 500 MPa-800 MPa, and the target sintering temperature is 900° C.-1300° C.

[0015] Preferably, a binder is added during the granulation process in step 3 for grinding, wherein the binder is PVA.

[0016] Preferably, the insulation setting time in step 3 is 100min-300min.

[0017] Preferably, oxygen is introduced into the tablet-molded sample during sintering at high temperature.

[0018] A bismuth ferrite-based lead-free piezoelectric ceramic material has a chemical formula of 0.75BiFeO3-0.25BaTiO3-0.006CuO-xLi2O, where 0.0≤x≤0.9.

[0019] Preferably, the bismuth ferrite-based lead-free piezoelectric ceramic has a crystal phase structure of a perovskite phase.

[0020] Preferably, the bismuth ferrite-based lead-free piezoelectric ceramic has a dielectric constant of 275-372 at 1 MHz and an electrostrain of 0.09%-0.2% at 80 kV / cm.

[0021] Compared with the prior art, the present invention has the following beneficial technical effects:

[0022] The present invention provides a bismuth ferrite-based lead-free piezoelectric ceramic material and a preparation method thereof. Different from the traditional sintering process, the BiFeO3-BaTiO3-based ceramic material has poor crystallization performance, high sintering temperature, and low electrical performance. The MPB component 0.75BiFeO3-0.25BaTiO3 is co-doped with CuO and Li2CO3 to modify it, which significantly improves its crystallization performance and ceramic quality. The material has excellent multifunctionality, displays a saturated hysteresis loop, and has significant dielectric piezoelectric responsiveness. The preparation process of the present invention is simple, the raw materials are green and environmentally friendly, no lead-based raw materials are contained, the manufacturing cost is low, and the material is suitable for industrial mass production.

[0023] Furthermore, by optimizing the Li2CO3 content in the prepared BFBT-based modified ceramic material, significantly enhanced dielectric and piezoelectric properties were obtained. The dielectric constant at 1 MHz can reach 372, and the piezoelectric strain at an electric field of 80 kV / cm reaches 0.2%.

[0024] Furthermore, the modified bismuth ferrite-based lead-free piezoelectric ceramics have a pure perovskite phase structure, no obvious impurity phase, and a denser microstructure, which effectively improves the quality of the ceramics.

[0025] Furthermore, sintering in an oxygen atmosphere reduces the oxygen vacancy / Fe 2+ content, significantly reducing the large leakage conduction that has always existed in the system, thereby improving its breakdown field strength and ferroelectric properties. Under oxygen conditions, this reversible reaction is more likely to occur toward the left. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] FIG1 is a comparison of XRD patterns of samples of bismuth ferrite-based lead-free piezoelectric ceramic modified materials with x=0.0%, 0.2%, 0.5% and 0.9% prepared in Examples 1-4;

[0027] FIG2 is a scanning electron microscope (SEM) microscopic morphology of samples of the bismuth ferrite-based lead-free piezoelectric ceramic modified material prepared in Examples 1-4 with x=0.0%, 0.2%, 0.5% and 0.9%;

[0028] 3 is a room temperature dielectric spectrum of samples of bismuth ferrite-based lead-free piezoelectric ceramic modified materials prepared in Examples 1-4 with x=0.0%, 0.2%, 0.5% and 0.9%;

[0029] FIG4 is an electrostrain curve of samples of the bismuth ferrite-based lead-free piezoelectric ceramic modified material prepared in Examples 1-4 with x=0.0%, 0.2%, 0.5% and 0.9%;

[0030] FIG5 is a hysteresis loop of the bismuth ferrite-based lead-free piezoelectric ceramic modified material sample x=0.0 prepared in Example 1.

[0031] In the examples, the XRD test data were obtained using a PANalytical Empyrean X-ray diffractometer (copper K-alpha1), the SEM test data were obtained using a Japanese Hitachi TM3030Plus scanner, the room temperature dielectric spectrum was obtained using a Novocontrol Concept 40Alpha high-resolution dielectric spectrometer, and the hysteresis loop and electrostrain test data were obtained using a TF Analyzer2000 ferroelectric and piezoelectric testing system equipped with an MTI laser deformation tester. DETAILED DESCRIPTION

[0032] The present invention will be further described in detail below with reference to specific embodiments, which are intended to explain the present invention rather than to limit it.

[0033] In order to enable those skilled in the art to better understand the solutions of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts should fall within the scope of protection of the present invention.

[0034] A bismuth ferrite-based lead-free piezoelectric ceramic material and a modification method thereof, comprising the following steps:

[0035] Step 1, weighing the required raw materials according to the stoichiometric ratio, the molar ratio of each raw material is: Fe2O3:Bi2O3:TiO2:BaCO3:CuO:xLi2CO3=0.375:0.375:0.25:0.25:0.006:x, 0≤x≤0.9%, and mixing the raw materials thoroughly and grinding them into a smaller particle size to obtain a raw material;

[0036] Step 2: The mixed raw material obtained in step 1 is pre-pressed in a mold at a pressure of 100 MPa-500 MPa, and then placed in a high-temperature reactor and heated to 700°C-950°C for pre-sintering at a heating rate of up to 5°C / min-10°C / min, and kept warm for 60min-200min to obtain a pre-sintered sample;

[0037] Step 3: The pre-sintered sample obtained in step 2 is placed in a mortar and ground into a powder of suitable particle size for a second time. A binder such as PVA is added for granulation, and the powder is pressed into a tablet in a mold at a pressure of 500 MPa-800 MPa to obtain a tablet-shaped sample;

[0038] Step 4: Place the pressed tablet sample obtained in step 3 into a high-temperature reaction furnace, first heat it to 500°C at a heating rate of 1-10°C / min, and keep it warm for 30 minutes to remove adhesive; then use a higher heating rate of 5-10°C / min to quickly heat it to the target sintering temperature of 900°C-1300°C, while passing oxygen into the furnace and keeping it warm for 100 minutes-300 minutes; finally, cool it to room temperature with the furnace to obtain the target ceramic sample.

[0039] A Li- / Cu-co-modified BiFeO3-BaTiO3-based functional ceramic material prepared by a solid-state sintering process. The ceramic chemical composition is 0.75BiFeO3-0.25BaTiO3-0.006CuO-xLi2O, 0.0≤x≤0.9%, and the ceramic crystal phase structure is a pure perovskite phase. It has excellent multifunctionality, displays a saturated hysteresis loop, and has a significant dielectric piezoelectric response.

[0040] Example 1

[0041] A Li- / Cu-co-doped 0.75BiFeO3-0.25BaTiO3 functional ceramic material prepared by a solid-state sintering process, with a chemical composition of 0.75BiFeO3-0.25BaTiO3-0.006CuO, referred to as 1#. The process includes the following steps:

[0042] Step 1: Weigh the required raw materials according to the stoichiometric ratio: the molar ratio of each raw material is: Fe2O3:Bi2O3:TiO2:BaCO3:CuO=0.375:0.375:0.25:0.25:0.006, mix the raw materials thoroughly and grind them to obtain the original material.

[0043] Step 2: The uniformly mixed raw material obtained in step 1 is pre-pressed in a mold at a pressure of 100 MPa, then placed in a high-temperature reactor and heated to 700°C at a heating rate of 8°C / min and kept warm for 200 minutes for pre-sintering to obtain a pre-sintered sample.

[0044] Step 3: Place the pre-sintered sample obtained in step 2 in a mortar and grind it into powder of appropriate particle size for a second time, then add a binder such as PVA for granulation, and then press and shape it in a mold at a pressure of 500 MPa to obtain a pressed sample.

[0045] Step 4: Place the pressed tablet sample obtained in step 3 into a high-temperature reactor, first heat it to 500°C at a heating rate of 1°C / min, and then keep it warm for 30 minutes to remove adhesive; then use a higher heating rate of 10°C / min to heat it to the target sintering temperature of 1100°C, while passing oxygen into the high-temperature reactor and keeping it warm for 120 minutes; finally cool it to room temperature with the furnace to obtain the target 1# ceramic sample.

[0046] As can be seen from Figure 1, the modified ceramic has a pure perovskite phase structure with no obvious impurities. As shown in Figure 2, the sample has a relatively dense microstructure with an average grain size of about 2-3 microns. The dielectric spectrum and electrostrain are shown in Figures 3 and 4, respectively. The dielectric constant is 308 at 1MHz and the electrostrain is 0.13% at 80kV / cm. A saturated hysteresis loop was obtained, confirming the excellent ferroelectricity of the material, with a residual polarization strength of approximately 40μC / cm. 2 , as shown in Figure 5.

[0047] Example 2

[0048] A Li- / Cu-codoped 0.75BiFeO3-0.25BaTiO3 functional ceramic material prepared by a solid-state sintering process, with a chemical composition of 0.75BiFeO3-0.25BaTiO3-0.006CuO-0.002Li2CO3, referred to as 2#. The process includes the following steps:

[0049] Step 1: Weigh the required raw materials according to the stoichiometric ratio: the molar ratio of each raw material is: Fe2O3:Bi2O3:TiO2:BaCO3:CuO:Li2CO3=0.375:0.375:0.25:0.25:0.006:0.002, mix the raw materials thoroughly and grind them to obtain the original material.

[0050] Step 2: The uniformly mixed raw material obtained in step 1 is pre-pressed in a mold at a pressure of 100 MPa, then placed in a high-temperature reactor and heated to 700°C at a heating rate of 8°C / min and kept warm for 200 minutes for pre-sintering to obtain a pre-sintered sample.

[0051] Step 3: Place the pre-sintered sample obtained in step 2 in a mortar and grind it into powder of appropriate particle size for a second time, then add a binder such as PVA for granulation, and then press and shape it in a mold at a pressure of 500 MPa to obtain a pressed sample.

[0052] Step 4: Place the pressed sample obtained in step 3 into a high-temperature reactor, first heat it to 500°C at a heating rate of 1°C / min, and then keep it warm for 30 minutes to remove adhesive; then use a higher heating rate of 10°C / min to heat it to the target sintering temperature of 1050°C, while passing oxygen into the high-temperature reactor and keeping it warm for 120 minutes; finally cool it to room temperature with the furnace to obtain the target 2# ceramic sample.

[0053] As can be seen in Figure 1, the modified ceramic exhibits a pure perovskite phase structure, with no apparent impurities. As shown in Figure 2, the sample exhibits a dense microstructure with an average grain size of approximately 10 microns. The dielectric spectrum and electrostrain are shown in Figures 3 and 4, respectively. The dielectric constant is 325 at 1 MHz, and the electrostrain is 0.09% at 80 kV / cm.

[0054] Example 3

[0055] A Li- / Cu-co-doped 0.75BiFeO3-0.25BaTiO3 functional ceramic material prepared by a solid-state sintering process, with a chemical composition of 0.75BiFeO3-0.25BaTiO3-0.006CuO-0.005Li2CO3, referred to as 3#. The process includes the following steps:

[0056] Step 1: Weigh the required raw materials according to the stoichiometric ratio: the molar ratio of each raw material is: Fe2O3:Bi2O3:TiO2:BaCO3:CuO:Li2CO3=0.375:0.375:0.25:0.25:0.006:0.005, mix the raw materials thoroughly and grind them to obtain the original material.

[0057] Step 2: The uniformly mixed raw material obtained in step 1 is pre-pressed in a mold at a pressure of 100 MPa, then placed in a high-temperature reactor and heated to 700°C at a heating rate of 5°C / min and kept warm for 200 minutes for pre-sintering to obtain a pre-sintered sample.

[0058] Step 3: Place the pre-sintered sample obtained in step 2 in a mortar and grind it into powder of appropriate particle size for a second time, then add a binder such as PVA for granulation, and then press and shape it in a mold at a pressure of 500 MPa to obtain a pressed sample.

[0059] Step 4: Place the pressed sample obtained in step 3 into a high-temperature reactor, first heat it to 500°C at a heating rate of 1°C / min, and then keep it warm for 30 minutes to remove adhesive; then use a higher heating rate of 10°C / min to heat it to the target sintering temperature of 1000°C, while passing oxygen into the high-temperature reactor and keeping it warm for 120 minutes; finally cool it to room temperature with the furnace to obtain the target 3# ceramic sample.

[0060] As shown in Figure 1, the modified ceramic exhibits a pure perovskite phase structure, with no apparent impurities. As shown in Figure 2, the sample exhibits a dense microstructure with an average grain size of approximately 10 microns. The dielectric spectrum and electrostrain are shown in Figures 3 and 4, respectively. The dielectric constant is 372 at 1 MHz, and the electrostrain is 0.12% at 80 kV / cm.

[0061] Example 4

[0062] A Li- / Cu-co-doped 0.75BiFeO3-0.25BaTiO3 functional ceramic material prepared by a solid-state sintering process, with a chemical composition of 0.75BiFeO3-0.25BaTiO3-0.006CuO-0.009Li2CO3, referred to as 4#. The process includes the following steps:

[0063] Step 1: Weigh the required raw materials according to the stoichiometric ratio: the molar ratio of each raw material is: Fe2O3:Bi2O3:TiO2:BaCO3:CuO:Li2CO3=0.375:0.375:0.25:0.25:0.006:0.009, mix the raw materials thoroughly and grind them to obtain the original material.

[0064] Step 2: The uniformly mixed raw material obtained in step 1 is pre-pressed in a mold at a pressure of 100 MPa, and then placed in a high-temperature reactor and heated to 700°C at a heating rate of 10°C / min and kept warm for 200 minutes for pre-sintering to obtain a pre-sintered sample.

[0065] Step 3: Place the pre-sintered sample obtained in step 2 in a mortar and grind it into powder of appropriate particle size for a second time, then add a binder such as PVA for granulation, and then press and shape it in a mold at a pressure of 500 MPa to obtain a pressed sample.

[0066] Step 4: Place the pressed sample obtained in step 3 into a high-temperature reactor, first heat it to 500°C at a heating rate of 1°C / min, and then keep it warm for 30 minutes to remove adhesive; then use a higher heating rate of 10°C / min to heat it to the target sintering temperature of 1050°C, while passing oxygen into the high-temperature reactor and keeping it warm for 120 minutes; finally cool it to room temperature with the furnace to obtain the target 4# ceramic sample.

[0067] As can be seen in Figure 1, the modified ceramic exhibits a pure perovskite phase structure, with no apparent impurities. As shown in Figure 2, the sample exhibits a dense microstructure with an average grain size of approximately 10 microns. The dielectric spectrum and electrostrain are shown in Figures 3 and 4, respectively. The dielectric constant is 275 at 1 MHz, and the electrostrain is 0.2% at 80 kV / cm.

[0068] Example 5

[0069] A Li- / Cu-co-doped 0.75BiFeO3-0.25BaTiO3 functional ceramic material prepared by a solid-state sintering process, with a chemical composition of 0.75BiFeO3-0.25BaTiO3-0.006CuO-0.007Li2CO3, referred to as 4#. The process includes the following steps:

[0070] Step 1: Weigh the required raw materials according to the stoichiometric ratio: the molar ratio of each raw material is: Fe2O3:Bi2O3:TiO2:BaCO3:CuO:Li2CO3=0.375:0.375:0.25:0.25:0.006:0.007, mix the raw materials thoroughly and grind them to obtain the original material.

[0071] Step 2: The uniformly mixed raw material obtained in step 1 is pre-pressed in a mold at a pressure of 300 MPa, then placed in a high-temperature reactor and heated to 850°C at a heating rate of 8°C / min and kept warm for 150 minutes for pre-sintering to obtain a pre-sintered sample.

[0072] Step 3: Place the pre-sintered sample obtained in step 2 in a mortar and grind it into a powder of appropriate particle size for a second time, then add a binder such as PVA to granulate it, and then press it into a tablet in a mold at a pressure of 650 MPa to obtain a tablet-molded sample.

[0073] Step 4: Place the pressed sample obtained in step 3 into a high-temperature reactor, first heat it to 550°C at a heating rate of 3°C / min, and then keep it warm for 30 minutes to remove adhesive; then use a higher heating rate of 8°C / min to heat it to the target sintering temperature of 1150°C, while passing oxygen into the high-temperature reactor and keeping it warm for 120 minutes; finally cool it to room temperature with the furnace to obtain the target 5# ceramic sample.

[0074] The above content is only for explaining the technical idea of ​​the present invention and cannot be used to limit the protection scope of the present invention. Any changes made on the basis of the technical solution in accordance with the technical idea proposed by the present invention shall fall within the protection scope of the claims of the present invention.

[0075] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any form. Any ordinary technician in this industry can smoothly implement the present invention as shown in the drawings and described above. However, any equivalent changes, modifications and evolutions made by technicians familiar with this profession without departing from the scope of the technical solution of the present invention using the technical content disclosed above are all equivalent embodiments of the present invention. At the same time, any equivalent changes, modifications and evolutions made to the above embodiments based on the essential technology of the present invention are still within the scope of protection of the technical solution of the present invention.

Claims

1. A method for preparing a bismuth ferrite-based lead-free piezoelectric ceramic material, characterized in that: The following steps are involved: Step 1, mixing and grinding the raw materials in a molar ratio of Fe2O3:Bi2O3:TiO2:BaCO3:CuO:xLi2CO3=0.375:0.375:0.25:0.25:0.006:x, 0≤x≤0.9% to obtain an original mixed material; Step 2, preparing a pre-compressed tablet from the original mixed material, sintering to obtain a pre-sintered sample, and then grinding, granulating and compressing the pre-sintered sample to obtain a compressed sample; Step 3, heat the pressed sample to 500℃-600℃ at a heating rate of 1-10℃ / min, and keep it warm for debonding; then heat it to the target sintering temperature at a heating rate of 5℃ / min-10℃ / min, keep it warm for the set time, and then cool it to room temperature with the furnace to obtain bismuth ferrite-based lead-free piezoelectric ceramic material.

2. The method for preparing a bismuth ferrite-based lead-free piezoelectric ceramic material according to claim 1, characterized in that: In the step 2, during the pre-tabletting, the pressure applied is 100 MPa-500 MPa.

3. The method for preparing a bismuth ferrite-based lead-free piezoelectric ceramic material according to claim 1, characterized in that: In step 2, the specific process of sintering is: The pre-pressed sheet is placed in a high-temperature reaction furnace and heated to 700°C-950°C at a heating rate of 5°C / min-10°C / min and kept warm for 60min-200min to obtain a pre-sintered sample.

4. The method for preparing a bismuth ferrite-based lead-free piezoelectric ceramic material according to claim 1, characterized in that: In step 2, the tableting pressure is 500MPa-800Mpa, and the target sintering temperature is 900°C-1300°C.

5. The method for preparing a bismuth ferrite-based lead-free piezoelectric ceramic material according to claim 1, characterized in that: In the granulation process in step 3, a binder is added for grinding, wherein the binder is PVA.

6. The method for preparing a bismuth ferrite-based lead-free piezoelectric ceramic material according to claim 1, characterized in that: The insulation setting time in step 3 is 100min-300min.

7. The method for preparing a bismuth ferrite-based lead-free piezoelectric ceramic material according to claim 1, characterized in that: Oxygen is used as the gas introduced when the tablet-forming sample is sintered at high temperature.

8. A bismuth ferrite-based lead-free piezoelectric ceramic material, prepared by the preparation method according to any one of claims 1 to 7, characterized in that: The chemical formula of the bismuth ferrite-based lead-free piezoelectric ceramic is 0.75BiFeO3-0.25BaTiO3-0.006CuO-xLi2O, 0.0≤x≤0.

9.

9. The bismuth ferrite-based lead-free piezoelectric ceramic material according to claim 8, characterized in that: The bismuth ferrite-based lead-free piezoelectric ceramic has a crystal phase structure of a perovskite phase.

10. The bismuth ferrite-based lead-free piezoelectric ceramic material according to claim 8, characterized in that: The bismuth ferrite-based lead-free piezoelectric ceramic has a dielectric constant of 275-372 at 1 MHz and an electro-induced strain of 0.09%-0.2% at 80 kV / cm.

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