Lead-free relaxor ferroelectric solid solution and method of making same

Abstract

The application provides a lead-free relaxor ferroelectric solid solution and a preparation method thereof. The chemical composition of the lead-free relaxor ferroelectric solid solution is 0.9((1-x)BaTi 0.8 Zr 0.2 O3-xBa 0.65 Sr 0.35 TiO3)-0.1BaTiO3-y% MgO, wherein x represents a molar coefficient, y represents a mass fraction, 0.2<=x<=0.8, and 0 In the application, BZT, BST and BT ferroelectric bodies are combined, the BT ferroelectric body with high polarization intensity is introduced to improve the polarization behavior of the ceramic, and the electric calorimetric variation, the energy storage density and the pyroelectric current of the system are significantly improved; the MgO nano powder is introduced at the interface of the ternary combined lead-free relaxor ferroelectric solid solution, a barrier layer can be formed and an electric field amplification effect can be generated, so that the breakdown field strength is increased, and the electric calorimetry and the energy storage characteristics are improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of relaxor ferroelectric materials, and particularly relates to a lead-free relaxor ferroelectric solid solution and a preparation method thereof. BACKGROUND

[0002] Dielectric materials are important basic materials in the field of high-tech and national defense construction. Lead-free relaxor ferroelectric materials are important multifunctional dielectric materials due to environmental protection and excellent polarization characteristics. In the field of electrocaloric refrigeration, lead-free relaxor ferroelectric materials are the most promising electrocaloric materials that can balance ΔT and δTFWHM near room temperature due to the existence of multiple polarization phases. Lead-free relaxor ferroelectric materials are also considered to be the most promising energy storage materials due to high saturation polarization and low remanent polarization. In addition, lead-free relaxor ferroelectric materials have a wide application prospect in pyroelectricity due to the unique polar nanoregions, which can break the long-range order of ferroelectric domains and improve the pyroelectric coefficient of ceramics.

[0003] BaTiO3(BT)-based lead-free relaxor ferroelectric materials have been studied in the fields of electrocaloric, energy storage and pyroelectricity. Chinese patent CN107778004B discloses a barium strontium zirconium titanate ceramic having a general formula shown in formula I: Ba (1-x) Sr x Zr y Ti (1-y) O3 formula I; in formula I, x is 0.15-0.30; y is 0.15-0.2. The domain structure is changed from macrodomain to microdomain by doping zirconium ions, thereby widening the phase transition temperature range. The proportion of macrodomains in the ceramic structure is increased by doping strontium ions, so as to improve the polarization strength and corresponding electrocaloric effect indicators such as adiabatic temperature change.

[0004] However, the above technical solution still has the following disadvantages: the lead-free relaxor ferroelectric material formed by doping zirconium ions and strontium ions has high saturation polarization and low remanent polarization, thereby affecting the polarization behavior of the ceramic and causing problems such as low breakdown field strength, low energy storage density and poor fatigue characteristics. SUMMARY

[0005] Therefore, the present application provides a lead-free relaxor ferroelectric solid solution that has excellent electrocaloric and energy storage properties near room temperature.

[0006] The technical solution of the present application is implemented as follows: the present application provides a lead-free relaxor ferroelectric solid solution, which has a chemical composition of 0.9((1-x)BaTi 0.8 Zr 0.2 O3-xBa 0.65 Sr 0.35TiO3)-0.1BaTiO3-y%MgO, wherein x and y represent molar coefficients respectively, 0.2≤x≤0.8, 0

[0007] In the present application, by introducing two kinds of temperature complementary relaxor ferroelectrics Ba 0.65 Sr 0.35 TiO3(BST) base and BaTi 0.8 Zr 0.2 O3(BZT) base, wherein the temperature window of BST is -20-50 DEG C, the temperature window of BZT is 45-85 DEG C, the two kinds of relaxor ferroelectrics are compounded, the working temperature range of lead-free relaxor ferroelectric solid solution can be widened, the Curie temperature of lead-free relaxor ferroelectric solid solution can be adjusted in a large range near room temperature, the polarization and persistence characteristics of the system are further enhanced, lead-free relaxor ferroelectric solid solution with large electrocaloric temperature and high energy storage density can be obtained, and the pyroelectric coefficient of the ceramic is also improved due to the introduction of BST and BZT which both have nano polarity micro area, the long-range order of ferroelectric domain is broken.

[0008] In the present application, BT ferroelectric with high strength is introduced to synergistically improve the polarization behavior of the ceramic, and the electrocaloric temperature change, energy storage density and pyroelectric current of the system are significantly improved; MgO nano powder is introduced at the interface of the ternary composite lead-free relaxor ferroelectric solid solution of BZT-BST-BT, because the dielectric constant of BZT-BST-BT is large and the breakdown field strength is small, and the dielectric constant of MgO is small and the breakdown field strength is large, according to the series connection model and interface theory, the combination of the two can form a blocking layer and produce an electric field amplification effect, so that the breakdown field strength is increased, and the electrocaloric and energy storage characteristics are improved.

[0009] On the basis of the above technical scheme, preferably, x is 0.3 and y is 0.3.

[0010] Specifically, when x is 0.3 and y is 0.3, the performance of the lead-free relaxor ferroelectric solid solution is better.

[0011] The present application provides a preparation method of the lead-free relaxor ferroelectric solid solution described in the above technical scheme, comprising the following steps:

[0012] S1, BaCO3, TiO2 and ZrO2 are configured according to the stoichiometric ratio of BaTi 0.8 Zr 0.2 O3 to obtain a first ceramic powder, BaCO3, SrCO3 and TiO2 are configured according to the stoichiometric ratio of Ba 0.65 Sr 0.35 TiO3 to obtain a second ceramic powder, and BaCO3 and TiO2 are configured according to the stoichiometric ratio to obtain a third ceramic powder.

[0013] S2, the ceramic powders are respectively ball milled once, and the mixed ceramic powders are pre-fired;

[0014] S3, the first ceramic powder, the second ceramic powder and the third ceramic powder after pre-firing are configured according to the stoichiometric ratio of 0.9((1-x)BaTi 0.8 Zr 0.2 O3-xBa 0.65 Sr 0.35 TiO3)-0.1BaTiO3, and MgO nano-powder is doped, and then the second ball milling is performed, and then the ceramic green body is prepared through drying, sieving, granulation and dry pressing;

[0015] S4, the ceramic green body is sintered, and the relaxor ferroelectric solid solution is obtained after the sintering is completed and the furnace is cooled down.

[0016] In the application, the stoichiometric ratio of the first ceramic powder, the second ceramic powder and the third ceramic powder is 0.9(1-x):0.9x:0.1, and the value range of x and y is consistent with the value range of x and y in the above technical solution, which will not be repeated here.

[0017] In the application, the lead-free relaxor ferroelectric solid solution is prepared by a ternary solid solution method, that is, BZT, BST and BT ceramic powders are configured respectively and pre-fired to promote the reaction of raw materials and generate BZT solid solution, BST solid solution and BT solid solution, and then the BZT-BST-BT solid solution is configured according to the stoichiometric ratio to promote the full combination of BT ferroelectric and BZT-BST, and promote the synergistic improvement of the polarization behavior of the ceramic, and further improve the electric card and energy storage characteristics of the system.

[0018] On the basis of the above technical solution, preferably, the doping ratio of the MgO nano-powder in the step S2 is less than or equal to 0.5% of the total mass of the first ceramic powder, the second ceramic powder and the third ceramic powder.

[0019] In the application, the doping of a certain proportion of MgO nano-powder can achieve the effect of synergistically improving the polarization behavior of the ceramic, and when the doping amount is too small, it is difficult to better realize the effect, and when the doping amount is too large, the MgO nano-powder cannot be solid-solved into the grain interior, causing the sintering characteristics to change and the ceramic structure to be not dense.

[0020] More preferably, the particle size of the MgO nano-powder is 80-120 nm.

[0021] In the application, by limiting the particle size of the MgO nano-powder to 80-120 nm, the MgO particles can more uniformly and easily enter the ceramic grain boundary and maintain good insulation characteristics.

[0022] On the basis of the above technical scheme, preferably, in the step S2, the agate ball mass, the ball milling solvent mass and the powder mass are ball milled once according to a mass ratio of (1.4-2.2):1:(0.45-0.58), the solvent for the once ball milling is ethanol, and the time for the once ball milling is 2-6h, wherein the powder mass is the total mass of the first ceramic powder, the second ceramic powder and the third ceramic powder.

[0023] On the basis of the above technical scheme, preferably, in the step S2, the pre-burning temperature is 100-1300℃, and the pre-burning time is 2-6h.

[0024] On the basis of the above technical scheme, preferably, in the step S3, the drying temperature is 60-75℃, and the drying time is 1-6h.

[0025] On the basis of the above technical scheme, preferably, in the step S3, the sieving particle size is 200 mesh.

[0026] On the basis of the above technical scheme, preferably, in the step S3, 5%-20% of polyvinyl alcohol solution is added during the granulation, the polyvinyl alcohol solution is added in an amount of 10-20% of the powder mass, and is fully mixed and uniformly distributed in a mortar.

[0027] In the present application, the polyvinyl alcohol can play the role of an adhesive, can completely fill in the gaps of the particles, and the polyvinyl alcohol also has gas blocking property, so that the addition of 5%-20% of polyvinyl alcohol solution during the granulation can improve the compactness of the ceramic structure and reduce the porosity.

[0028] On the basis of the above technical scheme, preferably, in the step S4, the sintering of the ceramic green body specifically comprises the following steps:

[0029] S401, heating the ceramic green body to 550-600℃, and keeping the temperature for 30-45min;

[0030] S402, continuously heating the heated ceramic green body to 1200-1500℃, and keeping the temperature for 3-8h,

[0031] The heating rate in the step S401 and the step S402 is 2-10℃ / min.

[0032] The lead-free relaxor ferroelectric solid solution of the present application has the following beneficial effects relative to the prior art:

[0033] (1) the present application is by setting BZT, BST and BT ferroelectric ternary composite, wherein BZT and BST ceramic material is curie temperature near room temperature of lead-free relaxor ferroelectric material, both composite can obtain a wide range of curie temperature near room temperature, while BZT and BST constitute the lead-free relaxor ferroelectric has high saturation polarization and low remanent polarization, the introduction of high polarization BT ferroelectric to synergistically enhance the polarization behavior of ceramic, significantly improve the system of electric card temperature, energy density and pyroelectric current;

[0034] (2) the present application is by introducing MgO nano powder at the interface of BZT, BST and BT ternary composite lead-free relaxor ferroelectric solid solution, because the dielectric constant of BZT-BST-BT is large, the breakdown field is small, and the dielectric constant of MgO is small, the breakdown field is large, according to the series model and interface theory, the combination of the two can form a barrier layer and produce electric field amplification effect, so that the breakdown field is increased, and the electric card and energy storage characteristics are improved;

[0035] (3) the present application is prepared by ternary solid solution method, that is, BZT, BST and BT ceramic powder are prepared respectively, then BZT-BST-BT solid solution is prepared, and MgO nano powder is doped, so that the curie temperature can be adjusted near room temperature and large polarization can be obtained. BRIEF DESCRIPTION OF DRAWINGS

[0036] In order to more clearly illustrate the technical solutions of the embodiments of the present application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or prior art description, obviously, the drawings in the following description are only some embodiments of the present application, and those skilled in the art can also obtain other drawings according to these drawings without creating any creative labor.

[0037] Figure 1 XRD diagram of the lead-free relaxor ferroelectric solid solution prepared in embodiments one to five of the present application;

[0038] Figure 2 SEM diagram of the lead-free relaxor ferroelectric solid solution prepared in embodiments one to five of the present application;

[0039] Figure 3 Electric hysteresis loop of the multifunctional lead-free relaxor ferroelectric solid solution corresponding to embodiments one to five of the present application;

[0040] Figure 4 Electric card effect diagram of the multifunctional lead-free relaxor ferroelectric solid solution corresponding to embodiments one to five of the present application;

[0041] Figure 5 Fatigue characteristic diagram of the multifunctional lead-free relaxor ferroelectric solid solution corresponding to embodiments one to five of the present application;

[0042] Figure 6 Pyroelectric coefficient diagram of the multifunctional lead-free relaxor ferroelectric solid solution corresponding to embodiments one to five. DETAILED DESCRIPTION

[0043] The technical solutions in the embodiments of the present application will be clearly and completely described in combination with the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work belong to the protection scope of the present application.

[0044] The raw materials used in the following embodiments are all commercially available.

[0045] Embodiment one

[0046] The present embodiment provides a lead-free relaxor ferroelectric solid solution, which has a chemical composition of 0.63BaTi 0.8 Zr 0.2 O3-0.27Ba 0.65 Sr 0.35 TiO3-0.1BaTiO3-0.3%MgO(x=0.3,y=0.3).

[0047] Step 1: 0.05 mol of initial powder BaCO3(9.867 g), ZrO2(1.232 g) and TiO2(3.195 g) were weighed according to the stoichiometric ratio of BaTi 0.8 Zr 0.2 O3; 0.05 mol of initial powder BaCO3(6.413 g), SrCO3(2.584 g) and TiO2(3.993 g) were weighed according to the stoichiometric ratio of Ba 0.65 Sr 0.35 TiO3; and finally, 0.05 mol of initial powder BaCO3(9.867 g) and TiO2(3.993 g) were weighed according to the stoichiometric ratio of BaTiO3. The above three powders were respectively subjected to wet ball milling, and the mass ratio of agate ball, ball milling solvent and ball milling raw material was 5:4:1, the ball milling solvent was ethanol, and the ball milling time was 4 hours.

[0048] Step 2: After the slurry obtained by ball milling was dried at 75°C, ceramic powder was obtained by pre-sintering at 1150°C for 4 hours.

[0049] Step 3: 0.05 mol of initial powder BaCO3(9.867 g), ZrO2(1.232 g) and TiO2(3.195 g) were weighed according to the stoichiometric ratio of BaTi 0.8 Zr 0.2 O3-0.27Ba 0.65 Sr 0.35TiO3-0.1BaTiO3 stoichiometric ratio of 0.05 mol of BaTi 0.8 Zr 0.2 O3(7.616g), Ba 0.65 Sr 0.35 TiO3(2.913g) and BaTiO3(1.165g) raw materials were configured. In accordance with the proportion of ingredients, 0.3% of MgO nano-powder was added by mass ratio, wet ball milling was adopted, and ceramic powder was obtained after drying and sieving.

[0050] Step 4: 8% of polyvinyl alcohol solution was added to the powder of step 3, and the amount of addition was 10% of the mass of the ceramic powder.

[0051] Step 5: The step 4 was dry pressed by a mold, the molding pressure was 2Mpa, and the molding time was 30 seconds.

[0052] Step 6: The green sheet obtained in step 5 was sintered, the temperature was raised to 550℃ at a rate of 3℃ / min and kept for 30 minutes, then the temperature was raised to 1300℃ and kept for 4 hours, and the furnace was cooled down. 0.63BaTi 0.8 Zr 0.2 O3-0.27Ba 0.65 Sr 0.35 TiO3-0.1BaTiO3-0.3% MgO multifunctional relaxor ferroelectric solid solution.

[0053] Step 7: The XRD of the obtained sample is shown in Figure 1 , and the SEM is shown in Figure 2 . The ceramic sheet of step 5 was polished to a thickness of less than 0.2mm, and silver paste was screen printed on the upper and lower surfaces of the ceramic, then sintered at 550℃ for 30min and cooled in the furnace to obtain silver electrodes. The sample was polarized at room temperature under an electric field of 50kV / cm for 30min, and the pyroelectric coefficient of the sample was tested. As shown in Figures 3-6 , the breakdown field strength of the obtained sample was 100kV / cm, the room temperature electrocaloric temperature change was 0.8K, the working temperature window was 45℃, the energy storage density was 0.75J / cm 3 , and the pyroelectric coefficient reached 60×10 -4 Cm -2 ℃ -1 . After 1000 cycles of electrocaloric test, the attenuation was less than 1%.

[0054] Example Two

[0055] This example provides a lead-free relaxor ferroelectric solid solution, which has a chemical composition of 0.63BaTi 0.8 Zr 0.2 O3-0.27Ba 0.65Sr 0.35 TiO3-0.1BaTiO3-0.3%MgO(x=0.2, y=0.3).

[0056] Step 1: according to the stoichiometric ratio of 0.63BaTi 0.8 Zr 0.2 O3stoichiometric ratio of 0.05 mol of initial powder BaCO3(9.867 g), ZrO2(1.232 g) and TiO2(3.195 g) were weighed; according to the stoichiometric ratio of 0.63BaTi 0.65 Sr 0.35 TiO3stoichiometric ratio of 0.05 mol of initial powder BaCO3(6.413 g), SrCO3(2.584 g) and TiO2(3.993 g) were weighed; finally, according to the stoichiometric ratio of 0.63BaTiO3, 0.05 mol of initial powder BaCO3(9.867 g) and TiO2(3.993 g) were weighed. The above three powders were respectively subjected to wet ball milling, the mass ratio of agate ball, ball milling solvent and ball milling raw material was 5:4:1, the ball milling solvent was ethanol, and the ball milling time was 4 hours.

[0057] Step 2: after the slurry obtained by ball milling was dried at 75℃, ceramic powder was obtained by pre-sintering at 1150℃ for 4 hours.

[0058] Step 3: according to the stoichiometric ratio of 0.63BaTi 0.8 Zr 0.2 O3-0.27Ba 0.65 Sr 0.35 TiO3-0.1BaTiO3stoichiometric ratio of 0.05 mol of required BaTi 0.8 Zr 0.2 O3(7.616 g), Ba 0.65 Sr 0.35 TiO3(2.913 g) and BaTiO3(1.165 g) raw materials were configured. According to the proportioning ratio, MgO nano-powder was added in a mass ratio of 0.3%, wet ball milling was adopted, and ceramic powder was obtained after drying and sieving.

[0059] Step 4: 8% polyvinyl alcohol solution was added to the powder of step 3, and the amount of addition was 10% of the mass of the ceramic powder.

[0060] Step 5: the green compact of step 4 was dry-pressed by a mold, the molding pressure was 2 MPa, and the molding time was 30 seconds.

[0061] Step 6: the green compact sheet obtained in step 5 was sintered, the temperature was raised to 550℃ at a rate of 3℃ / min and kept for 30 minutes, then the temperature was raised to 1300℃ and kept for 4 hours, and the furnace was cooled down. Thus, 0.63BaTi 0.8 Zr 0.2O3-0.27Ba 0.65 Sr 0.35 TiO3-0.1BaTiO3-0.3%MgO multi-functional relaxor ferroelectric solid solution.

[0062] Step 7: The XRD of the obtained sample is shown in Figure 1 , and the SEM is shown in Figure 2 . The ceramic sheet of step 6 is polished to a thickness of 0.2 mm, and a medium temperature silver paste is screen-printed on the upper and lower surfaces of the ceramic. After being baked at 550°C for 30 min, the sample is cooled in the furnace to obtain silver electrodes. The sample is polarized at room temperature for 30 min under an electric field of 30 kV / cm, and the pyroelectric coefficient of the sample is tested. As shown in Figures 3-6 , the breakdown field strength of the obtained sample is 85 kV / cm, the room temperature electrocaloric temperature change is 0.7 K, the working temperature window is 40°C, and the energy storage density is 0.14 J / cm 3 , and the pyroelectric coefficient reaches 39×10 -4 Cm -2 C- 1 . After 1000 cycles of electrocaloric test, the attenuation is 1%.

[0063] Example Three

[0064] This example provides a lead-free relaxor ferroelectric solid solution, which has a chemical composition of 0.18BaTi 0.8 Zr 0.2 O3-0.72Ba 0.65 Sr 0.35 TiO3-0.1BaTiO3-0.3%MgO (x=0.8, y=0.3).

[0065] Step 1: 0.05 mol of initial powder BaCO3(9.867 g), ZrO2(1.232 g), and TiO2(3.195 g) are weighed according to the stoichiometric ratio of BaTi 0.8 Zr 0.2 O3. 0.65 Sr 0.35 TiO3, 0.05 mol of initial powder BaCO3(6.413 g), SrCO3(2.584 g), and TiO2(3.993 g) are weighed according to the stoichiometric ratio of BaTiO3, and finally 0.05 mol of initial powder BaCO3(9.867 g) and TiO2(3.993 g) are weighed according to the stoichiometric ratio of BaTiO3. The above three powders are respectively subjected to wet ball milling, and the mass ratio of agate ball, ball milling solvent, and ball milling raw material is 5:4:1. The ball milling solvent is ethanol, and the ball milling time is 4 hours.

[0066] Step 2: After the slurry obtained by ball milling is dried at 75°C, ceramic powder is obtained by pre-sintering at 1150°C for 4 hours.

[0067] Step 3: 0.18BaTi 0.8 Zr 0.2 O3-0.72Ba 0.65 Sr 0.35 TiO3-0.1BaTiO3 stoichiometric ratio of 0.05 mol of the required BaTi 0.8 Zr 0.2 O3(2.177g), Ba 0.65 Sr 0.35 TiO3(7.769g) and BaTiO3(1.165g) raw materials were prepared. According to the proportion of ingredients, MgO nano-powder was added in a mass ratio of 0.3%, and ceramic powder was obtained after drying and sieving by wet ball milling.

[0068] Step 4: 8% polyvinyl alcohol solution was added to the powder of step 3, and the amount added was 10% of the mass of the ceramic powder.

[0069] Step 5: The step 4 was dry pressed by mold, the molding pressure was 2Mpa, and the molding time was 30 seconds.

[0070] Step 6: The green sheet obtained in step 5 was sintered, and the temperature was raised to 550℃ at a rate of 3℃ / min and kept for 30 minutes, then raised to 1300℃ and kept for 4 hours, and then cooled in the furnace to obtain 0.18BaTi 0.8 Zr 0.2 O3-0.72Ba 0.65 Sr 0.35 TiO3-0.1BaTiO3-0.3% MgO multifunctional relaxor ferroelectric solid solution.

[0071] Step 7: The XRD of the obtained sample is shown in Figure 1 , and the SEM is shown in Figure 2 . The ceramic sheet of step 6 was polished to a thickness of 0.2mm, and silver paste was screen printed on the upper and lower surfaces of the ceramic, and then sintered at 550℃ for 30min and cooled in the furnace to obtain silver electrodes. The sample was polarized at room temperature under an electric field of 30kV / cm for 30min, and the pyroelectric coefficient of the sample was tested. As shown in Figures 3-6 , the breakdown field strength of the obtained sample was 50kV / cm, the room temperature electrocaloric temperature change was 0.32K, the working temperature window was 20℃, the energy storage density was 0.14J / cm 3 , and the pyroelectric coefficient reached 35×10 -4 Cm -2 ℃- 1 . After 1000 cycles of electrocaloric test, the attenuation was less than 2%.

[0072] Example Four

[0073] The embodiment provides a lead-free relaxor ferroelectric solid solution, which has a chemical composition of 0.63BaTi 0.8 Zr 0.2 O3-0.27Ba 0.65 Sr 0.35 TiO3-0.1BaTiO3-0.1%MgO(x=0.3,y=0.1)。

[0074] Step 1: according to BaTi 0.8 Zr 0.2 O3 stoichiometric ratio, 0.05 mol of initial powder BaCO3 (9.867 g), ZrO2 (1.232 g) and TiO2 (3.195 g) are weighed; according to Ba 0.65 Sr 0.35 TiO3 stoichiometric ratio, 0.05 mol of initial powder BaCO3 (6.413 g), SrCO3 (2.584 g) and TiO2 (3.993 g) are weighed; finally, according to BaTiO3 stoichiometric ratio, 0.05 mol of initial powder BaCO3 (9.867 g) and TiO2 (3.993 g) are weighed. The three powders are respectively subjected to wet ball milling, and the mass ratio of agate ball, ball milling solvent and ball milling raw material is 5:4:1, the ball milling solvent is ethanol, and the ball milling time is 4 hours.

[0075] Step 2: after the slurry obtained by ball milling is dried at 75 DEG C, ceramic powder is obtained by pre-sintering at 1150 DEG C for 4 hours.

[0076] Step 3: according to 0.63BaTi 0.8 Zr 0.2 O3-0.27Ba 0.65 Sr 0.35 TiO3-0.1BaTiO3 stoichiometric ratio, 0.05 mol of required BaTi 0.8 Zr 0.2 O3 (7.616 g), Ba 0.65 Sr 0.35 TiO3 (2.913 g) and BaTiO3 (1.165 g) raw materials are configured. According to the proportioning ratio, MgO nano-powder is added in a mass ratio of 0.1%, and ceramic powder is obtained after drying and sieving by wet ball milling.

[0077] Step 4: 8% polyvinyl alcohol solution is added to the powder in step 3, and the amount of addition is 10% of the mass of the ceramic powder.

[0078] Step 5: the step 4 is dry-pressed by a mold, the molding pressure is 2 MPa, and the molding time is 30 seconds.

[0079] Step 6: The green sheet obtained in Step 5 was sintered at a rate of 3°C / min to 550°C for 30 min, then to 1300°C for 4 h, and cooled in the furnace. A 0.63BaTi 0.8 Zr 0.2 O3-0.27Ba 0.65 Sr 0.35 TiO3-0.1BaTiO3-0.1% MgO multifunctional relaxor ferroelectric solid solution.

[0080] Step 7: The XRD of the obtained sample is shown in Figure 1 , and the SEM is shown in Figure 2 . The ceramic sheet of Step 5 was polished to a thickness of less than 0.2 mm, and silver paste was screen-printed on the upper and lower surfaces of the ceramic. The silver electrode was obtained by sintering at 550°C for 30 min and cooling in the furnace. The sample was polarized at room temperature for 30 min using an electric field of 40 kV / cm, and the pyroelectric coefficient of the sample was tested. As shown in Figures 3-6 , the breakdown field strength of the obtained sample was 60 kV / cm, the room temperature electrocaloric temperature change was 0.58 K, the operating temperature window was 45°C, the energy storage density was 0.32 J / cm 3 , and the pyroelectric coefficient reached 182 x 10 -4 Cm -2 - 1 After 1000 cycles of electrocaloric testing, the attenuation was 30%.

[0081] Example Five

[0082] This example provides a lead-free relaxor ferroelectric solid solution with a chemical composition of 0.63BaTi 0.8 Zr 0.2 O3-0.27Ba 0.65 Sr 0.35 TiO3-0.1BaTiO3-0.5% MgO (x = 0.3, y = 0.5).

[0083] Step 1: 0.05 mol of initial powders BaCO3(9.867 g), ZrO2(1.232 g), and TiO2(3.195 g) were weighed according to the stoichiometric ratio of BaTi 0.8 Zr 0.2 O3; 0.05 mol of Ba 0.65 Sr 0.35The initial powders of BaCO3 (6.413 g), SrCO3 (2.584 g), and TiO2 (3.993 g) were weighed out according to the stoichiometric ratio of TiO3. Finally, the initial powders of BaCO3 (9.867 g) and TiO2 (3.993 g) were weighed out according to the BaTiO3 stoichiometric ratio. The three powders were then subjected to wet ball milling, with the mass ratio of agate balls, milling solvent, and milling raw materials being 5:4:1. Ethanol was used as the milling solvent, and the milling time was 4 hours.

[0084] Step 2: After drying the slurry obtained from ball milling at 75°C, pre-fire it at 1150°C for 4 hours to obtain ceramic powder.

[0085] Step 3: According to 0.63BaTi 0.8 Zr 0.2 O3-0.27Ba 0.65 Sr 0.35 Weigh out 0.05 mol of the required BaTiO3 according to the stoichiometric ratio of TiO3-0.1BaTiO3. 0.8 Zr 0.2 O3 (7.616g), Ba 0.65 Sr 0.35 TiO3 (2.913g) and BaTiO3 (1.165g) raw materials were prepared. MgO nanoparticles were added at a mass ratio of 0.5% according to the material ratio, and the mixture was wet-milled, dried, and sieved to obtain ceramic powder.

[0086] Step 4: Add 8% polyvinyl alcohol solution to the powder from Step 3, the amount added being 10% of the mass of the ceramic powder.

[0087] Step 5: The material from step 4 is dry-pressed using a mold at a pressure of 2 MPa for 30 seconds.

[0088] Step 6: Sinter the green sheet obtained in Step 5 by heating to 550℃ at a rate of 3℃ / min and holding for 30 minutes, then heating to 1300℃ and holding for 4 hours, followed by cooling in the furnace. This yields 0.63BaTi. 0.8 Zr 0.2 O3-0.27Ba 0.65 Sr 0.35 TiO3-0.1BaTiO3-0.5%MgO Multifunctional Relaxor Ferroelectric Solid Solution.

[0089] Step 7: The XRD pattern of the obtained sample is as follows Figure 1 As shown, SEM Figure 2As shown. The ceramic sheet from step 6 was polished to a thickness of 0.2 mm, and medium-temperature silver paste was screen-printed on both the upper and lower surfaces of the ceramic. It was then held at 550℃ for 30 minutes, cooled in the furnace, and fired to obtain a silver electrode. The sample was polarized at room temperature using an electric field of 40 kV / cm for 30 minutes, and the pyroelectric coefficient of the sample was measured. Figures 3-6 As shown, the breakdown field strength of the obtained sample is 90 kV / cm, the room temperature electrocaloric temperature change is 0.15 K, the operating temperature window is 30 °C, and the energy storage density is 0.8 J / cm³. 3 The pyroelectric coefficient reaches 4.5×10 -4 Cm -2 ℃- 1 After 1000 cycles of testing, the electricity consumption decreased by 2%.

[0090] Comparative Example 1

[0091] This comparative example provides a lead-free relaxor ferroelectric solid solution with a chemical composition of 0.63BaTi. 0.8 Zr 0.2 O3-0.27Ba 0.65 Sr 0.35 TiO3-0.3%MgO.

[0092] Step 1: Press BaTi 0.8 Zr 0.2 Weigh out 0.05 mol of initial powders BaCO3 (9.867 g), ZrO2 (1.232 g), and TiO2 (3.195 g) according to the stoichiometric ratio; ... 0.65 Sr 0.35 The initial powders of TiO3, namely BaCO3 (6.413 g), SrCO3 (2.584 g), and TiO2 (3.993 g), were weighed out in stoichiometric proportions of 0.05 mol each. The powders were then subjected to wet ball milling with a mass ratio of agate balls, milling solvent, and milling raw material of 5:4:1. Ethanol was used as the milling solvent, and the milling time was 4 hours.

[0093] Step 2: After drying the slurry obtained from ball milling at 75°C, pre-fire it at 1150°C for 4 hours to obtain ceramic powder.

[0094] Step 3: According to 0.63BaTi 0.8 Zr 0.2 O3-0.27Ba 0.65 Sr 0.35 Weigh out 0.05 mol of the required BaTiO3 stoichiometric amount. 0.8 Zr 0.2 O3(7.616g) and Ba 0.65 Sr 0.35The raw materials of TiO3(2.913g) were prepared. The ceramic powder was obtained by adding MgO nano-powder with a mass ratio of 0.3% according to the proportion of the ingredients, using wet ball milling, drying, and sieving.

[0095] Step 4: 8% polyvinyl alcohol solution was added to the powder of step 3, and the amount of addition was 10% of the mass of the ceramic powder.

[0096] Step 5: The step 4 was dry-pressed by a mold, the molding pressure was 2Mpa, and the molding time was 30 seconds.

[0097] Step 6: The green sheet obtained in step 5 was sintered, the temperature was raised to 550℃ at a rate of 3℃ / min, and the temperature was kept for 30 minutes. Then the temperature was raised to 1300℃ and kept for 4 hours, and the furnace was cooled down. Thus, 0.63BaTi 0.8 Zr 0.2 O3-0.27Ba 0.65 Sr 0.35 TiO3-0.3% MgO multifunctional relaxor ferroelectric solid solution was obtained.

[0098] Step 7: The ceramic sheet of step 6 was polished to a thickness of less than 0.2mm, and silver paste was screen-printed on the upper and lower surfaces of the ceramic. Then the silver electrode was obtained by sintering at 550℃ for 30min and cooling in the furnace. The sample was polarized at room temperature for 30min under an electric field of 50kV / cm, and the pyroelectric coefficient of the sample was tested. The breakdown field strength of the obtained sample was 70kV / cm, the Curie temperature of the obtained sample was moved to -10℃, the room temperature was paraelectric phase, the room temperature electric card temperature change was reduced to less than 0.1K, and the energy storage density was 0.2J / cm 3 No pyroelectric peak was detected in the test temperature range.

[0099] Comparative Example Two

[0100] The present embodiment provides a lead-free relaxor ferroelectric solid solution, which has a chemical composition of 0.27Ba 0.65 Sr 0.35 TiO3-0.1BaTiO3-0.3% MgO.

[0101] Step 1: 0.05mol of initial powder BaCO3(6.413g), SrCO3(2.584g), and TiO2(3.993g) were weighed according to the stoichiometric ratio of Ba 0.65 Sr 0.35 TiO3, and finally 0.05mol of initial powder BaCO3(9.867g) and TiO2(3.993g) were weighed according to the stoichiometric ratio of BaTiO3. The two kinds of powders were wet ball milled respectively, the mass ratio of agate ball, ball milling solvent, and ball milling raw material was 5:4:1, the ball milling solvent was ethanol, and the ball milling time was 4 hours.

[0102] Step 2: After drying the slurry obtained from ball milling at 75°C, pre-fire it at 1150°C for 4 hours to obtain ceramic powder.

[0103] Step 3: According to 0.27Ba 0.65 Sr 0.35 To prepare a TiO3-0.1BaTiO3 stoichiometric formula, weigh out 0.05 mol of the required Ba. 0.65 Sr 0.35 TiO3 (2.913g) and BaTiO3 (1.165g) raw materials were prepared. MgO nanoparticles were added at a mass ratio of 0.3% according to the ingredient ratio, and the mixture was wet-milled, dried, and sieved to obtain ceramic powder.

[0104] Step 4: Add 8% polyvinyl alcohol solution to the powder from Step 3, the amount added being 10% of the mass of the ceramic powder.

[0105] Step 5: The material from step 4 is dry-pressed using a mold at a pressure of 2 MPa for 30 seconds.

[0106] Step 6: Sinter the green sheet obtained in Step 5 by heating to 550℃ at a rate of 3℃ / min and holding for 30 minutes, then heating to 1300℃ and holding for 4 hours, followed by cooling in the furnace. This yields 0.27Ba. 0.65 Sr 0.35 TiO3-0.1BaTiO3-0.3%MgO Multifunctional Relaxor Ferroelectric Solid Solution.

[0107] Step 7: The XRD pattern of the obtained sample is as follows Figure 1 As shown, SEM Figure 2 As shown. The ceramic sheet from step 5 was polished to a thickness of less than 0.2 mm. Medium-temperature silver paste was screen-printed on both the upper and lower surfaces of the ceramic sheet. It was then held at 550℃ for 30 min, cooled in the furnace, and fired to obtain a silver electrode. The sample was polarized at room temperature using an electric field of 50 kV / cm for 30 min, and the pyroelectric coefficient of the sample was tested. The resulting sample had a breakdown field strength of 80 kV / cm, a room temperature electrocaloric temperature change of 0.2 K, an operating temperature window of 20℃, and a storage density of 0.5 J / cm³. 3 The pyroelectric coefficient reaches 15×10 -4 Cm -2 ℃ -1 After 1000 cycles of testing, the battery capacity decreased by more than 40%.

[0108] Comparative Example 3

[0109] This embodiment provides a lead-free relaxor ferroelectric solid solution with a chemical composition of 0.63BaTi. 0.8 Zr 0.2O3-0.1 BaTiO3-0.3% MgO.

[0110] Step 1: 0.63 BaTi 0.8 Zr 0.2 0.05 mol of initial powder BaCO3(9.867 g), ZrO2(1.232 g) and TiO2(3.195 g) were weighed according to the stoichiometric ratio of BaTiO3, respectively; 0.05 mol of initial powder BaCO3(9.867 g) and TiO2(3.993 g) were weighed according to the stoichiometric ratio of BaTiO3, respectively. The above two powders were subjected to wet ball milling, respectively, with a mass ratio of agate ball, ball milling solvent and ball milling raw material of 5:4:1, the ball milling solvent was ethanol, and the ball milling time was 4 hours.

[0111] Step 2: After the slurry obtained by ball milling was dried at 75°C, ceramic powder was obtained by pre-sintering at 1150°C for 4 hours.

[0112] Step 3: 0.63 BaTi 0.8 Zr 0.2 0.05 mol of BaTi 0.8 Zr 0.2 O3(7.616 g) and BaTiO3(1.165 g) raw materials were weighed according to the stoichiometric ratio of 0.63 BaTi

[0113] Step 4: 8% polyvinyl alcohol solution was added to the powder of step 3, and the amount of addition was 10% of the mass of the ceramic powder.

[0114] Step 5: The step 4 was dry pressed by a mold, the molding pressure was 2 MPa, and the molding time was 30 seconds.

[0115] Step 6: The green compact sheet obtained in step 5 was sintered, the temperature was raised to 550°C at a rate of 3°C / min and kept for 30 minutes, then the temperature was raised to 1300°C and kept for 4 hours, and the furnace was cooled down. Thus, 0.63 BaTi 0.8 Zr 0.2 O3-0.1 BaTiO3-0.3% MgO multifunctional relaxor ferroelectric solid solution was obtained.

[0116] Step 7: The XRD of the obtained sample is shown in Figure 1 , and the SEM is shown in Figure 2The ceramic sheet of step 5 was polished to a thickness of less than 0.2 mm, and a medium-temperature silver paste was screen-printed on the upper and lower surfaces of the ceramic. The sample was then baked at 550°C for 30 min and cooled in the furnace to obtain a silver electrode. The pyroelectric coefficient of the sample was measured at room temperature under an electric field of 50 kV / cm for 30 min. The breakdown field strength of the sample was 110 kV / cm, the room-temperature electrocaloric temperature change was 0.5 K, the working temperature window was 25°C, and the energy storage density was 0.3 J / cm 3 , and the pyroelectric coefficient reached 12 x 10 -4 Cm -2 ℃ -1 . After 1000 cycles of electrocaloric testing, the sample was attenuated by more than 30%.

[0117] Comparative Example Four

[0118] This comparative example provides a lead-free relaxor ferroelectric solid solution having a chemical composition of 0.63BaTi 0.8 Zr 0.2 O3-0.27Ba 0.65 Sr 0.35 TiO3.

[0119] Step 1: 0.05 mol of initial powders BaCO3(9.867 g), ZrO2(1.232 g), and TiO2(3.195 g) were weighed according to the stoichiometric ratio of BaTi 0.8 Zr 0.2 O3, and 0.05 mol of initial powders BaCO3(6.413 g), SrCO3(2.584 g), and TiO2(3.993 g) were weighed according to the stoichiometric ratio of Ba 0.65 Sr 0.35 TiO3. The two powders were wet ball milled, respectively, with a mass ratio of agate ball, ball milling solvent, and ball milling raw material of 5:4:1, the ball milling solvent was ethanol, and the ball milling time was 4 hours.

[0120] Step 2: The slurry obtained by ball milling was dried at 75°C, and ceramic powder was obtained by pre-sintering at 1150°C for 4 hours.

[0121] Step 3: 0.05 mol of BaTi 0.8 Zr 0.2 O3-0.27Ba 0.65 Sr 0.35 TiO3 was weighed according to the stoichiometric ratio, and 0.05 mol of BaTi 0.8 Zr 0.2 O3(8.465 g) and Ba 0.65 Sr 0.35 TiO3(3.237 g) raw materials were configured. The ceramic powder was obtained by drying and sieving after wet ball milling.

[0122] Step 4: Add 8% polyvinyl alcohol solution to the powder from Step 3, the amount added being 10% of the mass of the ceramic powder.

[0123] Step 5: The material from step 4 is dry-pressed using a mold at a pressure of 2 MPa for 30 seconds.

[0124] Step 6: Sinter the green sheet obtained in Step 5 by heating to 550℃ at a rate of 3℃ / min and holding for 30 minutes, then heating to 1300℃ and holding for 4 hours, followed by cooling in the furnace. This yields 0.63BaTi. 0.8 Zr 0.2 O3-0.27Ba 0.65 Sr 0.35 TiO3 is a multifunctional relaxor ferroelectric solid solution.

[0125] Step 7: The ceramic sheet from Step 6 is polished to a thickness of less than 0.2 mm. Medium-temperature silver paste is screen-printed onto the upper and lower surfaces of the ceramic sheet. It is then held at 550℃ for 30 minutes, cooled in the furnace, and fired to obtain a silver electrode. The sample is polarized at room temperature using an electric field of 30 kV / cm for 30 minutes, and the pyroelectric coefficient is measured. The resulting sample has a breakdown field strength of 60 kV / cm, a room temperature electrocaloric temperature change of 0.4 K, an operating temperature window of 20℃, and a storage density of 0.28 J / cm³. 3 The pyroelectric coefficient reaches 82×10 -4 Cm -2 ℃ -1 After 10 cycles of electrocaloric testing, significant Joule heating was observed, confirming the presence of a high concentration of electrochemical defects within the solid solution.

[0126] Comparative Example 5

[0127] This comparative example provides a lead-free relaxor ferroelectric solid solution with a chemical composition of 0.63BaTi. 0.8 Zr 0.2 O3-0.27Ba 0.65 Sr 0.35 TiO3-0.1BaTiO3.

[0128] Step 1: Press BaTi 0.8 Zr 0.2 Weigh out 0.05 mol of initial powders BaCO3 (9.867 g), ZrO2 (1.232 g), and TiO2 (3.195 g) according to the stoichiometric ratio; ... 0.65 Sr 0.35The initial powders of BaCO3(6.413 g), SrCO3(2.584 g) and TiO2(3.993 g) are weighed according to the stoichiometric ratio of BaTiO3, 0.05 mol; finally, the initial powders of BaCO3(9.867 g) and TiO2(3.993 g) are weighed according to the stoichiometric ratio of BaTiO3, 0.05 mol. The three powders are wet ball-milled, with a mass ratio of agate ball, ball-milling solvent and ball-milling raw material of 5:4:1, the ball-milling solvent being ethanol, and the ball-milling time being 4 hours.

[0129] Step 2: The slurry obtained by ball-milling is dried at 75°C, and ceramic powder is obtained by pre-sintering at 1150°C for 4 hours.

[0130] Step 3: The initial powders of BaCO3(6.413 g), SrCO3(2.584 g) and TiO2(3.993 g) are weighed according to the stoichiometric ratio of BaTiO3, 0.05 mol; finally, the initial powders of BaCO3(9.867 g) and TiO2(3.993 g) are weighed according to the stoichiometric ratio of BaTiO3, 0.05 mol. The three powders are wet ball-milled, with a mass ratio of agate ball, ball-milling solvent and ball-milling raw material of 5:4:1, the ball-milling solvent being ethanol, and the ball-milling time being 4 hours. 0.8 Zr 0.2 O3-0.27Ba 0.65 Sr 0.35 TiO3-0.1BaTiO3 stoichiometric ratio of 0.05 mol. Wet ball-milling is performed, and the mixed powder is obtained after drying and sieving. 0.8 Zr 0.2 O3(7.616 g), Ba 0.65 Sr 0.35 TiO3(2.913 g) and BaTiO3(1.165 g) raw materials are configured. Wet ball-milling is performed, and the mixed powder is obtained after drying and sieving.

[0131] Step 4: 8% polyvinyl alcohol solution is added to the powder of step 3, and the amount of addition is 10% of the mass of the ceramic powder.

[0132] Step 5: The green compact of step 4 is dry-pressed by a mold, with a molding pressure of 2 MPa and a molding time of 30 seconds.

[0133] Step 6: The green compact of step 5 is sintered, with a temperature rising rate of 3°C / min to 550°C for 30 minutes, then a temperature rising rate of 3°C / min to 1300°C for 4 hours, and a furnace cooling, to obtain 0.63BaTi 0.8 Zr 0.2 O3-0.27Ba 0.65 Sr 0.35 TiO3-0.1BaTiO3 multifunctional lead-free relaxor ferroelectric solid solution.

[0134] Step 7: The ceramic sheet of step 6 is polished to 0.2 mm thickness, and a middle-temperature silver paste is screen-printed on the upper and lower surfaces of the ceramic, and then fired at 550°C for 30 min and cooled in the furnace to obtain a silver electrode. The sample is polarized at room temperature for 30 min using an electric field of 30 kV / cm, and the pyroelectric coefficient of the sample is tested. The breakdown field strength of the obtained sample is 40 kV / cm, the room-temperature electrocaloric temperature change is 0.2 K, the working temperature window is 20°C, and the energy storage density is 0.3 J / cm 3 , and the pyroelectric coefficient reaches 63 x 10 -4 Cm -2 - 1 After 2 cycles of electrocaloric testing, the lead-free relaxor ferroelectric solid solution is broken down.

[0135] Comparative Example Six

[0136] This comparative example provides a preparation method of a lead-free relaxor ferroelectric solid solution [0.63BaTi 0.8 Zr 0.2 O3-0.27Ba 0.65 Sr 0.35 TiO3-0.1BaTiO3-0.3% MgO].

[0137] Step 1: 0.05 mol of initial powders BaCO3 (8.934 g), SrCO3 (0.698 g), ZrO2 (0.776 g), TiO2 (3.481 g) and MgO (0.035 g) are weighed according to the stoichiometric ratio of 0.63BaTi 0.8 Zr 0.2 O3-0.27Ba 0.65 Sr 0.35 TiO3-0.1BaTiO3-0.3% MgO.

[0138] Step 2: The slurry obtained by ball milling is dried at 75°C, and ceramic powder is obtained by pre-sintering at 1150°C for 4 hours.

[0139] Step 3: 8% of a polyvinyl alcohol solution is added to the powder of step 2, and the amount of addition is 10% of the mass of the ceramic powder.

[0140] Step 4: The step 3 is dry-pressed by a mold, and the molding pressure is 2 MPa and the molding time is 30 s.

[0141] Step 5: The green sheet obtained in step 4 is sintered, and the temperature is increased to 550°C at a rate of 5°C / min, and then the temperature is increased to 1300°C and kept for 4 hours, and then the temperature is decreased in the furnace to obtain 0.63BaTi 0.8Zr 0.2 O3-0.27Ba 0.65 Sr 0.35 TiO3-0.1BaTiO3-0.3%MgO multi-function lead-free relaxor ferroelectric solid solution.

[0142] Step 6: The ceramic sheet of step 5 is polished to a thickness of less than 0.2 mm, and a medium-temperature silver paste is screen-printed on the upper and lower surfaces of the ceramic. The sample is then baked at 550°C for 30 min and cooled in the furnace to obtain silver electrodes. The sample is polarized at room temperature using an electric field of 20 kV / cm for 30 min, and the pyroelectric coefficient of the sample is tested. The breakdown field strength of the obtained sample is 70 kV / cm, the room-temperature electrocaloric temperature change is 0.5 K, the working temperature window is 35°C, and the energy storage density is 0.53 J / cm 3 , and the pyroelectric coefficient reaches 55×10 -4 Cm -2 °C. 1 After 10 cycles of electrocaloric testing, the electrocaloric temperature change is attenuated by 1%.

[0143] The above description is merely preferred embodiments of the present application but not to confine the present application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall fall within the protection scope of the present application.

Claims

1. A lead-free relaxor ferroelectric solid solution, characterized in that: The chemical composition of the lead-free relaxor ferroelectric solid solution is 0.9(1-x)BaTi 0.8 Zr 0.2 O3-xBa 0.65 Sr 0.35 TiO3)-0.1BaTiO3-y%MgO, where x represents the molar coefficient and y represents the mass percentage. The x is 0.3 and the y is 0.3; The method for preparing the lead-free relaxor ferroelectric solid solution includes the following steps: S1. Mix BaCO3, TiO2, and ZrO2 according to the BaTi... 0.8 Zr 0.2 The first ceramic powder was obtained by preparing the stoichiometric ratio of O3. BaCO3, SrCO3, and TiO2 were then mixed according to the Ba... 0.65 Sr 0.35 The second ceramic powder is obtained by stoichiometrically preparing TiO3, and the third ceramic powder is obtained by stoichiometrically preparing BaCO3 and TiO2. S2. The first ceramic powder, the second ceramic powder and the third ceramic powder are ball-milled once, mixed evenly and then pre-fired. S3. The pre-fired first ceramic powder, second ceramic powder and third ceramic powder are prepared according to the stoichiometric ratio, and MgO nanoparticles are added at the same time. The mixture is then ball-milled twice, and then dried, sieved, granulated and dry-pressed to form a ceramic green body. S4. The ceramic green body is sintered, and after sintering, it is cooled down in the furnace to obtain the relaxor ferroelectric solid solution. In step S3, the incorporation ratio of MgO nanopowder is equal to 0.3% of the total mass of the first ceramic powder, the second ceramic powder, and the third ceramic powder. The sintering of the ceramic green body in step S4 specifically includes the following steps: S401. Heat the ceramic green body to 550~600℃ and hold for 30~45 minutes; S402. Continue to heat the ceramic green body to 1200-1500℃ and hold it for 3-8 hours.

2. The lead-free relaxor ferroelectric solid solution as described in claim 1, characterized in that: The particle size of the MgO nanopowder is 80~120nm.

3. The lead-free relaxor ferroelectric solid solution as described in claim 1, characterized in that: In step S2, the agate balls, milling solvent, and powder are milled once at a mass ratio of (1.4~2.2):1:(0.45~0.58). The solvent for the first milling is ethanol, and the milling time is 2~6 hours.

4. The lead-free relaxor ferroelectric solid solution as described in claim 1, characterized in that: In step S2, the pre-firing heating rate is 2~10℃ / min, the pre-firing temperature is 100~1300℃, and the pre-firing time is 2~6h.

5. The lead-free relaxor ferroelectric solid solution as described in claim 1, characterized in that: The drying conditions in step S3 are: drying temperature of 60~75℃ and drying time of 1~6h.

6. The lead-free relaxor ferroelectric solid solution as described in claim 1, characterized in that: In step S3, 5% to 20% polyvinyl alcohol solution is added during granulation, and the amount of polyvinyl alcohol solution added is 10% to 20% of the powder mass.

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