Bismuth sodium titanate-based lead-free textured ceramic with high piezoelectricity and ultra-low hysteresis and preparation thereof

Abstract

The application relates to the technical field of functional ceramics, and relates to a sodium bismuth titanate-based lead-free textured ceramic with high electrocaloric properties and ultralow hysteresis and a preparation method of the sodium bismuth titanate-based lead-free textured ceramic. 0.5 Na 0.5 TiO3-0.24SrTiO3-MnO-CuO-SrTiO3-NaNbO3, compared with the prior art, the sodium bismuth titanate-based lead-free piezoelectric textured ceramic prepared by the application mixes strontium titanate and sodium niobate templates, combines the advantages of the two, obtains the sodium bismuth titanate-based lead-free piezoelectric textured ceramic with a higher texture degree, and meanwhile, the sodium niobate template also plays a doping role, effectively improves the relaxation degree of the system, and greatly reduces the hysteresis.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of functional ceramics, in particular to a sodium bismuth titanate-based lead-free textured ceramic with high electrostrictive performance and ultra-low hysteresis and a preparation method thereof. BACKGROUND

[0002] Piezoelectric materials are widely used in transducers, sensors, medical imaging, brakes, etc. Since lead-based materials are harmful to the environment and human body, lead-free piezoelectric materials have gradually become a research hotspot.

[0003] However, the piezoelectric ceramics that dominate the market at present are still lead-based systems such as lead titanate and lead zirconate titanate, mainly because of their excellent electrical properties. Among lead-free systems, sodium niobate exhibits piezoelectric properties comparable to lead-based materials, and bismuth ferrite performs well at high temperatures, especially in the field of electrostrictive strain. Sodium bismuth titanate is the most promising lead-free system to replace lead-based materials, mainly due to its excellent electrostrictive strain performance, lower sintering temperature and wider sintering temperature range, which are unmatched by other lead-free systems.

[0004] Although sodium bismuth titanate has excellent electrostrictive strain performance, it still has some problems in practical applications, such as strain performance not reaching the level of commercial lead-based materials and having a large strain hysteresis. Current research mainly focuses on improving the strain level, such as the quasi-critical point constructed by Malik RA et al. through niobium (Nb) ion doping, which makes the strain level of sodium bismuth titanate-based materials reach 0.45%. Similar reports on the construction of quasi-critical points are numerous, and the strain performance can reach a high level of 0.4-0.5%. In addition, texture is another effective method to improve strain performance. Fancher CM et al. prepared <001> oriented textured ceramics through sodium niobate templates and obtained a large strain response of 0.47%. However, both of the above methods do not help to reduce the strain hysteresis, and the prepared ceramics basically have a large strain hysteresis of >50%. The current method that can effectively reduce the hysteresis is ion doping, which increases the relaxation degree of the system, but it also sacrifices the strain performance. Therefore, maintaining a large strain while having a low hysteresis is a dilemma. SUMMARY

[0005] The purpose of the present application is to overcome the defects of the prior art and provide a sodium bismuth titanate-based lead-free textured ceramic with high electrostrictive performance and ultra-low hysteresis and a preparation method thereof.

[0006] The purpose of the present application can be achieved by the following technical solutions:

[0007] A sodium bismuth titanate-based lead-free textured ceramic with high electrostrictive performance and ultra-low hysteresis, characterized by a chemical composition of 0.76Bi 0.5Na 0.5 TiO3-0.24SrTiO3-MnO-CuO-SrTiO3-NaNbO3,

[0008] said 0.76Bi 0.5 Na 0.5 TiO3-0.24SrTiO3, Bi 0.5 Na 0.5 TiO3-0.24SrTiO3, the molar concentration of Bi

[0009] said 0.76Bi 0.5 Na 0.5 TiO3-0.24SrTiO3-MnO-CuO, the mass concentration of MnO is 0.25wt%, the mass concentration of CuO is 0.25wt%,

[0010] said 0.76Bi 0.5 Na 0.5 TiO3-0.24SrTiO3-MnO-CuO-SrTiO3-NaNbO3, the mass concentration of SrTiO3 is 1.5-2.5wt%, the mass concentration of NaNbO3 is 1.5-2.5wt%.

[0011] A preparation method of a sodium bismuth titanate-based lead-free textured ceramic with high electro-optic effect and ultra-low hysteresis, comprising the following steps:

[0012] S1: according to the chemical composition of 0.76Bi 0.5 Na 0.5 TiO3-0.24SrTiO3-MnO-CuO, a sodium source, a bismuth source, a strontium source and a titanium source are mixed, and first ball milling, calcination are carried out in sequence, after calcination, a manganese source and a copper source are added, and second ball milling, discharging and drying are carried out to obtain a flow casting powder base material;

[0013] S2: according to the chemical composition of NaNbO3, a bismuth source, a potassium source, a niobium source and a first molten salt are taken to prepare a precursor by a first molten salt reaction, the prepared precursor, potassium carbonate and the first molten salt are synthesized and filtered to obtain a sodium niobate template;

[0014] S3: according to the chemical composition of SrTiO3, a bismuth source and a titanium source are taken to carry out ball milling and heat preservation with a second molten salt, and an intermediate is obtained after filtration, strontium carbonate and a third molten salt are ball milled and then added to the intermediate, and strontium titanate template is obtained after ball milling, heat preservation and filtration;

[0015] S4: the flow casting powder base material, the sodium niobate template and the strontium titanate template are mixed to obtain a raw material powder, a solvent and an auxiliary agent are added, and then roll milling, flow casting, laminating and pressing, degassing and sintering are carried out in sequence to obtain the sodium bismuth titanate-based lead-free textured ceramic.

[0016] Furthermore, in step S1, the sodium source includes sodium carbonate, the bismuth source includes bismuth trioxide, the strontium source includes strontium carbonate, the titanium source includes titanium oxide, the manganese source includes manganese oxide, and the copper source includes copper oxide.

[0017] Furthermore, in step S1, the mass ratio of the sodium source, bismuth source, strontium source and titanium source is: (2-2.3): (8.5-9): (3.5-3.6): (8-8.5), the calcination temperature is 700-900°C, and the calcination time is 2-4h.

[0018] Furthermore, in step S2, the bismuth source includes bismuth trioxide, the potassium source includes potassium carbonate, the niobium source includes niobium pentoxide, and the first molten salt is sodium chloride.

[0019] Furthermore, in step S2, when preparing the precursor, the mass ratio of the bismuth source, potassium source, niobium source, and first molten salt is 10: (3-3.5): (8.5-9): (24-24.2), the reaction temperature is 1000-1100°C, and the reaction time is 2-3h; when further preparing the sodium niobate template, the mass ratio of the precursor, potassium carbonate, and the first molten salt is 8: (1-1.5): (10-10.5), and the synthesis temperature is 970-1000°C.

[0020] Furthermore, in step S3, the bismuth source includes bismuth trioxide, the titanium source includes titanium oxide, the second molten salt is selected from sodium chloride and potassium chloride, wherein the molar ratio of sodium chloride to potassium chloride is 1:1, and the third molten salt is selected from potassium chloride.

[0021] Furthermore, in step S3, when preparing the intermediate, the mass ratio of the bismuth source, the titanium source, and the second molten salt is (19-20): (5-5.5): 25, the insulation temperature is 1100°C, and the insulation time is 1.5h; when further preparing the strontium titanate template, the mass ratio of the strontium carbonate, the third molten salt ball mill, and the intermediate is (6.5-7): (18-18.5): (11.5-12).

[0022] Furthermore, in step S4, the solvent includes one of butanone and ethanol or a mixture of the two, and the auxiliary agent includes a dispersant, a plasticizer and a binder.

[0023] The dispersant includes triolein, the plasticizer includes one of polyethylene glycol and dibutyl phthalate or a mixture of the two, and the binder includes polyvinyl butyral.

[0024] Further, in step S4, the raw material powder, solvent, dispersant, plasticizer, and binder are added in a mass ratio of 10:13.5:(0.3-0.4):0.65:0.7.

[0025] Compared with the prior art, the present application has the following advantages and beneficial effects:

[0026] (1) The sodium bismuth titanate-based lead-free piezoelectric textured ceramic prepared by the present application has excellent electrostrictive performance and ultra-low strain hysteresis.

[0027] (2) The introduction of the double template and the sintering aid greatly reduces the sintering temperature, and an ultra-high texture degree can be obtained at this low sintering temperature.

[0028] (3) The preparation method of the present application is simple, economical and practical, and belongs to a lead-free and environmentally friendly system, which is of great significance to the development of the brake field. BRIEF DESCRIPTION OF DRAWINGS

[0029] Figure 1 X-ray diffraction (XRD) pattern of the sodium bismuth titanate-based lead-free textured ceramic with high electrostrictive performance and ultra-low hysteresis in Example 1 and Comparative Examples 1-2 of the present application;

[0030] Figure 2 Scanning electron microscope (SEM) image of the sodium bismuth titanate-based lead-free textured ceramic with high electrostrictive performance and ultra-low hysteresis in Example 1 of the present application;

[0031] Figure 3 Dielectric temperature spectrum of the sodium bismuth titanate-based lead-free textured ceramic with high electrostrictive performance and ultra-low hysteresis in Example 1 and Comparative Examples 1-2 of the present application;

[0032] Figure 4 Electrostrictive strain diagram of the sodium bismuth titanate-based lead-free textured ceramic with high electrostrictive performance and ultra-low hysteresis in Example 1 and Comparative Examples 1-2 of the present application;

[0033] Figure 5 Electrostrictive strain and hysteresis statistical diagram of the sodium bismuth titanate-based lead-free textured ceramic with high electrostrictive performance and ultra-low hysteresis in Example 1 and Comparative Examples 1-2 of the present application. DETAILED DESCRIPTION

[0034] The present application will be described in detail below in conjunction with the drawings and specific embodiments.

[0035] A sodium bismuth titanate-based lead-free textured ceramic with high electrostrictive performance and ultra-low hysteresis, the chemical composition of the ceramic being 0.76Bi 0.5 Na 0.5TiO3-0.24SrTiO3-0.25wt%MnO-0.25wt%CuO-x, wherein x = 2wt%SrTiO3-2wt%NaNbO3, the sodium bismuth titanate-based piezoelectric ceramic has an electric strain of 0.5% (100kV / cm electric field applied) and a hysteresis of 15%, and the sodium bismuth titanate-based lead-free piezoelectric ceramic has a grain orientation of <001> C =95%, has high electric strain and super low hysteresis.

[0036] A method for preparing a sodium bismuth titanate-based lead-free piezoelectric ceramic with high electric strain and super low hysteresis, comprising the following steps:

[0037] S1: according to the chemical composition, the sodium source, the bismuth source, the strontium source and the titanium source (purity > 99%) are weighed according to the chemical formula, mixed, and then subjected to primary ball milling (medium: ethanol, 170ml) for 20-24h, calcination (800℃ for 4h), after calcination, manganese source and copper source are added, and secondary ball milling (medium: ethanol) is carried out for 20-24h, and the material is discharged and dried to obtain a flow casting powder base material;

[0038] S2: the bismuth source, the potassium source and the niobium source are taken to prepare a precursor by first molten salt reaction (melting temperature: 1000-1100℃, holding time: 2-3h), the prepared precursor, potassium carbonate and the first molten salt are synthesized (melting temperature: 970-1000℃) and filtered to obtain a sodium niobate template;

[0039] S3: the bismuth source and the titanium source are taken to carry out ball milling (medium: ethanol, ball milling for 24h) with the second molten salt, and then subjected to holding (temperature: 1100℃, holding time: 1.5h), and after filtration, an intermediate is obtained, strontium carbonate and the third molten salt are ball milled (medium: ethanol, ball milling for 20h) and then added to the intermediate, and then subjected to ball milling (medium: ethanol, ball milling for 4h) and holding (temperature: 1100℃, holding time: 3h), and after filtration, a strontium titanate template is obtained;2

[0040] S4: the flow casting powder base material, the sodium niobate template and the strontium titanate template are mixed to obtain a raw material powder, a solvent (butanone and ethanol) and an additive (glyceryl trioleate as a dispersant, polyethylene glycol and dibutyl phthalate as plasticizers, and polyvinyl butyral as a bonding agent) are added, and then subjected to roll milling (roll milling machine roll milling for 8h) to obtain a flow casting slurry,

[0041] The flow casting slurry is flow casted, and in the flow casting process, the scraper moving speed is 25-30cm / min, and after drying, a thick film with certain toughness and plasticity is obtained, and the thickness is controlled to be 14 microns;

[0042] The thick film is laminated, cut and hot pressed to obtain a ceramic green body;

[0043] The ceramic green body is degreased in a muffle furnace at a temperature of 600 DEG C for 10-15 h;

[0044] The degreased ceramic body is sintered at a temperature of 1075 DEG C for 20 h;

[0045] After natural cooling to room temperature, the ceramic sheet is ground and polished to obtain a sodium bismuth titanate-based lead-free textured ceramic with a thickness of 0.4 mm.

[0046] In some embodiments of the present application, in step S1, the sodium source is sodium carbonate, the bismuth source is bismuth trioxide, the strontium source is strontium carbonate, the titanium source is titanium oxide, the manganese source is manganese oxide, and the copper source is copper oxide;

[0047] In some embodiments of the present application, in step S1, the mass ratio of the sodium source, the bismuth source, the strontium source, and the titanium source is (2-2.3):(8.5-9):(3.5-3.6):(8-8.5);

[0048] In some embodiments of the present application, in step S2, the bismuth source is bismuth trioxide, the potassium source is potassium carbonate, the niobium source is niobium pentoxide, and the first molten salt is sodium chloride;

[0049] In some embodiments of the present application, in step S2, in the preparation of the precursor, the mass ratio of the bismuth source, the potassium source, the niobium source, and the first molten salt is 10:(3-3.5):(8.5-9):(24-24.2), and in the further preparation of the sodium niobate template, the mass ratio of the precursor, the potassium carbonate, and the first molten salt is 8:(1-1.5):(10-10.5);

[0050] In some embodiments of the present application, in step S3, the bismuth source is bismuth trioxide, the titanium source is titanium oxide, the second molten salt is sodium chloride and potassium chloride, and the molar ratio of sodium chloride to potassium chloride is 1:1, and the third molten salt is potassium chloride;

[0051] In some embodiments of the present application, in step S3, in the preparation of the intermediate, the mass ratio of the bismuth source, the titanium source, and the second molten salt is (19-20):(5-5.5):25, and in the further preparation of the strontium titanate template, the mass ratio of the strontium carbonate, the third molten salt, and the intermediate is (6.5-7):(18-18.5):(11.5-12).

[0052] In some embodiments of the present application, in step S4, the solvent is a mixture of butanone and ethanol, and the additives include a dispersant, a plasticizer, and a binder, wherein the dispersant is glyceryl trioleate, the plasticizer is a mixture of polyethylene glycol and dibutyl phthalate, and the binder is polyvinyl butyral;

[0053] In some embodiments of the present application, in step S4, the mass ratio of the raw material powder, the solvent, the dispersant, the plasticizer, and the binder is 10:13.5:(0.3-0.4):0.65:0.7.

[0054] The following examples are implemented on the basis of the above technical solutions of the present application, and detailed implementation modes and specific operation processes are given, but the protection scope of the present application is not limited to the following examples.

[0055] The following are more detailed implementation cases, which further illustrate the technical solutions of the present application and the technical effects that can be obtained.

[0056] In the following examples, if no special raw reagent or processing technology is indicated, it means that it is a conventional commercially available product or a conventional processing technology in the art.

[0057] Example 1

[0058] The present embodiment provides a sodium bismuth titanate-based lead-free textured ceramic with high electro-activity and ultra-low hysteresis and a preparation method thereof. The sodium bismuth titanate-based lead-free textured ceramic has a chemical composition of 96wt%[99.5wt%(76mol%Bi 0.5 Na 0.5 TiO3-24mol%SrTiO3)-0.25wt%MnO-0.25wt%CuO]-2wt%SrTiO3-2wt%NaNbO3,

[0059] The preparation method has the following specific steps:

[0060] (1) According to the stoichiometric ratio of 76mol%Bi 0.5 Na 0.5 TiO3-24mol%SrTiO3, take Na2CO32.0219g, Bi2O38.9605g, SrCO33.5789g, and TiO28.1496g as the raw material of the lead-free piezoelectric ceramic, add 170ml of ethanol as the medium for ball milling, and discharge and dry after 24h;

[0061] (2) The dried powder is calcined at a calcination temperature of 800°C for 4h;

[0062] (3) The calcined powder is added with MnO and CuO (wherein, in 76mol%Bi 0.5 Na 0.5 TiO3-24mol%SrTiO3-MnO-CuO, the mass concentration of MnO is 0.25wt%, and the mass concentration of CuO is 0.25wt%), and is secondarily ball milled in the medium ethanol (ethanol 170ml) for 24h, and then discharged and dried to obtain a flow casting powder base.

[0063] (4) Sodium niobate template was prepared by two-step molten salt method: In the first step, 10 g Bi2O3, 3.1942 g K2CO3, 8.7762 g Nb2O5 and 24.1674 g NaCl were reacted, melted at 1100 °C for 3 h, filtered, and the flake precursor Bi 2.5 Na 3.5 Nb5O 18 ;

[0064] In the second step, 8 g of the flake precursor, 1.3705 g of K2CO3, and 10.3076 g of NaCl were used for synthesis, melted and held at 970 ° C for 2 h, and filtered to obtain the sodium niobate flake template;

[0065] (5) The strontium titanate template was prepared by a two-step molten salt method: In the first step, 19.8870 g Bi2O3, 5.1130 g TiO2, 10.9860 g NaCl and 14.0140 g KCl were ball-milled in 200 ml of ethanol for 24 h, kept at 1100 °C for 1.5 h, and filtered to obtain a flaky intermediate Bi4Ti3O 12 ;

[0066] In the second step, 6.6433 g of SrCO3 and 18.3585 g of molten salt KCl were ball-milled for 20 h, and then 11.7152 g of the intermediate Bi4Ti3O was added. 12 The product was ball-milled for another 4 h (using 200 ml of ethanol as the medium), dried, and kept at 1100 °C for 3 h. The flaky strontium titanate template was obtained after filtration.

[0067] (6) The tape casting powder base material obtained in step (3) and steps (4) and (5), sodium niobate template, strontium titanate template, solvent, dispersant, plasticizer, and binder are mixed in proportion and rolled for 8 hours to obtain a tape casting slurry;

[0068] The mass ratio of the tape-casting powder base material, sodium niobate template, strontium titanate template, triolein, ethanol, butanone, dibutyl phthalate, polyethylene glycol and polyvinyl butyral is: 9.6:0.2:0.2:0.35:4.5:9:0.3:0.35:0.7;

[0069] (7) The casting slurry obtained in step (6) was cast using a convenient small coating machine with a blade moving speed of 30 cm / min. After drying, a thick film with a certain toughness and plasticity was formed with a thickness of about 14 μm;

[0070] (8) The thick film is cut and laminated, and then hot pressed at 35 °C and 12 MPa for 20 min to form a ceramic green body;

[0071] (9) The ceramic green body obtained in step (8) is placed in a muffle furnace for degumming, and is kept at 600 °C for 15 h to obtain a ceramic body;

[0072] (10) The degummed ceramic body is kept at 1075 °C for 20 h, and is naturally cooled to obtain a sodium bismuth titanate-based lead-free piezoelectric textured ceramic. The sample is ground and polished to a thickness of 0.4 mm;

[0073] The prepared ceramic sample is coated with silver paste with a diameter of 4 mm and a thickness of 0.4 mm, and then silver electrode sintering is performed in a muffle furnace at a silver sintering temperature of 560 °C for 20 min. After the silver electrode is sintered, the textured ceramic is polarized at an electric field of 20 kV / cm, and then the electrical properties of the sample are tested.

[0074] Comparative Example 1

[0075] The present comparative example provides a sodium bismuth titanate-based lead-free textured ceramic with high electro-mechanical response and ultra-low hysteresis and a preparation method thereof. The chemical composition of the sodium bismuth titanate-based lead-free textured ceramic is: 96wt% [99.5wt% (76mol% Bi 0.5 Na 0.5 TiO3-24mol% SrTiO3)-0.25wt% MnO-0.25wt% CuO]-4wt% SrTiO3 (only strontium titanate template), and the difference between the preparation method and Example 1 is that:

[0076] (1) In step (6), no sodium niobate template is added, and the mass ratio of the casting powder base, strontium titanate template, triolein, ethanol, butanone, dibutyl phthalate, polyethylene glycol, and polyvinyl butyral is 9.6:0.4:0.35:4.5:9:0.3:0.35:0.7.

[0077] Comparative Example 2

[0078] The present comparative example provides a sodium bismuth titanate-based lead-free textured ceramic with high electro-mechanical response and ultra-low hysteresis and a preparation method thereof. The chemical composition of the sodium bismuth titanate-based lead-free textured ceramic is: 96wt% [99.5wt% (76mol% Bi 0.5 Na 0.5 TiO3-24mol% SrTiO3)-0.25wt% MnO-0.25wt% CuO]-4wt% NaNbO3 (only sodium niobate template), and the difference between the preparation method and Example 1 is that:

[0079] (1) In step (6), no strontium titanate template is added, wherein the mass ratio of the casting powder base material, sodium niobate template, triolein, ethanol, butanone, dibutyl phthalate, polyethylene glycol and polyvinyl butyral is: 9.6:0.4:0.35:4.5:9:0.3:0.35:0.7.

[0080] Performance testing:

[0081] like Figure 1 As shown, using the Lotgering factor f The texture of Example 1 and Comparative Example 1-2 was calculated. <001> C The texture degree in the direction is 93% and 95% respectively. <001> C The texture degree in the direction is medium, which is 67%. This is because strontium titanate is one of the components of the ceramic base material (76BNT-24ST), so Example 1 and Comparative Example 1 containing strontium titanate templates have a higher texture degree.

[0082] like Figure 2 As shown in FIG1 , Example 1 has a larger grain size, and the strontium titanate template embedded in the grains can be observed; Figure 3 It can be seen that the dielectric constants of Example 1 and Comparative Examples 1-2 (the dielectric constants of Example 1 and Comparative Examples 1-2 are 4780.7, 4026.4, and 3796.6, respectively) gradually decrease with the increase of the sodium niobate template content, and both exhibit a large degree of relaxation, which is conducive to reducing hysteresis.

[0083] like Figure 4 and Figure 5 As shown, Example 1 and Comparative Examples 1-2 all exhibit ultra-low strain hysteresis, and Example 1 exhibits excellent electrostrain performance (strain=0.5%).

[0084] Therefore, the selection of the template is very important in the process of preparing the textured ceramics. Generally, the composition of the template is consistent with that of the ceramic matrix, because the chemical potential barrier between them is low, which is helpful to improve the texture degree. However, according to the previous reports and experimental data, although the pure strontium titanate template can be used to obtain a high texture degree, it is not helpful to improve the electrostrictive strain performance. On the other hand, the template which is completely different from the ceramic composition can provide the orientation degree and be doped into the ceramic matrix during the sintering process. However, it is difficult to be textured due to the high energy barrier between them. Therefore, in the present application, the strontium titanate and sodium niobate templates are mixed to obtain the high textured bismuth sodium titanate-based lead-free piezoelectric ceramics, which combines the advantages of the two templates. Meanwhile, the sodium niobate template also plays a doping role, which effectively improves the relaxation degree of the system and greatly reduces the hysteresis.

[0085] In addition, the sintering temperature of the textured ceramics is usually higher than that of the random ceramics. In the present application, the addition of the sintering aids manganese oxide and copper oxide greatly reduces the sintering temperature required for the ceramic formation. Moreover, the presence of the sintering aids forms a liquid phase during the sintering process, which is helpful to improve the texture degree.

[0086] The above description of the embodiments is for facilitating the ordinary skilled person in the art to understand and use the present application. The person skilled in the art can easily make various modifications to the embodiments and apply the general principles described herein to other embodiments without creative labor. Therefore, the present application is not limited to the above embodiments, and the improvements and modifications made by the person skilled in the art according to the disclosure of the present application without departing from the scope of the present application should be within the protection scope of the present application.

Claims

1. A sodium bismuth titanate-based lead-free textured ceramic with high electro-activity and ultra-low hysteresis, characterized in that, The ceramic has a chemical composition of 0.76Bi 0.5 Na 0.5 TiO3-0.24SrTiO3-MnO-CuO-SrTiO3-NaNbO3, The 0.76Bi 0.5 Na 0.5 TiO3-0.24SrTiO3, Bi 0.5 Na 0.5 The molar concentration of TiO3 is 76 mol% and the molar concentration of SrTiO3 is 24 mol%. The 0.76Bi 0.5 Na 0.5 TiO3-0.24SrTiO3-MnO-CuO, the mass concentration of the MnO is 0.25wt%, the mass concentration of the CuO is 0.25wt%, The 0.76Bi 0.5 Na 0.5 TiO3-0.24SrTiO3-MnO-CuO-SrTiO3-NaNbO3, the mass concentration of the SrTiO3 is 1.5-2.5wt%, and the mass concentration of the NaNbO3 is 1.5-2.5wt%. The ceramic is prepared by the following steps: S1: in accordance with the 0.76Bi 0.5 Na 0.5 TiO3-0.24SrTiO3-MnO-CuO, the sodium source, bismuth source, strontium source and titanium source are mixed, and one-time ball milling and calcination are carried out in sequence, the manganese source and copper source are added after calcination, and secondary ball milling, discharging and drying are carried out to obtain a flow casting powder base material; S2: according to the chemical composition of NaNbO3, taking bismuth source, potassium source, niobium source, and first molten salt to prepare a precursor, synthesizing the prepared precursor, potassium carbonate and the first molten salt, and filtering to obtain a sodium niobate template; S3: according to the chemical composition of SrTiO3, taking bismuth source, titanium source and second molten salt to perform ball milling and heat preservation, filtering to obtain an intermediate, ball milling strontium carbonate and third molten salt, and then adding the intermediate, and performing ball milling, heat preservation and filtering to obtain a strontium titanate template; S4: mixing the casting powder base, the sodium niobate template and the strontium titanate template according to the chemical composition of the ceramic to obtain raw powder, adding a solvent and an additive, and then sequentially performing roll milling, laminating and pressing, degassing and sintering to obtain the bismuth sodium titanate-based lead-free textured ceramic.

2. A method of preparing a sodium bismuth titanate-based lead-free textured ceramic having high electrostrictive properties and ultra-low hysteresis as claimed in claim 1, characterized in that, The method comprises the following steps: S1: in accordance with the 0.76Bi 0.5 Na 0.5 TiO3-0.24SrTiO3-MnO-CuO, the sodium source, bismuth source, strontium source and titanium source are mixed, and one-time ball milling and calcination are carried out in sequence, the manganese source and copper source are added after calcination, and secondary ball milling, discharging and drying are carried out to obtain a flow casting powder base material; S2: according to the chemical composition of NaNbO3, taking bismuth source, potassium source, niobium source, and first molten salt to prepare a precursor, synthesizing the prepared precursor, potassium carbonate and the first molten salt, and filtering to obtain a sodium niobate template; S3: according to the chemical composition of SrTiO3, taking bismuth source, titanium source and second molten salt to perform ball milling and heat preservation, filtering to obtain an intermediate, ball milling strontium carbonate and third molten salt, and then adding the intermediate, and performing ball milling, heat preservation and filtering to obtain a strontium titanate template; S4: mixing the casting powder base, the sodium niobate template and the strontium titanate template according to the chemical composition of the ceramic to obtain raw powder, adding a solvent and an additive, and then sequentially performing roll milling, laminating and pressing, degassing and sintering to obtain the bismuth sodium titanate-based lead-free textured ceramic.

3. The method of producing a sodium bismuth titanate-based lead-free textured ceramic with high electrocaloric properties and ultra-low hysteresis according to claim 2, characterized in that, In step S1, the sodium source includes sodium carbonate, the bismuth source includes bismuth trioxide, the strontium source includes strontium carbonate, the titanium source includes titanium oxide, the manganese source includes manganese oxide, and the copper source includes copper oxide.

4. The method of producing a sodium bismuth titanate-based lead-free textured ceramic with high electrocaloric properties and ultra-low hysteresis according to claim 2, characterized in that, In step S1, the temperature of the calcination is 700-900 ℃, and the calcination time is 2-4 h.

5. The method of producing a sodium bismuth titanate-based lead-free textured ceramic with high electrostrictive properties and ultra-low hysteresis according to claim 2, characterized in that, In step S2, the bismuth source includes bismuth trioxide, the potassium source includes potassium carbonate, the niobium source includes niobium pentoxide, and the first molten salt is sodium chloride.

6. The method of producing a sodium bismuth titanate-based lead-free textured ceramic with high electrocaloric properties and ultra-low hysteresis according to claim 2, characterized in that, In step S2, when the precursor is prepared, the mass ratio of the bismuth source, the potassium source, the niobium source and the first molten salt is 10: (3-3.5): (8.5-9): (24-24.2), the reaction temperature is 1000-1100 ℃, and the reaction time is 2-3 h; when the sodium niobate template is further prepared, the mass ratio of the precursor, potassium carbonate and the first molten salt is 8: (1-1.5): (10-10.5), and the synthesis temperature is 970-1000 ℃.

7. The method of producing a sodium bismuth titanate-based lead-free textured ceramic with high electrostrictive properties and ultra-low hysteresis according to claim 2, characterized in that, In step S3, the bismuth source includes bismuth trioxide, the titanium source includes titanium oxide, the second molten salt is sodium chloride and potassium chloride, and the molar ratio of sodium chloride to potassium chloride is 1:1, and the third molten salt is potassium chloride.

8. The method of producing a sodium bismuth titanate-based lead-free textured ceramic with high electrostrictive properties and ultra-low hysteresis according to claim 2, characterized in that, In step S3, when preparing the intermediate, the mass ratio of the bismuth source, the titanium source and the second molten salt is (19-20):(5-5.5):25, the temperature of the heat preservation is 1100℃, and the time of the heat preservation is 1.5h; when further preparing the strontium titanate template, the mass ratio of the strontium carbonate, the third molten salt ball mill and the intermediate is (6.5-7):(18-18.5):(11.5-12).

9. The method of producing a sodium bismuth titanate-based lead-free textured ceramic with high electrostrictive properties and ultra-low hysteresis according to claim 2, characterized in that, In step S4, the solvent includes one or a mixture of the two of butanone and ethanol, and the auxiliary includes a dispersant, a plasticizer and a binder. The dispersant includes glycerol trioleate, the plasticizer includes one or a mixture of the two of polyethylene glycol and dibutyl phthalate, and the binder includes polyvinyl butyral.

10. The method of producing a sodium bismuth titanate-based lead-free textured ceramic with high electrocaloric properties and ultra-low hysteresis according to claim 9, characterized in that, In step S4, the mass ratio of the raw material powder, the solvent, the dispersant, the plasticizer and the binder is 10:13.5:(0.3-0.4):0.65:0.7.

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