A sodium bismuth titanate-based lead-free relaxor ferroelectric energy storage ceramic material with antiferroelectric-like properties and a preparation method thereof

Abstract

This invention discloses a lead-free relaxor ferroelectric energy storage ceramic material based on sodium bismuth titanate with antiferroelectric-like properties and its preparation method. The ceramic material comprises materials using the general formula (1-x)(Na... 0.3 Bi 0.38 Sr 0.28 TiO3)-xBi(Mg 0.5 Zr 0.5 The term "(x)" represents a lead-free relaxor ferroelectric energy storage ceramic material based on bismuth sodium titanate with antiferroelectric-like properties, where x ranges from 0 to 0.2. This invention utilizes a synergistic optimization strategy to regulate the structure from multiple dimensions, resulting in a lead-free relaxor ferroelectric energy storage ceramic material with extremely low hysteresis loss and antiferroelectric-like properties. Its hysteresis loop exhibits a slender, waisted shape and increases with the change in Bi(Mg) content. 0.5 Zr 0.5 The increased O3 content significantly increased the waist-binding effect. Simultaneously, Bi(Mg) 0.5 Zr 0.5 The increased O3 content significantly improves the breakdown electric field of the ceramic material and delays polarization saturation, thereby greatly improving its energy storage performance and enabling it to simultaneously achieve high energy density and efficiency. This invention addresses, to some extent, the problems of low energy density and mismatch between energy density and efficiency in dielectric materials, providing a preparation method and material selection for developing environmentally friendly dielectric energy storage ceramic capacitors that combine high energy density and efficiency.

Description

Technical Field

[0001] This invention belongs to the field of electronic information functional materials and devices technology, specifically relating to a sodium bismuth titanate-based lead-free relaxor ferroelectric energy storage ceramic material with antiferroelectric-like properties and its preparation method. Background Technology

[0002] Due to their ultra-high power density, ultra-fast charge and discharge speeds, and excellent energy storage stability, dielectric energy storage ceramic capacitors have broad application prospects in military, civilian, and commercial fields, such as electromagnetic railguns, electromagnetic catapults, green intermittent energy storage, pulsed power systems, power grid systems, hybrid electric vehicles, and medical equipment. However, their relatively low energy storage density and the mismatch between energy storage density and efficiency severely limit their application and development. For dielectric energy storage ceramic capacitors, the key to their energy storage performance lies in their underlying core material, namely the dielectric material (ceramic). Furthermore, in recent years, electronic components have been continuously developing towards lead-free, miniaturized, lightweight, and integrated designs. Therefore, developing high-performance lead-free ceramic dielectrics to fundamentally solve the aforementioned problems has become a research hotspot in the field of materials science in recent years, possessing significant practical and strategic importance.

[0003] Due to their large spontaneous polarization, strong dielectric relaxation characteristics, and wide dielectric tunability and stability, research on sodium bismuth titanate-based lead-free relaxor ferroelectrics has been booming in recent years. Research on sodium bismuth titanate-based lead-free relaxor ferroelectrics can be divided into two main categories. The first is conventional relaxor ferroelectrics, such as those reported in *Ceramics International* (DOI: 10.1016 / j.ceramint.2021.12.171) and the Chinese patent "A Sodium Bismuth Titanate-Based Lead-Free Relaxor Ferroelectric Energy Storage Ceramic Material and Its Preparation Method" (Application No.: CN202311067754.4). The second is relaxor ferroelectrics with antiferroelectric-like properties, such as those reported in *Applied Physics Letters* (DOI: 10.1063 / 1.4950974) and *Journal of Matriomics* (DOI: 10.1016 / j.jmat.2022.01.007). Compared to the former, the latter exhibits a waisted hysteresis loop with antiferroelectric-like properties, giving it a greater advantage in energy storage and making it a potential key material for developing ceramic capacitors with both high energy density and efficiency. Although there have been reports in recent years on sodium bismuth titanate-based lead-free relaxor ferroelectrics with antiferroelectric-like properties, such as in Rare Metals (DOI: 10.1007 / s12598-022-02176-x) and Small (DOI: 10.1002 / smll.202302346), there are still relatively few reports and technological achievements on sodium bismuth titanate-based lead-free relaxor ferroelectric energy storage ceramic materials with antiferroelectric-like properties and their preparation methods. These are far fewer than the research on conventional relaxor ferroelectrics, which means that there is still much room for improvement in this type of research. Summary of the Invention

[0004] The purpose of this invention is to address the problems existing in the background technology by proposing a lead-free relaxor ferroelectric energy storage ceramic material based on sodium bismuth titanate with antiferroelectric-like properties and its preparation method. Through a synergistic optimization strategy, the structure is regulated from multiple dimensions to ultimately achieve both high releasable energy storage density and efficiency.

[0005] The objective of this invention can be achieved through the following technical solutions: A lead-free relaxor ferroelectric energy storage ceramic material based on sodium bismuth titanate with antiferroelectric-like properties, comprising the use of the general formula (1-x)(Na 0.3 Bi 0.38 Sr 0.28 TiO3)-xBi(Mg 0.5 Zr 0.5 )O3 (hereinafter abbreviated as: NBST-BMZ) represents a lead-free relaxor ferroelectric energy storage ceramic material based on sodium bismuth titanate with antiferroelectric-like properties, wherein x ranges from 0 to x ≤ 0.2.

[0006] Preferably, x = 0.15 in the ceramic material.

[0007] This invention uses Na 0.3 Bi 0.38 Sr 0.28 Using TiO3 relaxor ferroelectric as a matrix, and doped with bismuth-containing complex ions Bi(Mg) 0.5 Zr 0.5 ) 6+ By entering the matrix, multi-dimensional synergistic optimization and control of the ceramic material structure can be achieved, with the aim of simultaneously achieving high releasable energy storage density and efficiency. The specific principle is as follows: Bismuth complex ion Bi(Mg) 0.5 Zr 0.5 ) 6+ Doping, and slightly excess Bi₂O₃ and Na₂CO₃ during weighing, can reduce oxygen vacancy production, lower oxygen vacancy concentration, suppress high-temperature mass transfer processes, reduce grain size, increase grain boundary quantity, and improve the breakdown electric field; due to the large band gap of Mg... 2+ and Zr 4+ The introduction of this technology also improves the insulation properties of NBST-BMZ ceramic materials and further enhances their breakdown electric field.

[0008] Furthermore, the introduction of ions with different valence states and radii modulates the evolution of the phase structure and stabilizes the multiphase coexistence state; this leads to lattice distortion and charge imbalance, enhancing the structural disorder of NBST-BMZ ceramic materials, resulting in an increased local random field and a decreased anisotropic field. The enhancement of the local random field disrupts the long-range ordered structure of ferroelectrics, promoting the evolution of ferroelectric macrodomains into short-range ordered microdomains and / or polar nanodomains; the decrease in the anisotropic field flattens the free energy and lowers the free energy barrier between phases.

[0009] Furthermore, the introduction of ions with different valence states and radii induces the defect dipole pinning domain wall effect, increases the domain flipping field and provides restoring force for domain rotation, which manifests as the hysteresis loop transforming into a waisted or antiferroelectric type and is accompanied by the generation of saturation polarization delay.

[0010] Furthermore, thanks to the synergistic effects of grain size, band gap, local random field, anisotropic field, and defect dipole, the insulation properties of NBST-BMZ ceramic materials were improved and the breakdown electric field was increased. The domain structure was refined and the interdomain coupling was weakened. The phase structure evolution was regulated and the multiphase coexistence state was stabilized. The domain flipping barrier was reduced and the domain response rate was accelerated, promoting domain flipping and rotation (polarization expansion and recovery). The relaxation characteristics were enhanced and the polarization saturation was delayed. Finally, a lead-free relaxor ferroelectric energy storage ceramic material based on sodium bismuth titanate with antiferroelectric-like properties was obtained, which has both high releasable energy storage density and efficiency.

[0011] Furthermore, in this invention, x is in the range of 0 ≤ x ≤ 0.2, and within this range, the energy storage density of NBST-BMZ ceramic material can reach 2~5 J / cm³. 3 The energy storage efficiency can reach 80-95%; thanks to the above synergistic effect, with x=0.15 preferred, the maximum releaseable energy storage density of this component is 5 J / cm³. 3 The energy storage efficiency is 90%.

[0012] A method for preparing a lead-free relaxor ferroelectric energy storage ceramic material based on sodium bismuth titanate with antiferroelectric-like properties includes using the general formula (1-x)(Na 0.3 Bi 0.38 Sr 0.28 TiO3)-xBi(Mg 0.5 Zr 0.5 A method for preparing a sodium bismuth titanate-based lead-free relaxor ferroelectric energy storage ceramic material with antiferroelectric-like properties, represented by O3 (hereinafter abbreviated as NBST-BMZ), wherein x ranges from 0 to x ≤ 0.2, and the preparation method of the ceramic material includes the following steps: S1: Select Na2CO3, Bi2O3, Sr2CO3, TiO2, MgO, and ZrO2 with a purity of not less than 98% as raw materials, and follow the general formula (1-x)(Na 0.3 Bi 0.38 Sr 0.28 TiO3)-xBi(Mg 0.5 Zr 0.5 The stoichiometric ratio of O3 is weighed, and NBST-BMZ ceramic powder is obtained through ball milling, pre-sintering and crushing. S2: The NBST-BMZ ceramic powder obtained in step S1 is uniformly mixed with solvent, dispersant, binder and defoamer to obtain NBST-BMZ ceramic slurry, NBST-BMZ thick film is obtained by casting process, and NBST-BMZ ceramic green body is obtained by lamination hot pressing process. S3: The NBST-BMZ ceramic green body obtained in step S2 is subjected to debinding and sintering treatment to obtain NBST-BMZ ceramic with antiferroelectric properties.

[0013] Furthermore, the amount of Na2CO3 and Bi2O3 weighed in step S1 is slightly in excess by 1-5%.

[0014] Furthermore, step S1 is detailed as follows: S101: Place the raw material powder described in step S1 in an oven and dry it at 80~100℃ for 1~2 hours; S102: Weigh the dried raw material powder according to the stoichiometric ratio in the general formula and place it in the grinding jar. Add grinding media according to the mass ratio of powder:zirconium balls: anhydrous ethanol = 1: (1~5): (1~3). Mix the powder in a ball mill at a speed of 200~300 rpm for 6~18 hours to obtain a uniform slurry. S103: Separate the slurry and zirconium balls from step S102 and place them in an oven to dry at 80~120℃ for 3~6h until dry. After being processed through a 60~120 mesh sieve, place them in a muffle furnace and hold them at 800~950℃ for 2~6h to complete the pre-sintering treatment. The heating rate is 2~5℃ / min, and the cooling rate is natural cooling with the furnace. S104: Grind and crush the pre-fired powder obtained in step S103, and then perform secondary ball milling, drying and sieving according to the process in steps S102~103 to obtain NBST-BMZ ceramic powder.

[0015] Preferably, in step S2, the solvent is one or more of toluene, xylene, ethyl acetate, ethanol, and methyl ethyl ketone, and its content is 70-150% of the ceramic powder mass; the dispersant is one or more of tributyl phosphate, trioleic acid glyceride, and castor oil, and its content is 1-5% of the ceramic powder mass; the binder is polyvinyl butyral, and its content is 6-14% of the ceramic powder mass; the plasticizer is one or more of butyl benzyl phthalate, dibutyl phthalate, and polyethylene glycol, and its content is 3-8% of the ceramic powder mass; and the defoamer is one or more of dimethyl silicone oil and defoamer 716, and its content is 0-1% of the ceramic powder mass.

[0016] Furthermore, step S2 is detailed as follows: S201: The NBST-BMZ ceramic powder obtained in step S1 is initially mixed with solvent and dispersant by ball milling dispersion process. The dispersion medium is zirconium balls, the slurry: zirconium balls = 1: (1~3), the dispersion time is 4~12h, and the dispersion speed is 100~250rpm. S202: Add binder, plasticizer and defoamer to the primary slurry obtained in step S201 and continue ball milling according to the parameters described in step S201 to mix evenly.

[0017] S203: The uniform slurry obtained in step S202 is placed in a degassing device for vacuum stirring and degassing treatment for 5~30 minutes; S204: After degassing, the slurry is sealed and placed in a room temperature environment for 20~60 minutes for homogenization and reheating treatment. Then, the slurry is evenly coated onto the PET base tape using a casting machine or coating machine and dried to obtain NBST-BMZ thick film. S205: The NBST-BMZ thick film is cut to the required size and stacked, and then a multi-stage hot pressing process is used to produce a ceramic green body.

[0018] Preferably, the multi-stage hot pressing process in steps S2 and S205 is as follows: the hot pressing temperature is 50~80℃, the first stage hot pressing pressure is 10Mpa, the second stage hot pressing pressure is 20Mpa, the third stage hot pressing pressure is 30Mpa, the single-stage heat preservation and pressure holding time is 5~20min, and the hot pressing is naturally cooled to room temperature after completion.

[0019] Furthermore, step S3 is as follows: S301: The NBST-BMZ ceramic green body obtained in step S2 is placed directly on the zirconium plate and the binder is removed in a low-temperature muffle furnace using a multi-stage heating and cooling process. S302: The NBST-BMZ ceramic blank after debinding in step S301 is placed in a sealed alumina or zirconia crucible and sintered in a high-temperature muffle furnace using a multi-stage heating and cooling process.

[0020] Preferably, the multi-stage heating and cooling debinding process described in steps S3 and S301 is as follows: the first stage debinding process raises the temperature from room temperature to 180-200℃ at a heating rate of 0.5-3℃ / min and holds it for 60-120min; the second stage debinding process raises the temperature from 180-200℃ to 500-600℃ at a heating rate of 0.5-1.5℃ / min and holds it for 300-480min; the third stage debinding process lowers the temperature from 500-600℃ to 200-300℃ at a cooling rate of 1-2℃ / min, and then cools it to room temperature with the furnace.

[0021] Preferably, the multi-stage heating and cooling sintering process described in steps S3 and S302 is as follows: the first stage sintering process heats the temperature from room temperature to 800-950℃ at a heating rate of 5-8℃ / min and holds for 0 min; the second stage process heats the temperature from 800-950℃ to 1100-1180℃ at a heating rate of 2-5℃ / min and holds for 1-5 h; the third stage process cools the temperature from 1100-1180℃ to 800-950℃ at a cooling rate of 3-6℃ / min, and then the furnace is allowed to cool naturally to room temperature.

[0022] Through the above technical solution, the present invention achieves the following beneficial effects: 1. The general chemical formula proposed in this invention is (1-x)(Na) 0.3 Bi 0.38 Sr 0.28 TiO3)-xBi(Mg 0.5 Zr 0.5A lead-free relaxor ferroelectric energy storage ceramic material based on sodium bismuth titanate (B2O3), wherein 0 ≤ x ≤ 0.2, exhibits significant antiferroelectric-like properties and displays a slender waisted hysteresis loop with both high saturation polarization and extremely low remanent polarization; with the addition of bismuth complex ions Bi(Mg2+) 0.5 Zr 0.5 ) 6+ As the doping content increases, the waist of the hysteresis loop increases, resulting in a double hysteresis loop similar to that of an antiferroelectric material.

[0023] 2. This invention utilizes bismuth-containing complex ions Bi(Mg) 0.5 Zr 0.5 ) 6+ Doping refines the ceramic grains and increases the band gap, thereby effectively improving the breakdown electric field.

[0024] 3. This invention involves introducing Na... 0.3 Bi 0.38 Sr 0.28 Bi(Mg) doping in TiO3 relaxor ferroelectric matrix 0.5 Zr 0.5 ) 6+ By introducing ions with different valence states and radii, the local random field is enhanced, the anisotropic field is weakened, and the defect dipole pinning domain wall effect is induced. This enhances the relaxation characteristics and delays polarization saturation, promoting the transformation of the waisted hysteresis loop into a double hysteresis loop similar to an antiferroelectric.

[0025] 4. This invention employs a synergistic optimization strategy to multi-dimensionally regulate the structure of the ceramic material, ultimately achieving both high releasable energy storage density and efficiency. This addresses, to some extent, the problems of low energy storage density and energy density-efficiency mismatch in dielectric materials, providing a preparation method and material selection for developing environmentally friendly dielectric energy storage ceramic capacitors with both high energy storage density and efficiency. The energy storage density of the ceramic material can reach 2~5 J / cm³. 3 The energy storage efficiency can reach 80-95%; preferably x=0.15, the maximum releaseable energy storage density of this component is 5 J / cm³. 3 The energy storage efficiency is 90%.

[0026] 5. The preparation process of the sodium bismuth titanate-based lead-free relaxor ferroelectric energy storage ceramic material described in this invention adopts a multi-stage hot pressing process, which can reduce interlayer gas residue to a certain extent, reduce film delamination, cracking and flow during hot pressing, and improve material uniformity and density.

[0027] 6. The preparation process of the sodium bismuth titanate-based lead-free relaxor ferroelectric energy storage ceramic material described in this invention adopts a multi-stage debinding and sintering process, which can effectively remove organic substances such as binders, improve the density of ceramics, and avoid deformation and / or cracking of ceramic green bodies during high-temperature treatment.

[0028] 7. The sodium bismuth titanate-based lead-free relaxor ferroelectric energy storage ceramic material with antiferroelectric-like properties provided by the present invention does not contain toxic metals such as lead, is environmentally friendly and human-friendly, and can be widely used in various energy storage components. Attached Figure Description

[0029] Figure 1 Hysteresis loop diagrams of the ceramic materials prepared in Examples 1-4 of this invention under a breakdown electric field; Figure 2 The diagram shows the energy storage performance of the ceramic materials prepared in Examples 1-4 of this invention under a breakdown electric field. Detailed Implementation

[0030] The specific embodiments of the present invention will be described in detail below with reference to examples. It should be understood that the specific embodiments described herein are for illustration and explanation only and are not intended to limit the present invention. Example

[0031] (1) According to the chemical formula Na 0.3 Bi 0.38 Sr 0.28 Weigh the dried raw material powder according to the stoichiometric ratio of TiO3 and the ratio of Na2CO3 and Bi2O3 with a slight excess of 3%, and place it in a ball mill jar. Add grinding media according to the mass ratio of powder:zirconium balls: anhydrous ethanol = 1:4:2, and mix in a ball mill at 240 rpm for 12 hours to obtain a uniform slurry. Then, place the above slurry in an oven and dry it at 90°C for 5 hours. After grinding and passing it through a 60-mesh sieve, a primary mixed powder is obtained. The primary mixed powder is then placed in... Pre-sintering is performed in a muffle furnace at a heating rate of 3℃ / min, a holding temperature of 950℃, and a holding time of 2 hours, with cooling occurring during furnace operation. The pre-sintered powder is then obtained through crushing, grinding, and sieving through a 100-mesh sieve. The pre-sintered powder and grinding media are then subjected to a second ball milling process at a mass ratio of powder:zirconium balls: anhydrous ethanol = 1:4:2, at a speed of 240 rpm for 18 hours. The resulting slurry is then dried, ground, and sieved as described above to obtain Na. 0.3 Bi 0.38 Sr 0.28 TiO3 ceramic powder.

[0032] (2) Take 30g of Na 0.3 Bi 0.38 Sr 0.28TiO3 ceramic powder was ball-milled with 20g xylene, 20g anhydrous ethanol, and 1.5g trioleic acid glyceride, with a slurry-to-zirconium ball ratio of 1:3. The dispersion time was 12 hours and the dispersion speed was 200 rpm. Then, 3g polyvinyl butyral, 3g dibutyl phthalate, and 0.5g defoamer 716 were added, and mixing continued for 12 hours to obtain a casting slurry. The slurry was then subjected to vacuum stirring, degassing, homogenization, and reheating for a total of 40-60 minutes. The slurry was then uniformly coated onto a PET substrate using a casting machine or coating machine and dried to obtain a thick film. Finally, through cutting, lamination, and multi-stage hot pressing processes, Na... 0.3 Bi 0.38 Sr 0.28 TiO3 ceramic green body, wherein the hot pressing temperature is 50~80℃, the first hot pressing pressure is 10Mpa, the second hot pressing pressure is 20Mpa, the third hot pressing pressure is 30Mpa, the single-stage heat holding and pressure holding time is 5~20min, and after the hot pressing is completed, it is naturally cooled to room temperature.

[0033] (3) Put Na 0.3 Bi 0.38 Sr 0.28 TiO3 ceramic green bodies were placed on a zirconium plate and subjected to a multi-stage heating and cooling process in a low-temperature muffle furnace for binder removal. The first stage involved raising the temperature from room temperature to 180°C at a rate of 2°C / min and holding for 120 min. The second stage involved raising the temperature from 180°C to 500°C at a rate of 1°C / min and holding for 480 min. The third stage involved lowering the temperature from 500°C to 200°C at a rate of 2°C / min, followed by furnace cooling to room temperature. After debinding, the ceramic green body was placed in a sealed alumina crucible and sintered in a high-temperature muffle furnace using a multi-stage heating and cooling process. The first stage involved heating from room temperature to 800°C at a rate of 8°C / min and holding for 0 min. The second stage involved heating from 900°C to 1160°C at a rate of 4°C / min and holding for 3 h. The third stage involved cooling from 1160°C to 900°C at a rate of 6°C / min, followed by natural cooling to room temperature in the furnace to obtain the Na exhibiting antiferroelectric-like properties. 0.3 Bi 0.38 Sr 0.28 TiO3 lead-free relaxor ferroelectric energy storage ceramic material. Example

[0034] (1) According to the chemical formula 0.95 (Na 0.3 Bi 0.38 Sr 0.28 TiO3)-0.05Bi(Mg 0.5 Zr 0.5The stoichiometric ratio of O3 and the slight excess of Na2CO3 and Bi2O3 (2%) were used to weigh the dried raw material powder and place it in a ball mill jar. Grinding media were added according to the mass ratio of powder:zirconium balls: anhydrous ethanol = 1:4:3. The mixture was ball-milled at 280 rpm for 8 hours to obtain a uniform slurry. The slurry was then dried in an oven at 110°C for 3 hours. The dried, ground, and sieved powder was placed in a muffle furnace for pre-sintering treatment at a heating rate of 3°C / min, a holding temperature of 900°C, and a holding time of 3 hours. After cooling in the furnace, the powder was removed and subjected to crushing, grinding, and sieving through a 120-mesh sieve to obtain pre-sintered powder. The pre-sintered powder and grinding media were then ball-milled a second time at a mass ratio of powder:zirconium balls: anhydrous ethanol = 1:4:3 at 280 rpm for 12 hours. The slurry after the second ball milling was then processed according to the aforementioned drying, grinding, and sieving process to obtain 0.95 (Na2CO3:Bi2O3)0.95% of the raw material powder. 0.3 Bi 0.38 Sr 0.28 TiO3)-0.05Bi(Mg 0.5 Zr 0.5 O3 ceramic powder.

[0035] (2) Take 30g of 0.95 (Na) 0.3 Bi 0.38 Sr 0.28 TiO3)-0.05Bi(Mg 0.5 Zr 0.5 O3 ceramic powder was ball-milled with 15g toluene, 15g anhydrous ethanol, and 1.2g tributyl phosphate, with a slurry-to-zirconium ball ratio of 1:5. The dispersion time was 6 hours and the dispersion speed was 280 rpm. Then, 2.7g polyvinyl butyral, 1.5g dibutyl phthalate, 1.5g polyethylene glycol, and 0.5g methyl silicone oil were added and mixing continued for 10 hours to obtain a casting slurry. The slurry was then subjected to vacuum stirring, degassing, homogenization, and reheating for a total of 30-40 minutes. The slurry was then uniformly coated onto a PET substrate using a casting machine or coating machine and dried to obtain a thick film. Finally, a 0.95 (Na) ceramic film was obtained through cutting, lamination, and multi-stage hot pressing processes. 0.3 Bi 0.38 Sr 0.28 TiO3)-0.05Bi(Mg 0.5 Zr 0.5 O3 ceramic green body, in which the hot pressing temperature is 50~80℃, the first hot pressing pressure is 10Mpa, the second hot pressing pressure is 20Mpa, the third hot pressing pressure is 30Mpa, the single-stage heat holding and pressure holding time is 5~20min, and after the hot pressing is completed, it is naturally cooled to room temperature.

[0036] (3) Convert 0.95(Na 0.3 Bi 0.38 Sr0.28 TiO3)-0.05Bi(Mg 0.5 Zr 0.5 The O3 ceramic green body was placed on a zirconium plate and subjected to a multi-stage heating and cooling process in a low-temperature muffle furnace for binder removal. The first stage of binder removal involved raising the temperature from room temperature to 200°C at a rate of 1°C / min and holding for 90 minutes. The second stage involved raising the temperature from 200°C to 600°C at a rate of 1°C / min and holding for 300 minutes. The third stage involved lowering the temperature from 600°C to 300°C at a rate of 2°C / min, followed by furnace cooling to room temperature. The binder-removed ceramic green body was then... The ceramic blank was placed in a sealed alumina crucible and sintered in a high-temperature muffle furnace using a multi-stage heating and cooling process. The first stage involved heating from room temperature to 800°C at a rate of 6°C / min and holding for 0 min. The second stage involved heating from 900°C to 1150°C at a rate of 3°C / min and holding for 2.5 h. The third stage involved cooling from 1160°C to 900°C at a rate of 5°C / min, followed by natural cooling to room temperature in the furnace to obtain the 0.95(Na) ceramic blank exhibiting antiferroelectric-like properties. 0.3 Bi 0.38 Sr 0.28 TiO3)-0.05Bi(Mg 0.5 Zr 0.5 O3 lead-free relaxor ferroelectric energy storage ceramic material. Example

[0037] (1) According to the chemical formula 0.85 (Na 0.3 Bi 0.38 Sr 0.28 TiO3)-0.15Bi(Mg 0.5 Zr 0.5 Weigh the dried raw material powder according to the stoichiometric ratio of O3 and the ratio of slightly excess Na2CO3 (1.5%) and slightly excess Bi2O3 (3%), and place it in a ball mill jar. Add grinding media according to the mass ratio of powder:zirconium balls: anhydrous ethanol = 1:3:2, and mix in a ball mill at 260 rpm for 10 hours to obtain a uniform slurry. Then, place the slurry in an oven and dry it at 100°C for 4 hours. The dried, ground, and sieved mixed powder is then placed in a 60-mesh sieve. Pre-sintering was performed in a muffle furnace at a heating rate of 5℃ / min, a holding temperature of 880℃, and a holding time of 4h. After cooling in the furnace, the powder was removed and subjected to crushing, grinding, and sieving through a 100-mesh sieve to obtain pre-sintered powder. The pre-sintered powder and grinding media were then ball-milled a second time at a mass ratio of powder:zirconium balls: anhydrous ethanol = 1:3:2, at a speed of 300 rpm for 12h. The slurry after the second ball milling was then processed according to the aforementioned drying, grinding, and sieving process to obtain 0.85 (Na) 0.3 Bi 0.38 Sr0.28 TiO3)-0.15Bi(Mg 0.5 Zr 0.5 O3 ceramic powder.

[0038] (2) Take 30g of 0.85(Na) 0.3 Bi 0.38 Sr 0.28 TiO3)-0.15Bi(Mg 0.5 Zr 0.5 O3 ceramic powder was ball-milled with 10g toluene, 20g anhydrous ethanol, and 1.5g tributyl phosphate, with a slurry-to-zirconium ball ratio of 1:4. The dispersion time was 8 hours, and the dispersion speed was 240 rpm. Then, 2.85g polyvinyl butyral, 1.8g dibutyl phthalate, 1.8g polyethylene glycol, and 0.3g defoamer 716 were added and mixed until homogeneous to obtain a casting slurry. The slurry was then subjected to vacuum stirring, degassing, homogenization, and reheating for a total of 15-30 minutes. The slurry was then uniformly coated onto a PET substrate using a casting machine or coating machine and dried to obtain a thick film. Finally, a 0.95 (Na) ceramic film was obtained through cutting, lamination, and multi-stage hot pressing processes. 0.3 Bi 0.38 Sr 0.28 TiO3)-0.05Bi(Mg 0.5 Zr 0.5 O3 ceramic green body, in which the hot pressing temperature is 50~80℃, the first hot pressing pressure is 10Mpa, the second hot pressing pressure is 20Mpa, the third hot pressing pressure is 30Mpa, the single-stage heat holding and pressure holding time is 5~20min, and after the hot pressing is completed, it is naturally cooled to room temperature.

[0039] (3) Convert 0.85(Na 0.3 Bi 0.38 Sr 0.28 TiO3)-0.15Bi(Mg 0.5 Zr 0.5The O3 ceramic green body was placed on a zirconium plate and subjected to a multi-stage heating and cooling process in a low-temperature muffle furnace for binder removal. The first stage of binder removal involved raising the temperature from room temperature to 200°C at a rate of 1°C / min and holding for 90 minutes. The second stage involved raising the temperature from 200°C to 550°C at a rate of 0.5°C / min and holding for 420 minutes. The third stage involved lowering the temperature from 550°C to 300°C at a rate of 2°C / min, followed by furnace cooling to room temperature. The removed ceramic green body was then... The ceramic green body was placed in a sealed alumina crucible and sintered in a high-temperature muffle furnace using a multi-stage heating and cooling process. The first stage involved heating from room temperature to 800°C at a rate of 6°C / min and holding for 0 min. The second stage involved heating from 900°C to 1135°C at a rate of 3°C / min and holding for 3 h. The third stage involved cooling from 1135°C to 900°C at a rate of 5°C / min, followed by natural cooling to room temperature in the furnace to obtain the 0.85(Na) ceramic green body exhibiting antiferroelectric-like properties. 0.3 Bi 0.38 Sr 0.28 TiO3)-0.15Bi(Mg 0.5 Zr 0.5 O3 lead-free relaxor ferroelectric energy storage ceramic material. Example

[0040] (1) According to the chemical formula 0.80 (Na 0.3 Bi 0.38 Sr 0.28 TiO3)-0.20Bi(Mg 0.5 Zr 0.5 Weigh the dried raw material powder according to the stoichiometric ratio of O3 and the ratio of slightly excess Na2CO3 (2%) and slightly excess Bi2O3 (3%), and place it in a ball mill jar. Add grinding media according to the mass ratio of powder:zirconium balls: anhydrous ethanol = 1:3:2. Mix the powder in a ball mill at 280 rpm for 10 hours to obtain a uniform slurry. Then, place the slurry in an oven and dry it at 115°C for 3 hours. The dried, ground, and sieved mixed powder is then placed in a... Pre-sintering was carried out in a muffle furnace with a heating rate of 5℃ / min, a holding temperature of 850℃, and a holding time of 5h. After cooling in the furnace, the powder was removed and subjected to crushing, grinding, and sieving through a 100-mesh sieve to obtain pre-sintered powder. The pre-sintered powder and grinding media were then subjected to a second ball milling at a mass ratio of powder:zirconium balls: anhydrous ethanol = 1:3:2, at a speed of 300 rpm for 10h. The slurry after the second ball milling was then processed according to the aforementioned drying, grinding, and sieving process to obtain 0.80 (Na) 0.3 Bi 0.38 Sr 0.28 TiO3)-0.20Bi(Mg 0.5 Zr 0.5O3 ceramic powder.

[0041] (2) Take 30g of 0.80 (Na) 0.3 Bi 0.38 Sr 0.28 TiO3)-0.20Bi(Mg 0.5 Zr 0.5 O3 ceramic powder was ball-milled with 1,8-xylene, 12g anhydrous ethanol, and 1.2g trioleic acid glyceride, with a slurry-to-zirconium ball ratio of 1:4. The dispersion time was 8 hours, and the dispersion speed was 240 rpm. Then, 2.85g polyvinyl butyral, 1.5g dibutyl phthalate, 1.5g polyethylene glycol, and 0.3g defoamer 716 were added and mixed until homogeneous to obtain a casting slurry. The slurry was then subjected to vacuum stirring, degassing, homogenization, and reheating for a total of 15-30 minutes. The slurry was then uniformly coated onto a PET substrate using a casting machine or coating machine and dried to obtain a thick film. Finally, a 0.80 (Na) ceramic film was produced through cutting, lamination, and multi-stage hot pressing processes. 0.3 Bi 0.38 Sr 0.28 TiO3)-0.20Bi(Mg 0.5 Zr 0.5 O3 ceramic green body, in which the hot pressing temperature is 50~80℃, the first hot pressing pressure is 10Mpa, the second hot pressing pressure is 20Mpa, the third hot pressing pressure is 30Mpa, the single-stage heat holding and pressure holding time is 5~20min, and after the hot pressing is completed, it is naturally cooled to room temperature.

[0042] (3) Change 0.80(Na 0.3 Bi 0.38 Sr 0.28 TiO3)-0.20Bi(Mg 0.5 Zr 0.5)The green body of the O3 ceramic is placed on top of the zirconium plate and debinded in a low-temperature muffle furnace using a multi-stage heating and cooling process. In the first stage of the debinding process, the temperature is raised from room temperature to 200 °C at a heating rate of 0.5 °C / min and held for 90 min. In the second stage of the debinding process, the temperature is further raised from 200 °C to 550 °C at a heating rate of 0.5 °C / min and held for 420 min. In the third stage of the debinding process, the temperature is lowered from 550 °C to 300 °C at a cooling rate of 2 °C / min, and then cooled to room temperature in the furnace. After that, the debinded ceramic body is placed in a sealed alumina crucible and sintered in a high-temperature muffle furnace using a multi-stage heating and cooling process. In the first stage of the sintering process, the temperature is raised from room temperature to 800 °C at a heating rate of 8 °C / min and held for 0 min. In the second stage, the temperature is raised from 900 °C to 1120 °C at a heating rate of 3 °C / min and held for 2 h. In the third stage, the temperature is lowered from 1120 °C to 900 °C at a cooling rate of 5 °C / min, and then naturally cooled to room temperature in the furnace to obtain the 0.80(Na 0.3 Bi 0.38 Sr 0.28 TiO3)-0.20Bi(Mg 0.5 Zr 0.5 )O3 lead-free relaxor ferroelectric energy storage ceramic material.

[0043] The energy storage performance of the lead-free relaxor ferroelectric ceramics prepared in the above embodiments was analyzed, and the results are as Figures 1-2 shown.

[0044] Referring Figure 1 , that is, the hysteresis loop diagrams of the NBST-BMZ ceramic materials prepared in Examples 1 to 4 under the breakdown electric field, it can be found that: the ceramic materials prepared in each embodiment all exhibit extremely low hysteresis loss and antiferroelectric-like characteristics, and their hysteresis loops are slender waist-shaped and the waist degree increases significantly with the increase of the Bi(Mg 0.5 Zr 0.5 )O3 content. At the same time, the increase of the Bi(Mg 0.5 Zr 0.5 )O3 content significantly increases the breakdown electric field and delays the polarization saturation, which is beneficial to the improvement of the energy storage performance. When x = 0.15, corresponding to the ceramic material described in Example 3, its breakdown electric field can reach 340 kV / cm, and the maximum polarization obtained after delay can reach ~42 μC / cm 2 , and the difference between the maximum polarization and the remanent polarization can reach ~41 μC / cm 2 , laying a foundation for simultaneously achieving high recoverable energy storage density and efficiency.

[0045] Referring Figure 2 , that is, the energy storage performance diagrams of the NBST-BMZ ceramic materials prepared in Examples 1 to 4 under the breakdown electric field, it can be found by comparison that: Bi(Mg0.5 Zr 0.5 The increased O3 content significantly improved the energy storage performance of the ceramic material in the embodiments. Optimal energy storage performance was achieved when x = 0.15, corresponding to the ceramic material in Example 3, with a release energy density as high as 5 J / cm³. 3 It also boasts an energy storage efficiency of up to 90%. This invention addresses, to some extent, the problems of low energy storage density and mismatch between energy storage density and efficiency in dielectric materials, providing a preparation method and material selection for developing environmentally friendly dielectric energy storage ceramic capacitors that combine high energy storage density and efficiency.

[0046] The above embodiments are merely illustrative of the principles and effects of the present invention and are not intended to limit the invention. Any person skilled in the art can modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by those skilled in the art without departing from the spirit and technical concept disclosed in the present invention should still be covered by the claims of the present invention.

Claims

1. A lead-free relaxor ferroelectric energy storage ceramic material based on sodium bismuth titanate with antiferroelectric-like properties, characterized in that, The general formula for the composition of the ceramic material is: (1-x)(Na) 0.3 Bi 0.38 Sr 0.28 TiO3)-xBi(Mg 0.5 Zr 0.5 )O3, hereinafter abbreviated as NBST-BMZ, where 0≤x≤0.

2.

2. A sodium bismuth titanate-based lead-free relaxor ferroelectric energy storage ceramic material with antiferroelectric-like properties as described in claim 1, characterized in that, In the general formula for the composition of the above materials, x = 0.

15.

3. A method for preparing a sodium bismuth titanate-based lead-free relaxor ferroelectric energy storage ceramic material with antiferroelectric-like properties as described in claim 1, characterized in that, The steps include the following: S1: Na2CO3, Bi2O3, SrCO3, TiO2, MgO and ZrO2 with a purity of not less than 98% are selected as raw materials and weighed according to the stoichiometric ratio in the general formula of claim 1. NBST-BMZ ceramic powder is obtained through a process including ball milling, pre-sintering and crushing. S2: The NBST-BMZ ceramic powder obtained in step S1 is uniformly mixed with solvent, dispersant, binder, plasticizer and defoamer to obtain NBST-BMZ ceramic slurry. NBST-BMZ thick film is obtained by casting process, and NBST-BMZ ceramic green body is obtained by lamination and multi-stage hot pressing process. S3: The NBST-BMZ ceramic green body obtained in step S2 is subjected to multi-stage heating and cooling debinding and multi-stage heating and cooling sintering to obtain NBST-BMZ ceramic with antiferroelectric properties.

4. The preparation method according to claim 3, characterized in that, Step S1 specifically includes the following steps: S101: Place the raw material powders of Na2CO3, Bi2O3, SrCO3, TiO2, MgO, and ZrO2 in an oven and dry them at 80~100℃ for 1~2 hours; S102: Weigh the dried raw material powders according to the stoichiometric ratio corresponding to the general formula of claim 1, wherein Na2CO3 and Bi2O3 are added in excess of 1-5 mol% according to the theoretical stoichiometric amount; place the weighed raw material powders into a ball mill jar, add grinding media according to the mass ratio of powder:zirconium balls: anhydrous ethanol = 1: (1-5): (1-3), and ball mill at 200-300 rpm for 6-18 h to obtain a uniformly mixed slurry; S103: Separate the slurry and zirconium balls from step S102 and place them in an oven to dry at 80~120℃ for 3~6h until dry. After being processed through a 60~120 mesh sieve, place them in a muffle furnace and hold them at 800~950℃ for 2~6h to complete the pre-sintering treatment. The heating rate is 2~5℃ / min, and the cooling rate is natural cooling with the furnace. S104: Grind and crush the pre-fired powder obtained in step S103, and then perform secondary ball milling, drying and sieving according to the process in steps S102~103 to obtain NBST-BMZ ceramic powder.

5. The preparation method according to claim 3, characterized in that, The solvent in step S2 is one or more of toluene, xylene, ethyl acetate, ethanol, and methyl ethyl ketone, with a content of 70-150% of the ceramic powder mass; the dispersant is one or more of tributyl phosphate, trioleic acid glyceride, and castor oil, with a content of 1-5% of the ceramic powder mass; the binder is polyvinyl butyral, with a content of 5-15% of the ceramic powder mass; the plasticizer is one or more of butyl benzyl phthalate, dibutyl phthalate, and polyethylene glycol, with a content of 2-8% of the ceramic powder mass; and the defoamer is one or more of dimethyl silicone oil and defoamer 716, with a content of 0-1% of the ceramic powder mass.

6. The preparation method according to claim 3, characterized in that, Step S2 specifically includes the following steps: S201: The NBST-BMZ ceramic powder obtained in step S1 is initially mixed with solvent and dispersant by ball milling dispersion process. The dispersion medium is zirconium balls, the slurry: zirconium balls = 1: (1~3), the dispersion time is 4~12h, and the dispersion speed is 100~250rpm. S202: Add binder, plasticizer and defoamer to the primary slurry obtained in step S201 and continue ball milling according to the parameters described in step S201 to mix evenly; S203: The uniform slurry obtained in step S202 is placed in a degassing device for vacuum stirring and degassing treatment for 5~30 minutes; S204: After degassing, the slurry is sealed and placed in a room temperature environment for 20-60 minutes for homogenization and reheating treatment. Then, the slurry is evenly coated onto the PET base tape using a casting machine or coating machine and dried to obtain NBST-BMZ thick film. S205: The NBST-BMZ thick film is cut to the required size and stacked, and then a multi-stage hot pressing process is used to produce a ceramic green body.

7. The preparation method according to claim 6, characterized in that, The multi-stage hot pressing process described in step S205 is as follows: the hot pressing temperature is 50~80℃, the first stage hot pressing pressure is 10MPa, the second stage hot pressing pressure is 20MPa, the third stage hot pressing pressure is 30MPa, the single stage heat preservation and pressure holding time is 5~20min, and the hot pressing is naturally cooled to room temperature after completion.

8. The preparation method according to claim 3, characterized in that, Step S3 specifically includes the following steps: S301: The NBST-BMZ ceramic green body obtained in step S2 is placed directly on the zirconium plate and the binder is removed in a low-temperature muffle furnace using a multi-stage heating and cooling process. S302: The NBST-BMZ ceramic blank after debinding in step S301 is placed in a sealed alumina or zirconia crucible and sintered in a high-temperature muffle furnace using a multi-stage heating and cooling process.

9. The preparation method according to claim 8, characterized in that, The multi-stage heating and cooling process for removing adhesive described in step S301 is as follows: the first stage of the adhesive removal process raises the temperature from room temperature to 180-200℃ at a heating rate of 0.5-3℃ / min and holds it for 60-120min; the second stage of the adhesive removal process raises the temperature from 180-200℃ to 500-600℃ at a heating rate of 0.5-1.5℃ / min and holds it for 300-480min; the third stage of the adhesive removal process lowers the temperature from 500-600℃ to 200-300℃ at a cooling rate of 1-2℃ / min, and then cools it to room temperature with the furnace.

10. The preparation method according to claim 8, characterized in that, The multi-stage heating and cooling sintering process described in step S302 is as follows: the first stage sintering process raises the temperature from room temperature to 800-950℃ at a heating rate of 5-8℃ / min and holds for 0 min; the second stage process raises the temperature from 800-950℃ to 1100-1180℃ at a heating rate of 2-5℃ / min and holds for 1-5 h; the third stage process lowers the temperature from 1100-1180℃ to 800-950℃ at a cooling rate of 3-6℃ / min, and then the furnace is naturally cooled to room temperature.

Images