102 results about "Bismuth ferrite" patented technology

The invention discloses a method for preparing a bismuth ferrite composite catalytic material by using red mud as well as a product and application of the bismuth ferrite composite catalytic material. The method comprises the following steps: mixing chlorine salt and red mud, uniformly stirring, adding a hydrochloric acid solution, uniformly stirring, roasting, recovering flue gas generated in the roasting process, and obtaining roasting residues and roasting dust generated by recovering the flue gas after roasting is finished; and mixing the roasted dust and bismuth nitrate, uniformly stirring, adding the calcined residue, uniformly grinding, adding water, stirring, drying the material, and calcining to obtain the bismuth ferrite composite catalytic material. The preparation process is simple, the red mud is used as a main raw material, and full-amount resource utilization of the red mud can be achieved. The prepared composite catalytic material can be used for efficiently purifying landfill leachate, and COD, ammonia nitrogen, total phosphorus and heavy metal pollution are efficiently removed through a photocatalysis mechanism.

The invention provides an anti-ferroelectric lanthanum ferrite, bismuth ferrite and strontium titanate superlattice film with high energy storage density as well as a preparation method and application thereof. The anti-ferroelectric lanthanum ferrite, bismuth ferrite and strontium titanate superlattice film with high energy storage density comprises a substrate layer, a bottom electrode layer and a plurality of stacked relaxation ferroelectric layers, wherein the bottom electrode layer and the multiple stacked relaxation ferroelectric layers are sequentially arranged on the substrate layer; each relaxor ferroelectric layer sequentially comprises a first functional layer, a second functional layer and a third functional layer from bottom to top; the first functional layer comprises LaFeO3, the second functional layer comprises BiFeO3, and the third functional layer comprises SrTiO3. The anti-ferroelectric lanthanum ferrite, bismuth ferrite and strontium titanate superlattice thin film with the high energy storage density has small electric leakage performance and high polarization value, and more excellent energy storage performance is achieved.

The invention relates to the technical field of piezoelectric ceramics, in particular to a bismuth ferrite-lead titanate-zinc bismuth titanate ternary system piezoelectric ceramic material as well as preparation and application thereof. The chemical general formula of the bismuth ferrite-lead titanate-zinc bismuth titanate ternary system piezoelectric ceramic material disclosed by the invention is (1-x-y) BiFeO3-x (PbMez) TiO3-yBi (Zn0. 5Ti0. 5) O3, wherein Me is an alkaline earth metal element, x is equal to 0.4-0.8, y is equal to 0.05-0.3, z is equal to 0.05-0.5, and 1-x-y is greater than 0. The piezoelectric ceramic material has large anisotropy (d33 / d31 is between 5 and 60) and relatively high voltage (d33 is greater than 100pC / N), has a wide application prospect in the technical field of high-frequency image sonar transducers, and solves the problems of low piezoelectric coefficient and piezoelectric anisotropy of the existing bismuth ferrite-lead titanate-zinc bismuth titanate ternary system piezoelectric ceramic material.

The invention discloses a bismuth ferrite-based ceramic material with low energy consumption and high energy storage and a low-temperature rapid sintering preparation method of the bismuth ferrite-based ceramic material, a flash sintering technology is applied to 0.55 BiFeO3-0. 4SrTiO3-0.05 NaNbO3 (BFST-0. 05NN) ceramic, on one hand, the component of 0.6 BiFeO3-0. 4SrTiO3 is close to a morphotropic phase boundary (MPB) to provide high polarization, and the introduction of NaNbO3 improves the structure disorder and promotes the relaxation behavior, so that the energy storage efficiency is improved; on the other hand, by optimizing the electric field (100-250 V / cm) and the flash sintering time under the fixed current density (40 mA / mm < 2 >), reactive densification can be achieved at the very low temperature and within the ultra-short time, and compared with traditional solid sintering, the furnace temperature is reduced by nearly 500 DEG C; flash sintering can realize densification of the ceramic, inhibit grain growth of the ceramic, refine a grain structure, inhibit volatilization of volatile elements and inhibit leakage conductance current at the same time, the lead-free bismuth ferrite-based ceramic with high breakdown and high energy storage and excellent ferroelectric, piezoelectric and energy storage performance is obtained, and green development and high energy storage are realized at the same time.

The invention provides a bismuth ferrite-graphite phase carbon nitride photocatalyst and a preparation method and application thereof, and relates to the technical field of photocatalysis, the preparation method comprises the following steps: dissolving a bismuth source and an iron source in a solvent, mixing with a mineralizing agent, and carrying out a hydrothermal synthesis reaction to obtain bismuth ferrite; performing first roasting treatment on the nitrogen-containing organic matter precursor to obtain graphite-phase carbon nitride; and mixing bismuth ferrite and graphite phase carbon nitride, and carrying out grinding treatment and second roasting treatment to obtain the bismuth ferrite-graphite phase carbon nitride photocatalyst. According to the preparation method, bismuth ferrite and graphite-phase carbon nitride which are prepared respectively are compounded, a Z-type heterojunction can be constructed at an interface of the bismuth ferrite and the graphite-phase carbon nitride, an internal electric field is formed, so that photo-induced electrons and holes are efficiently separated, compounding of the photo-induced electrons and the holes is effectively inhibited, and finally the oxidation-reduction capacity of the material is remarkably enhanced; therefore, the photocatalyst shows excellent photocatalytic performance, high selectivity and good cycle stability.

The invention relates to the technical field of environmental governance, and particularly discloses a bismuth ferrite-based photo-Fenton catalyst and application thereof. The bismuth ferrite-based photo-Fenton catalyst comprises a bismuth ferrite matrix or a catalyst, the bismuth ferrite matrix comprises Fe (NO) 9HO and Bi (NO) 5HO in a molar ratio of 1: 1-1: 1.1, the catalyst is one of metal-doped bismuth ferrite, non-metal-doped bismuth ferrite or a bismuth ferrite composite material, and the loading amount of metal in the metal-doped bismuth ferrite is 0.5-5 wt%. Fe (NO) 9HO and Bi (NO) 5HO are adopted as precursors, the stoichiometric ratio of a bismuth ferrite matrix can be regulated and controlled, generation of impurity phases is inhibited, and it is ensured that the matrix has a complete perovskite structure and a good photoresponse characteristic; meanwhile, modification means such as metal doping, non-metal doping or composite carrier loading are adopted.

The application discloses a magnetoelectric heterojunction film and a preparation method thereof. The magnetoelectric heterojunction film comprises a strontium titanate base layer, a strontium ruthenate electrode layer, a bismuth ferrite ferroelectric material layer and a SmCo-based ferromagnetic material layer which are stacked in sequence. The magnetoelectric heterojunction film has the multi-ferroelectric layer room-temperature magnetoelectric coupling effect and the excellent magnetic performance of the ferromagnetic layer, and the magnetoelectric coupling effect of the heterojunction film can be enhanced through the strong exchange bias effect at the interface.

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 application discloses a kind of bismuth ferrite-barium titanate textured piezoelectric ceramics and preparation method thereof, belong to ceramic preparation technical field, the preparation method includes: with (001) crystal direction BaTiO3 flaky microcrystal as template, with (1-x) BiFeO3-xBaTiO3 ceramic matrix powder is mixed, through casting process, matrix powder is grown along the template crystal direction, during, by controlling the amount of BaTiO3 flaky microcrystal, so that the volume ratio of it and ceramic matrix powder does not exceed 0.06, the thickness of casting film is 30~50 μm, and high-temperature sintering and high-temperature quenching mode with temperature up to 970 ℃~1040 ℃ is used, finally form textured BF-BT ceramic, the formed ceramic has good piezoelectric property and texture degree, and the above method process is simple, without adding additional material.

This invention relates to the field of wastewater treatment technology, specifically to a metal-doped bismuth ferrite-based perovskite composite material, its preparation method, and its applications. The molecular formula of the metal-doped bismuth ferrite-based perovskite composite material is Bi. 1‑x A x Fe 1‑y B y O3; 0 ≤ x < 1, 0

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.

Disclosed herein is a battery (e.g., a Li-ion battery) comprising: an anode comprising bismuth ferrite and a binder; a cathode; and an electrolyte comprising a lithium compound and a fluoroethylene carbonate (FEC) additive. Batteries with a bismuth ferrite anode having a carboxymethyl cellulose (CMC) binder and a lithium-containing electrolyte with FEC additive, show a capacity of up to 750 mAh / g at 100 mA / g and high capacity retention, with over 400 mAh / g at 500 mA / g after 1,000 cycles.

The application provides a BiFeO3-graphitic carbon nitride photocatalyst and a preparation method and application thereof, relates to the field of photocatalysis technology, and the preparation method comprises the following steps: dissolving a bismuth source and an iron source in a solvent, mixing with a mineralizer, and performing a hydrothermal synthesis reaction to obtain BiFeO3; performing first calcination treatment on a nitrogen-containing organic precursor to obtain graphitic carbon nitride; and performing grinding treatment and second calcination treatment on the mixture of BiFeO3 and graphitic carbon nitride to obtain the BiFeO3-graphitic carbon nitride photocatalyst. The preparation method can construct a Z-type heterojunction at the interface of the separately prepared BiFeO3 and graphitic carbon nitride, form an internal electric field, efficiently separate photo-generated electrons and holes, effectively inhibit the recombination of the photo-generated electrons and holes, finally significantly enhance the redox capacity of the material, and make the material exhibit excellent photocatalytic performance, high selectivity and good cycle stability.

The present invention provides a strontium titanate-based oxide superlattice thin film memristor and a preparation method thereof. The preparation method comprises the following steps: using a niobium-doped strontium titanate single crystal substrate as a bottom electrode; alternately depositing strontium titanate layers and another type of oxide film layer on the surface of the niobium-doped strontium titanate single crystal substrate to prepare a strontium titanate-based oxide superlattice thin film as a storage dielectric layer, wherein the other type of oxide film layer is selected from one of yttrium-doped zirconium oxide, lanthanum cobalt oxide, or bismuth ferrite; and further depositing a metal film as a top electrode on the surface of the substrate coated with the storage dielectric layer obtained in step S2, to obtain a memristor comprising bottom electrode||STO-based oxide superlattice thin film storage dielectric layer||top electrode. The strontium titanate-based oxide superlattice thin film memristor prepared by this preparation method can form a single crystal or a superlattice thin film with high crystal integrity, and the memristor has a low operating voltage and high configuration stability.

The invention discloses a texture preparation method for high-performance lead-free piezoelectric ceramics of bismuth ferrite-barium titanate. The general formula of the ceramic composition is as follows, where the molar fraction ratio of BiFeO3 and BaTiO3 is 2:1, x, y, t, and m all represent molar fractions, and 0 < x ≤ 0.05, 0 < y ≤ 0.05, 0 < t ≤ 0.05, 0 < m ≤ 0.05. In the sintering stage of the invention, a temperature gradient field is constructed to make the ceramic grains grow texture-directionally, and a textured piezoelectric ceramic with a piezoelectric constant d 33 reaching above 1000 pC / N at 350 °C and a T dr reaching above 350 °C is obtained. The preparation process of the invention is simple, and the prepared ceramic has excellent high-temperature performance and can be applied to the field of high-temperature piezoelectricity.

The application discloses a method for preparing a high self-polarization piezoelectric performance bismuth ferrite-based film through multi-element isometric solid solution. The method comprises the following steps: configuring sols of more than three different cations which are solid-solved at B positions of bismuth ferrite, then dropping the sols on a substrate, uniformly coating the sols, solidifying, drying, pyrolyzing and annealing, repeating the dropping, uniformly coating, solidifying, drying, pyrolyzing and annealing processes, and obtaining a bismuth ferrite-based ferroelectric polycrystal film with a required thickness. The sol-gel method is adopted to prepare the multi-element isometric solid solution ferroelectric film, so that accurate component control can be realized, the growth of the material on a large-area substrate is suitable, the equipment and synthesis steps are simple, the material is saved, the cost is low, industrialized production is easy to realize, and the prepared ferroelectric polycrystal film has excellent self-polarization characteristics and a high piezoelectric coefficient, so that the ferroelectric polycrystal film has a wide application prospect in the field of electronic material technology.

The application discloses a low-loss high-Curie-point bismuth ferrite-barium titanate lead-free piezoelectric ceramic material and a preparation method thereof. 1.02 FeO3-(0.25-x)BaTiO3-xCaZrO3+y%GeO2+z%MnO2; wherein x, y and z represent molar fractions, 0.005<=x<=0.020, 0.3<=y<=1, 0.5<=z<=1.5. The application introduces the third component CaZrO3, and adds GeO2 and MnO2, controls the crystal phase composition and the conductive carrier concentration, improves the microstructure, reduces the loss and improves the temperature stability, so that the Curie temperature, the depolarization temperature and the piezoelectricity are obviously improved. The lead-free piezoelectric ceramic material provided by the application has a simple synthesis process, and is expected to be applied to the preparation of high-temperature piezoelectric sensor devices.

The invention discloses a method for preparing a heterogeneous metal catalyst based on waste lithium cobalt oxide modified bismuth ferrite and application, relates to the field of solid waste resource utilization and beneficiation wastewater treatment, and synchronously solves the environmental problems of biomass-waste positive electrode solid waste treatment, beneficiation wastewater treatment and the like. The method comprises the following steps: carrying out mechanical wet grinding on biomass waste and a waste lithium battery positive electrode material, then introducing organic acid with coordination-precipitation dual functions to leach wet-ground slurry, and carrying out solid-liquid separation to directly obtain cobalt-containing leached residues; then heterogeneous metal doping is carried out on the multiferroic Bi2Fe4O9 (BFO) to construct the Co3O4-C / BFO composite catalyst with a stable heterogeneous interface, and the Co3O4-C / BFO composite catalyst is applied to removal of black powder in beneficiation wastewater. According to the method, waste lithium battery recycling, biomass solid waste conversion and functional catalyst modification are deeply fused, the problems that a traditional wet method is long in technological process, low in metal separation efficiency and high in catalyst preparation cost are solved, and an efficient and low-carbon solution is provided for solid waste recycling and industrial wastewater cooperative treatment.

The invention discloses a preparation method of a functionalized palladium quantum dot loaded bismuth ferrite nanorod piezoelectric catalytic hydrogen evolution material, and belongs to the technical field of new energy catalytic materials. According to the invention, a palladium quantum dot loaded bismuth ferrite nanorod (Pd-BFO) cocatalyst is constructed by a simple method of electrostatic spinning and chemical reduction. The material can be used as a mechanical energy and chemical energy conversion platform and is used for efficient piezoelectric catalytic hydrogen evolution reaction. Under ultrasonic irradiation, the strong piezoelectric response of bismuth ferrite can induce ferroelectric polarization, and a built-in polarization field is formed to separate charges. Palladium quantum dots serve as a cocatalyst, transfer and enrichment of polarized charges can be promoted, the charge separation efficiency is improved, meanwhile, water adsorption and hydrogen desorption energy barriers are optimized, and therefore the piezoelectric catalytic hydrogen evolution activity is remarkably improved. The 0.5 wt% Pd-BFO material obtained through optimization can achieve the excellent hydrogen evolution rate of 4253.44 [mu] mol.g <-1 >. H <-1 >, and the performance of the Pd-BFO material is superior to that of most reported piezoelectric catalysts at present.

Sulfur-incorporated bismuth ferrite nanoparticles (SBFNPs) contain Bi2Fe4O9 nanoparticles doped with Fe(0) and Bi(0) and sulfur in an amount of 0.5 to 5 percent by weight. At least a portion of bismuth is bonded to at least a portion of the sulfur and at least a portion of iron is bonded to at least a portion of the sulfur. The bismuth ferrite nanoparticles have a longest dimension of 1 to 50 nm. A method of photocatalytic degradation of dyes and a method of hydrogen generation and storage using the nanoparticles.

The invention belongs to the field of piezoelectric electro-catalysis, and relates to preparation of a defect-state tungsten oxide coated bismuth ferrite nano material and piezoelectric electro-catalysis application of the defect-state tungsten oxide coated bismuth ferrite nano material. The preparation method comprises the following steps: firstly, preparing a bismuth ferrite nano-material through a coprecipitation method, then mixing the bismuth ferrite nano-material with tungstic acid, and calcining in hydrogen to prepare a defect-state tungsten oxide-coated bismuth ferrite nano-material (WO3-x / BFO), so that the sunlight absorption capacity of WO3-x / BFO is remarkably improved, and the defect-state tungsten oxide-coated bismuth ferrite nano-material has the advantages that the defect-state tungsten oxide-coated bismuth ferrite nano-material is obtained; meanwhile, the heterostructure and the piezoelectric potential effect are both beneficial to effective separation of photon-generated carriers, and the piezoelectric electro-catalytic performance is remarkably enhanced. Under the synergistic effect of ultrasound and light, efficient degradation of rhodamine B can be achieved through WO3-x / BFO, and the degradation rate constants are 2.03 times and 21.22 times that of WO3 / BFO and BFO respectively. The preparation method of the defect-state tungsten oxide coated bismuth ferrite nano material and the application of the defect-state tungsten oxide coated bismuth ferrite nano material in piezoelectric electro-catalytic degradation of organic pollutants are illustrated, the technological process is simple, and the application prospect is wide.

The invention discloses a microwave hydrothermal preparation method of a BiFeO3 / CoFe2O4 two-dimensional single-crystal heterojunction multiferroic material. The microwave hydrothermal preparation method comprises the following steps: 1) preparing an oxyhydroxide precipitate suspension containing iron and cobalt; (2) adding bismuth ferrite single crystal nanosheets and a mineralizer into the suspension prepared in the step (1), and uniformly stirring to obtain a reaction material; (3) transferring the reaction material prepared in the step (2) into an inner container of a microwave reaction kettle, adjusting the volume of the reaction material in the inner container of the reaction kettle to 70-90% of the volume of the inner container of the reaction kettle by using deionized water, and uniformly stirring; (4) putting the microwave reaction kettle inner container into a microwave reaction kettle, putting the microwave reaction kettle into a microwave hydrothermal instrument for microwave hydrothermal treatment, raising the temperature to 200-240 DEG C in a staged temperature raising manner, and keeping the temperature for 5-2 hours; and 5) after the microwave hydrothermal reaction is completed, naturally cooling the microwave reaction kettle to room temperature, repeatedly washing a reaction product with deionized water and absolute ethyl alcohol, filtering and drying to obtain the BiFeO3 / CoFe2O4 two-dimensional single crystal heterojunction multiferroic material.

The invention relates to a preparation method of an ultrathin carbon nitride / bismuth ferrite piezoelectric catalytic composite material, which comprises the following steps: S1, putting a carbon nitride precursor into a crucible, calcining in a muffle furnace to obtain blocky nitrogen carbide, grinding and sieving; putting the sieved carbon nitride fine powder into a muffle furnace for secondary calcination to obtain ultrathin carbon nitride; and S2, dispersing bismuth ferrite nanosheets in deionized water, adding the ultrathin carbon nitride obtained in the step S1, magnetically stirring for 4-6 hours, washing with deionized water, and drying to obtain the ultrathin carbon nitride / bismuth ferrite piezoelectric catalytic composite material. The prepared composite material has high oxidability and reducibility, and hydrogen peroxide can be efficiently produced while hydrogen is produced in pure water. The g-C3N4 is obtained by adopting a two-step thermal stripping method, participation of other chemical reagents or long-time ultrasonic treatment is not needed, and the price and time cost are reduced.

This application belongs to the interdisciplinary fields of semiconductor optoelectronic devices, multiferroic materials, and neuromorphic computing. Specifically, it discloses an in-situ differential optoelectronic synaptic device and its in-memory computing method. The method involves grounding the first and second electrodes, applying a voltage to the bottom electrode to change the polarization direction of the ferroelectric domains in the bismuth ferrite thin film, and using the polarization direction of the ferroelectric domains as the weight symbol in the neural weights to set the non-volatile synaptic weights. The voltage on the bottom electrode is then removed or reduced, and a light spot is used to illuminate the bismuth ferrite thin film. By adjusting the position of the light spot, the differential current between the first and second electrodes is read and used as the weight value in the neural weights, thus realizing the read operation. This application achieves integrated storage and computing.

This piezoelectric film substrate 100 comprises a substrate 1, a seed layer 2, a lower electrode layer 3, an adjustment layer 4, a piezoelectric layer 5, and an upper electrode layer 6. The seed layer 2 contains a zirconium oxide formed by an epitaxial growth layer on the substrate 1 composed of a (100) silicon single crystal. The lower electrode layer 3 contains at least one among iridium and platinum formed by an epitaxial growth layer on the seed layer 2. The adjustment layer 4 contains a metal oxide having a perovskite structure formed by an epitaxial growth layer on the lower electrode layer 3. The piezoelectric layer 5 is composed of bismuth ferrite preferentially oriented to (100) on the adjustment layer 4.

The invention provides a bismuth ferrite interface modified perovskite solar cell. The solar cell sequentially comprises a conductive substrate, an electron transport layer, a bismuth ferrite interface layer, a perovskite light absorption layer, a hole transport layer and a second electrode from bottom to top. The thickness of the bismuth ferrite interface layer is 5-15 nm, and the bismuth ferrite interface layer is composed of superfine powder with the particle size of 3-10 nm. According to the invention, the bismuth ferrite interface layer is introduced, lattice matching is realized by using the lattice constant of the bismuth ferrite interface layer similar to that of the perovskite layer, and interface defects and stress generation are inhibited from the source; and meanwhile, a polarization electric field is formed at an interface by utilizing ferroelectric characteristics, so that separation and transmission of carriers are actively promoted. Experiments show that the photoelectric conversion efficiency of the perovskite solar cell is improved from 21.79% to 24.03%, the hysteresis coefficient is reduced from 2.66% to 0.27%, and the photoelectric property and the stability of the device are remarkably improved.

The invention relates to the technical field of dielectric refrigeration device materials, in particular to bismuth ferrite-based lead-free ferroelectric ceramic with a negative electrocaloric effect as well as a preparation method and application of the bismuth ferrite-based lead-free ferroelectric ceramic, the chemical composition of the bismuth ferrite-based lead-free ferroelectric ceramic is 0.7 BiFe < 0.999 > Mn < 0.001 > O < 3-0.3 > BaTi < 1-x > Sn < x > O < 3 >, and x is greater than or equal to 0 and less than or equal to 0.1. The bismuth-ferrite-based lead-free ferroelectric ceramic has a wide working temperature area, a working temperature range close to room temperature and a relatively large negative electrocaloric effect, does not cause harm to the ecological environment and human health in the preparation, use and waste processes, and is suitable for development of miniature refrigerators in the future.

The invention relates to a high-temperature self-stabilization ferroelectric domain wall memory based on bismuth oxide (BFO) and a preparation method thereof, a memory function layer is formed by sequentially depositing an STO buffer layer with the thickness of 5 nm, a BFO film with the thickness of 100 nm and a planar Pt electrode pair on a strontium titanate (STO) substrate in the [001] direction, the STO substrate is obliquely cut by 0.2 degree in the [100] direction, the BFO film is of a stripe domain structure, and the electrode gap is not smaller than 500 nm. Through the limiting effect of a beveled substrate step, the BFO ferroelectric film only forms two polarization orientations, a periodic stripe domain structure is obtained, the polarization overturning controllability is improved, the electrode is prepared by adopting an electron beam photoetching and ion etching combined process, the electric domain overturning is ensured to penetrate through the film thickness, and the performance of the BFO ferroelectric film is improved. After 105 times of voltage pulse cycles at a high temperature of 135 DEG C, the device still keeps a rectification ratio greater than or equal to 25: 1, the turnover polarization retentivity is high, and the domain wall current attenuation rate is small. The bottleneck that a traditional FeRAM fails in a high-temperature environment is broken through, the storage density potential is larger than 1 Gb, and the FeRAM has the effect of being suitable for high-temperature application scenes such as aerospace, vehicle-mounted electronics and geothermal exploration.

The present invention belongs to the technical field of piezoelectric ceramics, and discloses a bismuth ferrite-barium titanate lead-free piezoelectric ceramic material and a preparation method thereof. The composition of the piezoelectric ceramic is 0.7Bi 1.02 FeO3 - 0.3BaTiO3 - x% LiF + y% M + z% SiO2; M represents a Mn-containing metal compound; x, y, and z respectively represent the molar fractions of LiF, M, and SiO2, 0.25 ≤ x ≤ 0.75, 0.35 ≤ y ≤ 0.75, 0 ≤ z ≤ 0.3. The present invention also discloses a preparation method of the piezoelectric ceramic. The present invention regulates the oxygen vacancy concentration in the crystal lattice, strengthens the crystal lattice distortion, improves the microstructure, and significantly improves both the piezoelectricity and the Curie temperature. The piezoelectric ceramic material of the present invention has a wide sintering temperature range (880 - 1020 °C), a high piezoelectric constant (d 33 = 180 - 208 pC / N), and a high Curie temperature (T C = 550 °C).

The present invention discloses a calcium-doped bismuth ferrite (Bi 1‑ x Ca x FeO3) thin film system material preparation method, the method specifically includes the following steps: solution preparation, gel and powder preparation, target material preparation, bottom electrode target material preparation, target material and substrate processing, thin film growth environment control, thin film preparation; the present invention adopts solvent gel method to ensure the mixing of various components at the molecular level, the ceramic target material has high density, and the epitaxially grown thin film has high phase purity; the present invention introduces different concentrations of oxygen vacancies by adjusting the calcium doping ratio, thereby enhancing the conductivity of the film, and has great potential application value; the present invention introduces Bi 1‑x Ca x La with small lattice constant difference from FeO3 0.5 Sr 0.5 The MnO3 electrode material is used as the bottom electrode, which makes the epitaxially grown film have atomic-level flat steps, which is conducive to epitaxial growth, reduces defect density, improves film crystallization quality, and enhances device performance and life.