A sodium bismuth titanate-based relaxor ferroelectric material with high electro-strain, low hysteresis and high temperature stability and a preparation method thereof

Abstract

The application discloses a sodium bismuth titanate-based relaxor ferroelectric material with high electro-strain, low hysteresis and high temperature stability and a preparation method thereof, and belongs to the technical field of functional materials. (0.47‑x) Li x / 2 K x / 2 Bi 0.47 Ba 0.06 TiO3, wherein 0.06<=x<=0.10. The material has high electro-strain, low hysteresis and high temperature stability, and is suitable for micro displacement devices. The preparation method comprises the following steps: weighing raw materials according to stoichiometric ratios, ball milling, drying, grinding, calcining, ball milling again, drying and grinding again; adding a binder to granulate and sinter to obtain ceramic sheets; and polishing the ceramic sheets and electroplating silver on surfaces of the ceramic sheets. The method is simple, low in cost and suitable for large-scale production.

Description

Technical Field

[0001] This invention belongs to the field of functional materials technology, and particularly relates to a sodium bismuth titanate-based relaxor ferroelectric material with high electrostrain, low hysteresis, and high temperature stability, and its preparation method. Background Technology

[0002] Piezoelectric ceramics, as key smart materials in modern electronic devices, have their electrostrain properties (such as strain value, hysteresis effect, and temperature stability) as crucial indicators. Their excellent electrostrain characteristics have demonstrated significant advantages in micro-displacement devices such as precision actuators, sensors, and transducers. These devices feature fast response, electromagnetic interference resistance, low energy consumption, and lightweight design, and have been successfully applied in important fields such as biomedicine, nano-positioning, and aerospace. Currently, the mainstream commercially available material is lead zirconate titanate (PZT), but the lead pollution generated during its preparation and use seriously threatens the ecological environment and human health. Furthermore, industrial technological development places higher demands on piezoelectric materials, urgently requiring higher precision strain output over a wide dynamic range. Therefore, the development of high-performance lead-free piezoelectric ceramics has become an important research direction in this field.

[0003] In current lead-free piezoelectric material systems, sodium bismuth titanate (Bi) 0.5 Na 0.5 TiO3 (BNT)-based relaxor ferroelectric ceramics have attracted much attention due to their ability to achieve high electrostriction through phase boundary modulation. However, existing technologies suffer from bottlenecks such as large strain hysteresis (>60%) and poor temperature stability, limiting their application in electrostricted materials. To address this, current methods primarily involve the synthesis of sodium bismuth titanate-based relaxor ferroelectrics through component solid solution and ion substitution. However, an electrostricted material possessing high electrostriction, low hysteresis, and high temperature stability has yet to be discovered.

[0004] Existing technologies mostly rely on a single optimization strategy. Therefore, there is an urgent need for a new material design and preparation method that can maintain the high strain characteristics of BNT-based ceramics while achieving low hysteresis and high temperature stability, so as to meet the urgent demand for high-performance lead-free piezoelectric ceramics in fields such as precision actuators. Summary of the Invention

[0005] To address the aforementioned technical problems, this invention proposes a sodium bismuth titanate-based relaxor ferroelectric material and its preparation method, which possesses high electrostriction, low hysteresis, and high temperature stability.

[0006] To achieve the above objectives, the present invention provides the following technical solution:

[0007] One objective of this invention is to provide a sodium bismuth titanate-based relaxor ferroelectric material that combines high electrostrain, low hysteresis, and high temperature stability, with the chemical composition: Na (0.47-x) Li x / 2 Kx / 2 Bi 0.47 Ba 0.06 TiO3, where x = 0.06 or 0.08.

[0008] This invention discloses a sodium bismuth titanate-based relaxor ferroelectric material with high electrostrain, low hysteresis, and high temperature stability through half-A-site ion substitution, namely Na (0.47-x) Li x / 2 K x / 2 Bi 0.47 Ba 0.06 TiO3 relaxor ferroelectric ceramics. Li + With K + Having the same properties as Na + For the same valence state, their average ionic radius (Li + : K + : Na + : ) and Na + Approximately. Using a stoichiometric ratio of 1:1 for Li... + -K + Cooperative replacement of Na + (Half-A-site substitution) can maximize lattice stability, avoid MPB structure distortion, and improve strain temperature stability; at the same time, the local chemical disorder at the A-site (Li) + / K + / Na + / Bi 3+ (Coexistence) can shift the FE-RFE and ER-NR phase boundary to near room temperature, significantly reducing hysteresis. Based on this, the present invention proposes a multi-ion half-A-site substitution strategy, through Li + -K + By synergistically regulating the MPB phase boundary and ER / NR domain structure, continuous optimization of electrostrain and hysteresis is achieved without compromising ferroelectric activity. This co-doping strategy effectively reduces hysteresis while improving temperature stability. By adjusting the value of x, the material's properties can be precisely controlled, allowing it to exhibit optimal performance in various applications. The electrostrain value can reach above 0.5%, the hysteresis is stable below 25%, and the strain-temperature change rate (Smax, T / Smax, RT) is less than 20% in the range from room temperature to 110℃. Furthermore, the strain value of the x = 0.06 component reaches 0.68% at 160 kV / cm, while the hysteresis of the x = 0.08 component is approximately 14%.

[0009] Furthermore, x is 0.06 or 0.08.

[0010] Different x values ​​correspond to different Li values + and K +The doping ratio affects the crystal structure and electrical properties of the material. Experiments have shown that these specific x values ​​enable the material to achieve an optimal balance between electrostrain, hysteresis, and temperature stability. At x = 0.08, the material exhibits a low hysteresis (approximately 14%) and a high strain value (0.62%).

[0011] Furthermore, x is 0.08.

[0012] When x = 0.08, Li + and K + The optimal co-doping ratio optimizes the material's crystal structure and electrical properties. At this level, the material exhibits high electrostrain, low hysteresis, and good temperature stability. This composition holds significant potential for application in micro-displacement devices.

[0013] The second objective of this invention is to provide a method for preparing sodium bismuth titanate-based relaxor ferroelectric materials that possess high electrostrain, low hysteresis, and high temperature stability. This invention uses NBT-6BT as a matrix and utilizes Li at the half-A sites... + / K + A co-doping strategy was used to design and prepare Na (0.47-x) Li x / 2 K x / 2 Bi 0.47 Ba 0.06 TiO3 is synthesized using a solid-state reaction method, specifically including the following steps:

[0014] S1. Weigh Na2CO3, Li2CO3, K2CO3, Bi2O3, BaCO3, and TiO2 according to the stoichiometric ratio, mix them with ethanol, and ball mill them. Then, dry, grind, pre-calcine, and cool them in sequence. After that, add ethanol to the cooled sample again and ball mill it. Then, dry and grind it in sequence.

[0015] S2. Add a binder to the sample obtained in step S1, grind, granulate, and sinter to obtain a ceramic sheet;

[0016] S3. The ceramic sheet is polished and silver is electroplated on the upper and lower surfaces to obtain a sodium bismuth titanate-based relaxor ferroelectric material with high electrostriction, low hysteresis, and high temperature stability.

[0017] The ball milling process uses mechanical force to thoroughly mix the raw materials, forming a homogeneous precursor. The pre-calcination process uses high-temperature treatment to induce a chemical reaction in the raw materials, forming the target compound. The granulation and sintering steps further optimize the microstructure of the material, improving its density and electrical properties. By precisely controlling the parameters of these steps, the high quality and consistency of the material can be ensured.

[0018] Furthermore, in step S1, the ball milling time is 10-14 hours.

[0019] The duration of ball milling directly affects the uniformity of raw material mixing and the quality of the precursor. A ball milling time of 10-14 hours ensures that the raw materials are fully mixed to form a uniform precursor, thereby improving the material's performance.

[0020] Furthermore, in step S1, the amount of ethanol used can be freely selected according to the volume of the container used and the uniformity of grinding, as long as it is conducive to uniform grinding, and the ethanol will gradually evaporate during subsequent processing.

[0021] Further, in step S1, the specific operation steps of the pre-firing are as follows: the temperature is increased to 850-880℃ at a heating rate of 5℃ / min, and the temperature is maintained at this temperature for 3 hours.

[0022] The heating rate and holding temperature during the pre-calcination process have a significant impact on the crystal structure and electrical properties of the material. Heating to 850-880℃ at a heating rate of 5℃ / min and holding for 3 hours can ensure that the raw materials react fully and form a high-quality target compound.

[0023] Further, in step S2, the mass ratio of the adhesive to the sample is 1:(5-10).

[0024] Furthermore, the adhesive is polyvinyl alcohol (PVA).

[0025] The amount and type of binder have a significant impact on the granulation and sintering process. Polyvinyl alcohol (PVA), as a commonly used binder, can effectively improve the moldability and sintering quality of samples. A mass ratio of 1:(5-10) ensures that the amount of binder is appropriate, neither too much affecting the material properties nor too little causing molding difficulties.

[0026] Further, in step S2, the specific operation steps of sintering are as follows: heating to 600°C at a heating rate of 5°C / min and holding for 2 hours, then heating to 1130-1160°C and holding for 2-3 hours.

[0027] The heating rate and holding temperature during sintering have a significant impact on the microstructure and electrical properties of the material. Heating to 600℃ at a rate of 5℃ / min and holding for 2 hours, followed by heating to 1130-1160℃ and holding for 2-3 hours, can ensure the formation of a dense microstructure during sintering and improve its electrical properties.

[0028] A third objective of this invention is to provide an application of sodium bismuth titanate-based relaxor ferroelectric material, which combines high electrostrain, low hysteresis, and high temperature stability, in micro-displacement devices, such as precision actuators, sensors, and transducers.

[0029] The material's high electrostriction, low hysteresis, and high temperature stability make it a significant advantage in micro-displacement devices such as precision actuators, sensors, and transducers. These properties meet the urgent need for high-performance lead-free piezoelectric ceramics in modern electronic devices.

[0030] Compared with the prior art, the present invention has the following advantages and technical effects:

[0031] The sodium bismuth titanate-based relaxor ferroelectric material provided by this invention possesses high electrostriction, low hysteresis, and high temperature stability, making it widely applicable to micro-displacement devices such as precision actuators, sensors, and transducers. The preparation method of this invention is simple, low-cost, and suitable for large-scale production, which will facilitate its related applications.

[0032] This material is inexpensive, simple to prepare, environmentally friendly, has a long service life, and can be mass-produced, making it a promising replacement for other electrostrained ceramic materials. Currently, there is no existing technology related to Na… (0.47-x) Li x / 2 K x / 2 Bi 0.47 Ba 0.06 Reports on TiO3 relaxor ferroelectric ceramics. Attached Figure Description

[0033] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings:

[0034] Figure 1 SEM images of sodium bismuth titanate-based relaxor ferroelectric materials prepared in Examples 1 and 2 of the present invention are shown, wherein (a) is the SEM image of Example 1, (b) is the SEM image of Example 2, (c) is the grain size of Example 1, and (d) is the grain size of Example 2.

[0035] Figure 2 The electro-induced strain hysteresis calculation method in Embodiments 1 and 2 of the present invention;

[0036] Figure 3 The bipolar strain curves of sodium bismuth titanate-based relaxor ferroelectric materials prepared in Examples 1 and 2 of the present invention at room temperature are shown, where (a) is Example 1 and (b) is Example 2.

[0037] Figure 4The curves showing the unipolar strain versus temperature of the sodium bismuth titanate-based relaxor ferroelectric materials prepared in Examples 1 and 2 of this invention are shown, where (a) is Example 1 and (b) is Example 2.

[0038] Figure 5 The bipolar strain curves at room temperature of the sodium bismuth titanate-based relaxor ferroelectric material prepared in Comparative Example 1 are shown. Detailed Implementation

[0039] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as a limitation of the present invention, but rather as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0040] It should be understood that the terminology used in this invention is merely for describing particular embodiments and is not intended to limit the invention. Furthermore, with respect to numerical ranges in this invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Every smaller range between any stated value or intermediate value within a stated range, and any other stated value or intermediate value within said range, is also included in this invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0041] Unless otherwise stated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. While only preferred methods and materials have been described herein, any methods and materials similar or equivalent to those described herein may be used in the implementation or testing of this invention. All references to this specification are incorporated by way of citation to disclose and describe methods and / or materials associated with those references. In the event of any conflict with any incorporated reference, the content of this specification shall prevail.

[0042] Various modifications and variations can be made to the specific embodiments described in this specification without departing from the scope or spirit of the invention, as will be apparent to those skilled in the art. Other embodiments derived from this specification will also be readily apparent to those skilled in the art. This specification and embodiments are merely exemplary.

[0043] The terms “include,” “including,” “have,” “contain,” etc., used in this article are all open-ended terms, meaning that they include but are not limited to.

[0044] This invention provides a sodium bismuth titanate-based relaxor ferroelectric material with high electrostrain, low hysteresis, and high temperature stability, with the chemical composition: Na (0.47-x) Li x / 2 K x / 2 Bi 0.47 Ba 0.06TiO3, wherein 0.06≤x≤0.10. For example, x can be selected as 0.06, 0.07, 0.08, 0.09 or 0.10, and x is preferably 0.08.

[0045] The preparation method of the sodium bismuth titanate-based relaxor ferroelectric material, which possesses high electrostrain, low hysteresis, and high temperature stability, includes the following steps:

[0046] S1. Weigh out Na2CO3 (99.8%), Li2CO3 (99.8%), K2CO3 (99.8%), Bi2O3 (99.8%), BaCO3 (99%), and TiO2 (99%) according to the stoichiometric ratio, mix with ethanol, and ball mill. Then, dry, grind, calcine, and cool in sequence. Subsequently, add ethanol to the cooled sample again, ball mill, and then dry and grind in sequence.

[0047] S2. Add a binder to the sample obtained in step S1, grind, granulate, and sinter to obtain a ceramic sheet;

[0048] S3. Polish the ceramic sheet and electroplate silver on the upper and lower surfaces to obtain a sodium bismuth titanate-based relaxor ferroelectric material with high electrostriction, low hysteresis, and high temperature stability.

[0049] In some optional embodiments of the present invention, the ball milling time in step S1 is 10-14 hours. Exemplarily, in the following preferred embodiments of the present invention, the ball milling time is 12 hours.

[0050] In some optional embodiments of the present invention, in step S1, the amount of ethanol can be freely selected according to the volume of the container used and the uniformity of grinding, as long as it is conducive to uniform grinding, and the ethanol will gradually evaporate during subsequent processing.

[0051] In some optional embodiments of the present invention, the specific operation steps of calcination in step S1 are as follows: heating to 850-880°C at a heating rate of 5°C / min, and holding at this temperature for 3 hours. Exemplarily, in the following preferred embodiments of the present invention, the calcination temperature is 850°C.

[0052] In some optional embodiments of the present invention, in step S2, the mass ratio of the adhesive to the sample is 1:(5-10). Exemplarily, in the following preferred embodiments of the present invention, the mass ratio of the adhesive to the sample is 1:10. The adhesive is polyvinyl alcohol (PVA).

[0053] In some optional embodiments of the present invention, the grinding time in step S2 is 1 hour.

[0054] In some optional embodiments of the present invention, the specific operation steps of sintering in step S2 are as follows: heating to 600°C at a heating rate of 5°C / min and holding at that temperature for 2 hours, followed by heating to 1130-1160°C and holding at that temperature for 2-3 hours. Exemplarily, in the following preferred embodiments of the present invention, the temperature after heating is 1140°C and held at that temperature for 2 hours.

[0055] In the following preferred embodiment of the present invention, in step S3, the ceramic sheet is polished to 0.3 mm.

[0056] The sodium bismuth titanate-based relaxor ferroelectric material provided by this invention, which combines high electrostriction, low hysteresis, and high temperature stability, can be applied in micro displacement devices.

[0057] Unless otherwise specified, "room temperature" in this invention refers to 25±2℃.

[0058] All raw materials used in this invention were purchased from the market.

[0059] The technical solution of the present invention will be further illustrated by the following embodiments.

[0060] Example 1

[0061] A sodium bismuth titanate-based relaxor ferroelectric material (Na) possessing high electrostrain, low hysteresis, and high temperature stability 0.41 Li 0.03 K 0.03 Bi 0.47 Ba 0.06 The preparation method of TiO3 (i.e., x = 0.06) includes the following steps:

[0062] S1. Weigh 3.92047g of Na2CO3, 0.19506g of Li2CO3, 0.36673g of K2CO3, 19.75771g of Bi2O3, 2.09452g of BaCO3, and 14.12075g of TiO2 according to the stoichiometric ratio. Pour them into a ball mill jar, add ethanol, and ball mill for 12 hours. Dry the ball-milled sample, then sieve the dried solid slurry through a 100-mesh sieve to obtain sample powder. Place the powder in a muffle furnace and calcine at 850℃ for 3 hours at a heating rate of 5℃ / min. Cool the powder. Then pour the cooled sample into a ball mill jar, add ethanol, and ball mill for a second time for 12 hours. Dry the ball-milled sample, then sieve the dried solid slurry through a 100-mesh sieve to obtain sample powder.

[0063] S2. Pour the sample powder obtained in step S1 into a mortar, add polyvinyl alcohol (the mass ratio of polyvinyl alcohol to sample is 1:10) and grind for 1 hour. After grinding evenly, pour it into a mold with φ=10mm and press it into a sheet. Then put it into a muffle furnace and set the temperature to 600℃ and keep it at that temperature for 2 hours to remove the glue. Then raise the temperature to 1140℃ and calcine for 2 hours at a heating rate of 5℃ / min. After cooling in the furnace, ceramic sheets are obtained.

[0064] S3. Grind the ceramic sheet to a thickness of 0.3 mm, and electroplate the upper and lower surfaces with silver (the silver plating diameter on the upper surface is 4 mm, and the silver plating diameter on the lower surface is 6 mm) to obtain a sodium bismuth titanate-based relaxor ferroelectric material with high electrostriction, low hysteresis, and high temperature stability.

[0065] Example 2

[0066] A sodium bismuth titanate-based relaxor ferroelectric material (Na) possessing high electrostrain, low hysteresis, and high temperature stability 0.39 Li 0.04 K 0.04 Bi 0.47 Ba 0.06 The preparation method of TiO3 (i.e., x = 0.08) includes the following steps:

[0067] S1. Weigh 3.72922g of Na2CO3, 0.26141g of Li2CO3, 0.48897g of K2CO3, 19.75766g of Bi2O3, 2.09452g of BaCO3, and 14.12871g of TiO2 according to the stoichiometric ratio, pour them into a ball mill jar, add ethanol and ball mill for 12 hours. Dry the ball-milled sample, and then sieve the dried solid slurry through a 100-mesh sieve to obtain sample powder. Then place it in a muffle furnace and calcine at 850℃ for 3 hours with a heating rate of 5℃ / min, and cool it. Then pour the cooled sample into a ball mill jar, add ethanol and ball mill for a second time for 12 hours. Dry the ball-milled sample, and then sieve the dried solid slurry through a 100-mesh sieve to obtain sample powder.

[0068] S2. Pour the sample obtained in step S1 into a mortar, add polyvinyl alcohol (the mass ratio of polyvinyl alcohol to the sample is 1:10) and grind for 1 hour. After grinding evenly, pour it into a mold with φ=10mm and press it into a sheet. Then put it into a muffle furnace and set the temperature to 600℃ and keep it at that temperature for 2 hours to remove the glue. Then raise the temperature to 1140℃ and calcine for 2 hours at a heating rate of 5℃ / min. After cooling in the furnace, ceramic sheets are obtained.

[0069] S3. Grind the ceramic sheet to a thickness of 0.3 mm, and electroplate the upper and lower surfaces with silver (the silver plating diameter on the upper surface is 4 mm, and the silver plating diameter on the lower surface is 6 mm) to obtain a sodium bismuth titanate-based relaxor ferroelectric material with high electrostriction, low hysteresis, and high temperature stability.

[0070] Figure 1 The images show SEM images of the sodium bismuth titanate-based relaxor ferroelectric materials prepared in Examples 1 and 2 of this invention. (a) is the SEM image of the sodium bismuth titanate-based relaxor ferroelectric material obtained in Example 1, (b) is the SEM image of the sodium bismuth titanate-based relaxor ferroelectric material obtained in Example 2, (c) shows the grain size of the sodium bismuth titanate-based relaxor ferroelectric material obtained in Example 1, and (d) shows the grain size of the sodium bismuth titanate-based relaxor ferroelectric material obtained in Example 2. Figure 1 As can be seen, the grain size of this material is around 0.7 μm, and it has a high density.

[0071] Figure 2 This describes the electroinduced strain hysteresis calculation methods in Embodiments 1 and 2 of the present invention. The left figure is a schematic diagram of hysteresis calculation for bipolar strain; H1 represents the strain calculation method under a negative electric field, and H2 represents the strain calculation method under a positive electric field; S 1- S represents the strain magnitude corresponding to the unloading electric field process under a negative half electric field. 2- S represents the strain magnitude corresponding to the process of applying an electric field under a negative half electric field. 1+ S represents the strain magnitude corresponding to the unloading electric field process under a positive half-electric field. 2+ S represents the strain magnitude corresponding to the process of applying an electric field under a positive half-electric field; max- This represents the maximum strain corresponding to the negative maximum electric field; S max+ S1 represents the maximum strain under the negative maximum electric field; E is the electric field strength; the right figure is a schematic diagram of the hysteresis calculation of unipolar strain; S1 is the strain magnitude corresponding to the loading electric field process under half the electric field; S2 is the strain magnitude corresponding to the unloading electric field process under half the electric field; S max The maximum strain corresponding to the negative maximum electric field.

[0072] Figure 3 The figures show the bipolar strain curves at room temperature of the sodium bismuth titanate-based relaxor ferroelectric materials prepared in Examples 1 and 2 of this invention, where (a) is Example 1 and (b) is Example 2. The testing method was as follows: a sample with a thickness of 0.3 mm and double-sided silver plating was used, and its JE curve was measured at a frequency of 1 Hz using ferroelectric analysis combined with a laser interferometer vibrometer. Figure 3As can be seen from the results, the maximum load electric field of the ceramic in Example 1 can reach 160KV / cm, the strain value can reach 0.68%, and the hysteresis rate is calculated to be 24%; the maximum load electric field of the ceramic in Example 2 can reach 160KV / cm, the strain value can reach 0.62%, and the hysteresis rate is calculated to be 14%.

[0073] Figure 4 The figures show the unipolar strain versus temperature curves of the sodium bismuth titanate-based relaxor ferroelectric materials prepared in Examples 1 and 2 of this invention, where (a) is Example 1 and (b) is Example 2. The testing method was as follows: a sample with a thickness of 0.3 mm and double-sided silver plating was used. The JE curve was measured at a frequency of 1 Hz using ferroelectric analysis combined with a laser interferometer vibrometer. Subsequently, the temperature was increased at a rate of 10 °C under an electric field of 120 kV / cm. The results are as follows. Figure 4 As shown. From Figure 4 It can be seen that as the temperature increases from room temperature to 110℃, the strain change rate is less than 20%.

[0074] Comparative Example 1

[0075] A type (75B) 0.5 Na 0.5 The preparation method of TiO3-25SrTiO3 (i.e., NBT-25ST) includes the following steps:

[0076] S1. Weigh 3.65675g of Na2CO3, 16.07605g of Bi2O3, 6.24579g of SrCO3, and 14.40831g of TiO2 according to the stoichiometric ratio, pour them into a ball mill jar, add ethanol, and ball mill for 12 hours. Dry the milled sample, and then sieve the dried solid slurry through a 100-mesh sieve to obtain sample powder. Then, calcine the sample in a muffle furnace at 900℃ for 3 hours at a heating rate of 5℃ / min, and cool it. After cooling, pour the sample into a ball mill jar, add ethanol, and ball mill again for 12 hours. Dry the milled sample, and then sieve the dried solid slurry through a 100-mesh sieve to obtain sample powder.

[0077] S2. Pour the sample obtained in step S1 into a mortar, add polyvinyl alcohol (the mass ratio of polyvinyl alcohol to the sample is 1:10) and grind for 1 hour. After grinding evenly, pour it into a mold with φ=10mm and press it into a sheet. Then put it into a muffle furnace and set the temperature to 600℃ and keep it at that temperature for 2 hours to remove the glue. Then raise the temperature to 1115℃ and calcine for 3 hours at a heating rate of 5℃ / min. After cooling in the furnace, ceramic sheets are obtained.

[0078] S3. Grind the ceramic sheet to a thickness of 0.3mm, and electroplate the upper and lower surfaces with silver (the silver plating diameter on the upper surface is 4mm, and the silver plating diameter on the lower surface is 6mm).

[0079] Figure 5 The image shows the bipolar strain curves at room temperature of the sodium bismuth titanate-based relaxor ferroelectric material prepared in Comparative Example 1. Figure 5 As can be seen, the maximum electric field of the load is 80 kV / cm, the ceramic strain value of Comparative Example 1 is 0.27%, and the hysteresis rate is calculated to be 48%.

[0080] The above are merely preferred embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A sodium bismuth titanate-based relaxor ferroelectric material possessing high electrostrain, low hysteresis, and high temperature stability, characterized in that, The chemical composition is: Na (0.47-x) Li x / 2 K x / 2 Bi 0.47 Ba 0.06 TiO3, wherein x is 0.06 or 0.

08.

2. The sodium bismuth titanate-based relaxor ferroelectric material with high electrostrain, low hysteresis, and high temperature stability as described in claim 1, characterized in that, The value of x is 0.

08.

3. A method for preparing a sodium bismuth titanate-based relaxor ferroelectric material with high electrostriction, low hysteresis, and high temperature stability as described in any one of claims 1-2, characterized in that, Includes the following steps: S1. Weigh Na2CO3, Li2CO3, K2CO3, Bi2O3, BaCO3, and TiO2 according to the stoichiometric ratio, mix them with ethanol, and ball mill them. Then, dry, grind, pre-calcine, and cool them in sequence. After that, add ethanol to the cooled sample again and ball mill it. Then, dry and grind it in sequence. S2. Add a binder to the sample obtained in step S1, grind, granulate, and sinter to obtain a ceramic sheet; S3. Polish the ceramic sheet and electroplate silver on the upper and lower surfaces to obtain the sodium bismuth titanate-based relaxor ferroelectric material with high electrostriction, low hysteresis, and high temperature stability.

4. The method for preparing the sodium bismuth titanate-based relaxor ferroelectric material with high electrostrain, low hysteresis, and high temperature stability according to claim 3, characterized in that, In step S1, the ball milling time is 10-14 hours.

5. The method for preparing the sodium bismuth titanate-based relaxor ferroelectric material with high electrostrain, low hysteresis, and high temperature stability according to claim 3, characterized in that, In step S1, the specific operation steps of the pre-firing are as follows: heat up to 850-880°C at a heating rate of 5°C / min, and keep at this temperature for 3 hours.

6. The method for preparing the sodium bismuth titanate-based relaxor ferroelectric material with high electrostrain, low hysteresis, and high temperature stability according to claim 3, characterized in that, In step S2, the mass ratio of the adhesive to the sample is 1:(5-10).

7. The method for preparing the sodium bismuth titanate-based relaxor ferroelectric material with high electrostrain, low hysteresis, and high temperature stability according to claim 6, characterized in that, The adhesive is polyvinyl alcohol.

8. The method for preparing the sodium bismuth titanate-based relaxor ferroelectric material with high electrostrain, low hysteresis, and high temperature stability according to claim 3, characterized in that, In step S2, the specific sintering operation steps are as follows: heat up to 600°C at a heating rate of 5°C / min and hold for 2 hours, then heat up to 1130-1160°C and hold for 2-3 hours.

9. The application of a sodium bismuth titanate-based relaxor ferroelectric material with high electrostriction, low hysteresis, and high temperature stability as described in any one of claims 1-2 in micro displacement devices.

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