37 results about "Ferroelectric ceramics" patented technology

The invention discloses pure-phase bismuth ferrite-strontium titanate ceramic as well as a preparation method and application thereof, and belongs to the field of lead-free ferroelectric ceramic. Comprising the following steps: filling pure-phase BFO-STO precursor powder prepared by a hydrothermal method into a graphite mold, controlling the heating rate to a sintering temperature, and sintering under the conditions of external pressure and heat preservation, so as to finally prepare the BFO-STO ceramic. The BFO-STO ceramic is prepared through SPS sintering, volatilization of Bi < 3 + > and generation of impure phases are effectively inhibited, ferroelectric, dielectric and magnetic properties of the BFO ceramic are effectively improved, and possibility is provided for practical application of the BFO-STO ceramic in the fields of functional sensors, magnetic memories, piezoelectric generators, high-temperature inductors and the like.

The invention discloses a heat treatment method of high-polarization-intensity bismuth ferrite-lead titanate-barium zirconate titanate based ferroelectric ceramic, which comprises the following steps: arranging an electrode on the surface of a bismuth ferrite-lead titanate-barium zirconate titanate based ferroelectric ceramic sintered body, and then putting the sintered body into a rapid annealing furnace; the preparation method comprises the following steps: heating to 550-650 DEG C from room temperature at a heating rate of 5-80 DEG C / s, carrying out heat preservation for 45-75 seconds, carrying out first rapid annealing, and cooling to room temperature at a cooling rate of 250-350 DEG C / s, thereby obtaining the bismuth ferrite-lead titanate-barium zirconate titanate based ferroelectric ceramic. The heat treatment method provided by the invention can rearrange defects in the ceramic, increase domain conversion switches, improve the performance of the ceramic, and improve the performance of the ceramic. Furthermore, the ferroelectric piezoelectric property of the polarized BF-PT-BZT ceramic is greatly improved, and meanwhile, the polarized BF-PT-BZT ceramic has high Curie temperature.

The invention relates to the technical field of functional ceramic preparation, and particularly discloses a preparation method of an A-site doped PLZST-based anti-ferroelectric ceramic material, the chemical general formula of the anti-ferroelectric ceramic material is (Pb0.99-xLax) (Zr0. 6Sn0. 4) 0.9 Ta0. 02O3, the doping amount of A-site La is accurately limited in a range of 0.01 < = x < = 0.04, and multiple effects caused by La doping are effectively balanced. In the preferable range, the A-site vacancy generated by Laintroduction can be fully utilized to refine crystal grains and inhibit oxygen vacancy, so that the breakdown electric field intensity and insulativity of the material are remarkably improved, and the adverse effect of excessive doping on the saturation polarization intensity of the material is avoided. The coordination of high breakdown field strength, low hysteresis loss and high saturation polarization is realized, so that the obtained ceramic material has high energy storage density and high energy storage efficiency.

The application relates to the technical field of inorganic nonmetal functional ceramic materials, and discloses a polar vortex structure relaxor ferroelectric ceramic material and a preparation method and application thereof, the material is of a chemical formula (1-x)(0.7NaNbO3-0.3Sr 0.7 Bi 0.2 TiO3)-xCaSnO3, wherein 0<=x<=0.2, and a characteristic value is x=0.1. By adopting a step-by-step solid-phase reaction method, NaNbO3, Sr 0.7 Bi 0.2 TiO3 and CaSnO3 ceramic powders are pre-synthesized, then are ball-milled according to a stoichiometric ratio and are sintered into ceramics. The prepared ceramic material has a multi-phase coexistence, core-shell and polar vortex structure, and exhibits high saturation polarization intensity, low hysteresis, large breakdown field strength and excellent service stability, and has potential application in high-power pulse devices. The material is environment-friendly and simple in process, and is expected to provide a new technical path for design and preparation of high-performance and high-stability nonlinear dielectric energy storage materials.

The application relates to a structural health monitoring system and application thereof. A preparation method of a carbon fiber reinforced thermoplastic composite material involved in the system comprises the following steps: providing a plurality of carbon fiber reinforced thermoplastic resin layers; prepositioning a multifunctional sensor unit array between adjacent thermoplastic resin layers, the multifunctional sensor unit array comprising a functional film containing ferroelectric ceramic, an electrode layer, and an insulating protective layer between the functional film and the carbon fiber layer; wherein the functional film comprises ferroelectric ceramic material with dielectric and piezoelectric response characteristics; and performing selective laser solidification on the layer area prepositioned with the multifunctional sensor unit array, so that the layer interface locally melts under the action of laser heating and embeds the multifunctional sensor unit array between adjacent layers; wherein the peak temperature of the laser heating area in the selective laser solidification process is not higher than 200 DEG C.

The invention relates to the technical field of solid refrigeration materials, in particular to a barium titanate-based ferroelectric ceramic electrocaloric material and a preparation method thereof. The electrocaloric material is of a three-layer structure and sequentially comprises a first outer layer, a middle layer and a second outer layer, the first outer layer and the second outer layer are made of BZT-BST doped B2O3 ceramic materials, and the middle layer is made of BZT-BST doped MgO ceramic materials; through the sandwich structure design, the middle layer bears most voltage, and the overall breakdown field strength is remarkably improved. Due to the introduction of B2O3, the sintering temperature is reduced, and firm co-firing with a metal electrode is realized; by doping MgO, the insulating property of the middle layer is improved, and meanwhile, the ferroelectric property of the system is kept. The material can realize the electrocaloric temperature change of 2.05 K and the heat absorption capacity of 4.6 * 10 <-3 > J under the conditions of a 90kV / cm electric field and room temperature, has high pressure resistance, large refrigerating capacity and good reliability, and is suitable for the solid-state refrigeration field such as heat management of electronic devices.

The screening device for preparing the ferroelectric ceramics comprises a material barrel, a net barrel, a swinging mechanism and a driving mechanism are arranged in the material barrel, the swinging mechanism comprises a swinging rod and a springback assembly, the driving mechanism is used for driving the swinging rod and the net barrel to rotate, the net barrel screens materials through self rotation, and the springback assembly is used for driving the swinging rod to rotate reversely and reset. The swing rod knocks the net cylinder through forward and reverse rotation to trigger vibration, the swing rod comprises a rotating disc, a rocker arm and a pendulum bob, and the swing rod knocks the net cylinder through the pendulum bob. The motor is used for driving the mesh cylinder to rotate, meanwhile, the swing rod can be driven to rotate, materials can be screened through rotation of the mesh cylinder, the second cover shell can be hit through rotation of the swing rod to enable the mesh cylinder to vibrate, and therefore the materials can be prevented from blocking meshes in the mesh cylinder, and the material screening efficiency of the mesh cylinder is maintained.

The invention belongs to the field of ceramic materials, and particularly relates to a lead-free ferroelectric ceramic material and a preparation method thereof.The preparation method comprises the steps that aluminum nitrate nonahydrate and titanium isopropylate are dissolved in ethylene glycol and stirred, a citric acid solution is added, stirring continues, and a precursor solution A is prepared; dissolving bismuth nitrate pentahydrate in a citric acid solution, and stirring to prepare a precursor solution B; mixing the precursor solution A and the precursor solution B, stirring and drying to form gel; drying, grinding and crushing the gel, and calcining to obtain ceramic powder; the preparation method comprises the following steps: uniformly mixing ceramic powder and nano barium titanate powder by taking deionized water as a medium, and drying to obtain precursor powder; grinding and granulating the precursor powder and a 5wt% polyvinyl alcohol solution in an agate mortar, and then applying axial pressure to form a green body; and putting the green body into a corundum crucible with a cover, and sintering by using a two-step method to finally obtain the lead-free ferroelectric ceramic material. According to the invention, a universal combined optimization strategy is provided, and a strong relaxation ferroelectric system is developed.

This invention relates to the field of relaxor ferroelectric ceramic dielectric energy storage materials, specifically to a sodium bismuth titanate-based relaxor ferroelectric ceramic and its preparation method, wherein the chemical composition of the sodium bismuth titanate-based relaxor ferroelectric ceramic is (1-x)BNLT. ‑x BAN, of which BNLT is 0.9Bi 0.5 Na 0.5 TiO3-0.1Bi 0.5 Li 0.5 TiO3, BAN is BaAl 0.5 Nb 0.5 The value of O3 and x ranges from 0.06 to 0.18. When x = 0.15, the ceramic exhibits excellent performance with a recoverable energy storage density (Wrec) of not less than 14.0 J / cm³ and an energy storage efficiency (η) of not less than 84% under an electric field of 775 kV / cm. This invention employs a solid-state reaction sintering process, which is simple to prepare and low in cost, making it suitable for high-performance energy storage capacitors in pulsed power systems.

The invention discloses a sodium niobate-based ferroelectric ceramic and a preparation method thereof, and belongs to the field of dielectric ceramics. The chemical composition general formula of the sodium niobate-based ferroelectric ceramic is (Na < 0.874-0.874 x > Yb < 0.0085-0.0085 x > Tm < 0.0085-0.0085 x > Bi < 0.075-0.75 x > Ba < 0.5 a > Sr < 0.5 b >) (Nb < 0.85-0.85 x > Ti < 0.15-0.15 x > Sn < 0.5 c > Hf < 0.5 d >) O3, a = b = c = d, and x is greater than or equal to 2 and less than or equal to 6; the ceramic is of an ABO3 type perovskite structure, and in the ABO3 type perovskite structure, Bi ions are in a compound occupation form in which the A site and the B site coexist. The preparation method comprises the following steps: (1) proportioning and refining to obtain mixed powder; (2) performing pre-synthesis and powder treatment to obtain uniform powder; (3) preparing a molded green body; (4) removing organic matters; and (5) densifying and sintering to obtain the ferroelectric ceramic. The sodium niobate-based ferroelectric ceramic provided by the invention can achieve the effects of high Wrec, high eta, wide temperature range and excellent stability at the same time.

The invention belongs to the technical field of powder preparation by a wet chemical method, and provides a sodium bismuth titanate powder material and a preparation method thereof, the powder material is rhombohedral phase (Bi0. 5Na0. 5) TiO3, the particle morphology of the powder material is a nanocube, and the average size is 76nm. The (Bi0. 5Na0. 5) TiO3 nanocube is prepared through a two-step heating hydrothermal method, has the advantages of being simple in process, low in cost, good in stability and repeatability, capable of being produced on a large scale and the like, and has wide application prospects in the fields of sodium bismuth titanate, sodium bismuth titanate-based ferroelectric ceramics, barium titanate-based thermal sensitive ceramics and the like. The (Bi0. 5Na0. 5) TiO3 nanocube powder prepared by the invention is used as a raw material, (Bi0. 5Na0. 5) TiO3 ceramic sintered at 1100 DEG C for 4 hours has good sinterability and ferroelectricity, the relative density of the (Bi0. 5Na0. 5) TiO3 ceramic is 95% or above, and the maximum polarization intensity, the remanent polarization intensity and the coercive field of the (Bi0. 5Na0. 5) TiO3 ceramic are 40.02 mu C / cm < 2 >, 27.78 mu C / cm < 2 > and 87.5 kV / cm respectively.

The invention belongs to the field of solid electrolyte materials, and provides a PVDF-BST ceramic nanofiber composite solid electrolyte and a preparation method thereof.The PVDF-BST ceramic nanofiber composite solid electrolyte comprises a polyvinylidene fluoride (PVDF) polymer matrix and Ba0. 6Sr0. 4TiO3 (BST) ceramic nanofibers evenly dispersed in the matrix; the BST ceramic nanofiber is a ferroelectric ceramic fiber with a perovskite structure, the diameter of the BST ceramic nanofiber is 200-500nm, the filling proportion of the BST ceramic nanofiber is 2-10wt%, the PVDF matrix contains one or more lithium salts of LiClO4, LiPF6 or LiTFSI, and the thickness of the composite film is 50-100mu m; in the invention, the ionic conductivity is high, the interface stability is good, the material can be used for an all-solid-state lithium ion battery, the cycle performance and safety of the battery are obviously improved, and the preparation process is beneficial to industrialization.

The invention discloses pure-phase bismuth ferrite ceramic as well as a preparation method and application thereof, and belongs to the field of lead-free ferroelectric ceramic. Comprising the following steps: putting pure-phase bismuth ferrite precursor powder prepared by a hydrothermal method into a graphite mold, controlling the heating rate, heating to a sintering temperature, applying pressure, keeping the temperature, sintering, and finally preparing the pure-phase bismuth ferrite ceramic. According to the pure-phase bismuth ferrite ceramic prepared through SPS sintering, volatilization of Bi < 3 + > and generation of impure phases are effectively inhibited. The bismuth ferrite ceramic shows good magnetic performance, the magnetic performance is enhanced, good dielectric stability is shown, and the bismuth ferrite ceramic has certain ferroelectricity and good energy storage performance. Aiming at the problems that pure-phase bismuth ferrite ceramic is difficult to prepare by a traditional solid-phase reaction method, a mixed phase is generated due to Bi < 3 + > volatilization and oxygen vacancy defects caused by high-temperature sintering, multiferroic performance is unstable and the like, the preparation process of the bismuth ferrite ceramic is optimized by adopting a mode of combining a hydrothermal method and spark plasma sintering (SPS).

The application discloses a ferroelectric ceramic material with synergic light transmittance and ferroelectricity and a preparation method thereof, and belongs to the technical field of ceramic materials. 0.48 Na 0.52 )NbO3- x LaF3, x represents the mole number of LaF3, x is 0.01-0.04; the ceramic material is uniformly distributed with nanoscale polar microzones PNRs, and the polar microzones PNRs are easily flipped under an external electric field. By introducing LaF3 as a composite dopant, the synergic effect of the rare earth cation La 3+ and the anion F ‑ is utilized to realize nanosizing and efficient regulation of the KNN ceramic ferroelectric domain structure, so that the optical transmittance of the ceramic material is significantly improved under the premise of maintaining good ferroelectricity, and the process is simple and suitable for industrialization.

The present application relates to the technical field of material, and discloses a method for enhancing the electrostriction of sodium bismuth titanate-based relaxor ferroelectric.The present application induces the original large-size non-percolating polar region in the percolating sodium bismuth titanate-based relaxor by pre-polarizing the sodium bismuth titanate-based relaxor ferroelectric ceramic near the critical position synthesized by the traditional solid-phase method, reduces the nucleation barrier in the field-induced strain process, and significantly enhances the electrostriction effect.The sodium bismuth titanate-based relaxor ferroelectric ceramic of the present application has obviously improved electrostriction under the excitation of 60 kV / cm electric field compared with the initial state, and has more excellent performance than the ordinary sodium bismuth titanate-based relaxor ferroelectric ceramic.

The invention relates to the technical field of inorganic nonmetal functional ceramic materials, and discloses a dislocation-induced polar vortex structure relaxor ferroelectric ceramic material as well as a preparation method and application thereof, the chemical formula of the material is (1-x) Ba < 0.5 > Bi < 0.5 > Ti < 0.5 > Fe < 0.5 > O < 3-x > Ca < 0.7 > La < 0.2 > ZrO < 3 >, x is greater than or equal to 0 and less than or equal to 0.2, and the characteristic value is x = 0.1. The preparation method comprises the following steps: synthesizing Ba0. 5Bi0. 5Ti0. 5Fe0. 5O3 and Ca0. 7La0. 2ZrO3 ceramic powder in advance by adopting a step-by-step solid-phase reaction method, carrying out ball-milling mixing according to a stoichiometric ratio, and sintering to obtain the ceramic. The prepared ceramic material has two-phase coexistence, high-concentration double-charge oxygen vacancies, dislocation lines penetrating through a core-shell layer and a polar vortex structure, shows high saturation polarization intensity, low hysteresis, large breakdown field strength and excellent service stability, and has potential application in high-power pulse devices.

The invention belongs to the technical field of electronic ceramics, and particularly discloses a low-Curie-temperature medium-entropy lead magnesium tungstate-based ceramic and a preparation method and application thereof, the chemical general formula of the low-Curie-temperature medium-entropy lead magnesium tungstate-based ceramic is Pb (Mg < 1 / 4 > W < 1 / 4 > B '< 1 / 4 > B' < 1 / 4 >) O3, B '= Yb < 3 + > or Lu < 3 + >; b ''= Nb < 5 + > or Ta < 5 + >. According to the low-Curie-temperature medium-entropy lead magnesium tungstate-based ceramic and the preparation method and application thereof, the Curie temperature TC of the lead magnesium tungstate ceramic can be effectively reduced through the method, the dielectric constant is increased, low dielectric loss is kept, and the obtained ceramic has a pure perovskite structure and good compactness; the phase change temperature of the lead magnesium tungstate-based antiferroelectric ceramic ranges from-11 DEG C to-24 DEG C, the maximum relative dielectric constant ranges from 800 to 1100, the maximum dielectric loss tan delta ranges from 0.05 to 0.065, and the problems that an existing lead magnesium tungstate-based antiferroelectric ceramic is high in phase change temperature and low in dielectric constant can be solved.

The invention relates to the technical field of ceramics, in particular to an anti-reduction two-phase ferroelectric energy storage ceramic as well as a preparation method and application thereof. The general structural formula of the ceramic is PbaLabZrcTidOe + xwt% Y2O3, wherein a is equal to 0.5 to 1.5, b is equal to 0.01 to 0.1, c is equal to 0.5 to 1.5, d is equal to 0.005 to 0.05, and e is equal to 1.6 to 4.7; 0 lt; xlt; 8. Y2O3 with a specific content is added, so that the stability of a ceramic antiferroelectric phase is improved, the dispersion relaxation of a ceramic material is promoted, the breakdown electric field of the antiferroelectric ceramic is improved, and the reduction resistance of the ceramic is also improved; by matching with a specific tape casting process, the energy storage density of the prepared ceramic is 10-12J / cm < 3 >, and the energy storage efficiency is greater than 80%; the material can be used for an energy storage capacitor and has a good application prospect in a pulse power system.

The invention relates to the technical field of ferroelectric ceramic manufacturing, in particular to a calcium bismuth titanate based ferroelectric ceramic material and a preparation method and application thereof. The chemical formula of the calcium bismuth titanate-based ferroelectric ceramic material is CaBi4-xRxTi4O15-yMnO2, R is one or more of lanthanide rare earth elements, in the formula, x is more than 0 and less than or equal to 0.2, and y is more than or equal to 0.1 wt% and less than or equal to 0.5 wt%. The calcium bismuth titanate-based ferroelectric ceramic material disclosed by the invention has the original ferroelectric, piezoelectric and dielectric properties, also has a photoluminescence characteristic, and belongs to a novel multifunctional material. The ceramic material has excellent photoelectric properties, and has wide application prospects in the fields of photoelectric integration, micro electro mechanical system, photoelectric sensing, LED technology and the like.

The invention relates to bismuth titanate-based lead-free antiferroelectric ceramic as well as a preparation method and application thereof. The chemical composition of the bismuth titanate-based lead-free antiferroelectric ceramic is Bi (4-x) PrxTi3O12, wherein x is greater than or equal to 1.2 and less than or equal to 1.4. The bismuth titanate-based lead-free antiferroelectric ceramic is successfully designed based on typical three-layer bismuth titanate ceramic by introducing a specific amount of Pr element to induce oxygen octahedron rotation, and has the characteristics of antiferroelectric characteristic, high breakdown field strength, high energy storage density and high efficiency. The bismuth titanate-based lead-free antiferroelectric ceramic has relatively high energy storage application potential, the recoverable energy density is 8.0 to 11.97 J / cm < 3 >, the energy storage efficiency is 75.0 to 87.0 percent, and the breakdown electric field is 898 to 1058 kV / cm.

Power generation system, comprising: a ceramic element comprising a ferroelectric ceramic with a Curie temperature of 90 °C or less; and a current extraction device for extracting current from the ceramic element, where The ferroelectric ceramic exhibits a space charge polarization, and The power generation system generates electricity by applying a temporal temperature change beyond the Curie temperature to the ferroelectric ceramic.

The invention discloses a ferroelectric ceramic-based negative capacitance structure and a preparation method thereof, and belongs to the field of functional material application, and the construction of uneven distribution of defects is realized in ferroelectric ceramic through proper material treatment, so that the distribution of spontaneous polarization in the ceramic can be correspondingly changed. And under the influence of defect distribution, adjacent ferroelectric layers with large spontaneous polarization intensity difference can be formed at proper positions in the ceramic body, and under the condition that spontaneous polarization cannot be completely compensated, the negative capacitance characteristic can be shown.

The invention relates to an out-of-plane / in-plane differential response flexible sensing material and a preparation method thereof, and belongs to the field of flexible sensing materials. The chemical formula of the flexible sensing material is xAg / PDMS, the numerical value of x is 0-60 vol% and is not 0, x is the volume ratio of Ag to PDMS, the particle size range of Ag nanoparticles is 0.01-20 [mu] m, the functional auxiliary material of the flexible sensing material is a perovskite structure ferroelectric ceramic material (BCZT), and the volume ratio of Ag to BCZT is 3: 100. According to the flexible sensing material, silver nanoparticles and PDMS are compounded, and the silver nanoparticles are regulated by means of an external electric field to form Ag nanoparticle columns which are aggregated in the out-of-plane direction and are isolated from one another, so that the Ag nanoparticles are arranged in a chain shape in the out-of-plane direction, and differential response of high out-of-plane sensitivity / insensitive in-plane sensitivity is achieved; the construction of a quasi-conductive network is realized under the condition of low filling amount, meanwhile, good mechanical flexibility of the material is maintained, and the specific types and geometrical shapes of the conductive particles can be flexibly selected according to actual requirements.

This invention relates to the field of dielectric energy storage ceramic materials, specifically to a CaTiO3-based relaxor ferroelectric ceramic material and its preparation method. The general chemical formula of the CaTiO3-based composite relaxor ferroelectric ceramic material is: (1-x)Ca 0.5 Bi 0.25 Na 0.25 TiO3-xBaZrO3, where 0 < x ≤ 0.30, is produced by solid-state reaction method, in which Bi2O3, Na2CO3, CaCO3, TiO2, BaCO3, and ZrO2 are stoichiometrically proportioned, followed by wet ball milling, pre-calcination, granulation, tableting, debinding, and sintering. This invention, by constructing a relaxor ferroelectric heterojunction, synergistically optimizes the breakdown field strength, polarization intensity, and dielectric loss, solving the problems of polarization saturation and low energy storage efficiency in traditional ferroelectrics.

The invention relates to a lead-free dielectric energy storage ceramic material with a self-assembled multiphase core-shell structure and a preparation method thereof, and the preparation method comprises the following steps: taking ceramic raw materials according to the stoichiometric ratio of (1-x) [(1-y) Ba (Zr0. 1Ti0. 9) O3-yBi (Zn2 / 3Ta1 / 3) O3]-x (Bi0. 5Na0. 5) TiO3, and uniformly mixing to obtain a mixed raw material; carrying out pre-sintering, secondary ball-milling mixing, drying, sieving, granulating, pre-pressing molding and cold isostatic pressing on the mixed raw materials to prepare a ceramic green body; and sintering and cooling the ceramic green body to obtain the lead-free dielectric energy storage ceramic material. A proper amount of sodium bismuth titanate elements are subjected to solid solution in a lead-free ferroelectric ceramic material matrix, and after burdening and high-temperature sintering, a core-shell microstructure is spontaneously formed in ceramic crystal grains, so that the obtained lead-free dielectric energy storage ceramic material has high energy storage density, high breakdown electric field and high polarization intensity, and meanwhile, the process is simple, and the cost is low.

The invention provides an antibacterial toothpaste, comprising a charged antibacterial toothpaste abrasive. The charged antibacterial toothpaste abrasive comprises a ferroelectric ceramic. The ferroelectric ceramic is selected from at least one or a compound or a composition of more than one of potassium sodium niobate, i.e. K0.5Na0.5NbO3, barium titanate, i.e. BaTiO3, lithium niobate, i.e. LiNbO3, and barium strontium titanate, i.e. BaxSr1−xTiO3, where 0<x<1. In the inventive antibacterial toothpaste, the charged antibacterial toothpaste abrasive can maintain good electrical stability, such that an antibacterial toothpaste containing same can play a lasting antibacterial role by utilizing a polarization effect, and has a relatively good antibacterial performance, thereby achieving both teeth cleaning and antibacterial effects.

The invention relates to a pyroelectric pulse power generation method. The pyroelectric pulse power generation method comprises the following steps: (1) connecting polarized ferroelectric ceramic with a phase change temperature of T0 into a circuit loop which contains a switch and is in an open circuit state; (2) stabilizing the polarized ferroelectric ceramic at a phase transition temperature T1 or below; (3) enabling the ferroelectric ceramic stabilized below the phase change temperature T1 to be in contact with a heat sink of which the temperature is T2 and is greater than T0, and enabling the temperature of the ferroelectric ceramic to be rapidly increased to the temperature T2 which is greater than T0; and (4) performing short-circuit discharge on a circuit loop where the ferroelectric ceramic is located, outputting pulse voltage and pulse current, and completing generation of pyroelectric pulse power.

The application relates to the field of antiferroelectric ceramic materials and discloses a lead-free antiferroelectric ceramic, a preparation method and application thereof. The chemical composition of the ceramic is (1-x-y)NaNbO3-xABO3-yLa2O3-zMnO2, wherein A is one of Ca, Sr and Ba, B is one of Hf, Zr, Sn and Ti, 0.1<=x<=0.2, 0.05<=y<=0.1 and 0.01<=z<=0.03. The ceramic is a sodium niobate-based antiferroelectric ceramic. The capacitance density of the ceramic increases with the increase of an applied electric field intensity (0-20 kV / mm). The maximum capacitance density change amplitude of a pulse capacitor element made of the ceramic is less than 8% with the increase of working temperature under alternating-current and direct-current coupling electric field (alternating-current electric field 8-10 kV / mm and direct-current electric field 18-20 kV / mm), and the temperature stability of the lead-free antiferroelectric ceramic is significantly increased.

The application relates to the technical field of electronic functional materials and devices, and relates to a sodium bismuth titanate-based relaxor ferroelectric ceramic material with a composition gradient structure and a preparation method. 0.47 Na 0.47 Ba 0.06 Ti 1‑x (Li 1 / 4 Nb 3 / 4 ) x O3, and the preparation method comprises the following steps: according to the chemical formula, mixing raw materials, and sequentially performing a first ball milling, discharging, drying, pre-sintering, a second ball milling, discharging, drying, roller milling, flow casting, laminating and pressing, degassing and sintering processes to obtain the ceramic material. Compared with the prior art, the material provided by the application is a multilayer composite lead-free material, the ceramic has a novel design structure, the high electrocaloric effect in a wide temperature range is excellent, has great application prospects in the field of novel solid-state refrigeration technology, is not easy to pollute and damage the environment, has low preparation cost, good stability and the like.

The invention provides a positive electrode material, a preparation method of the positive electrode material, a secondary battery and an electric device. The positive electrode material comprises an inner core and a coating material, the inner core comprises a nickel-containing lithium transition metal oxide, and the coating material comprises a ferroelectric ceramic material and a fast ion conductor material. The preparation method of the positive electrode material comprises the steps that nickel-containing lithium transition metal oxide and a coating material are mixed and then calcined in the oxygen atmosphere, the positive electrode material is obtained, and the coating material comprises a ferroelectric ceramic material and a fast ion conductor material. The two coating materials construct a double-coating structure on the surface of the inner core, the active ion kinetics at the positive electrode is improved through a synergistic effect, the discharge rate of the secondary battery is improved, and the positive electrode material is effectively protected, so that the cycle performance is optimized.