73 results about "Bismuth ferrite" patented technology

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 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 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.

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 application discloses a preparation method of bismuth ferrite nanometer islands based on a molecular beam epitaxy method, and comprises the following steps: conveying a substrate into a molecular beam epitaxy (MBE) growth chamber, wherein the substrate temperature is greater than or equal to the evaporation temperature of a Bi source; heating the Bi source and a Fe source to the evaporation temperature, and adjusting the beam current of the Bi source and the Fe source; using pure ozone as an epitaxial growth atmosphere, adjusting the pressure of the growth chamber to 2*10 ‑6 -1*10 ‑ 5 Torr, mixing the Bi source and the Fe source in the growth chamber to perform epitaxial growth; and cooling to obtain bismuth ferrite epitaxial nanometer islands. The application further discloses the bismuth ferrite nanometer islands obtained by the preparation method and application of the bismuth ferrite nanometer islands in a ferroelectric memory. The preparation method can realize large-area integration of the bismuth ferrite epitaxial nanometer islands, does not introduce a second phase such as a template, has simple process steps, and is high in preparation efficiency; the prepared bismuth ferrite nanometer islands have good integration, are relatively independent between each nanometer island, can perform independent writing and erasing of information, can effectively bind a domain wall position, and improve the service life of the memory.

The application belongs to the field of nanomaterial piezoelectric photocatalysis, and relates to a preparation method of a defect state tungsten oxide coated bismuth ferrite nanomaterial (WO 3‑x / BiFeO3) and application of the nanomaterial in the field of piezoelectric photocatalysis. WO 3‑x / BiFeO3 is synthesized by a hydrothermal method, WO 3‑x The application has excellent light absorption capacity in the visible to near infrared region, and enhances effective utilization of sunlight by the composite material. BiFeO3 can form a piezoelectric field under ultrasonic action, provides driving force for photo-induced charges, suppresses photo-induced electron-hole recombination, and can bend a band and narrow a band gap, which is helpful to piezoelectric photocatalytic decomposition of organic pollutants and decomposition of water to produce hydrogen. The piezoelectric photocatalytic degradation efficiency of methylene blue by WO 3‑x / BiFeO3 is 3.29 times that of BiFeO3, the piezoelectric photocatalytic hydrogen production amount is 4.86 times that of BiFeO3, and the piezoelectric photocatalytic performance is significantly improved. The application describes a preparation method of a defect state tungsten oxide coated bismuth ferrite nanomaterial and application of the nanomaterial in piezoelectric photocatalytic degradation of organic pollutants and decomposition of water to produce hydrogen, and the preparation process flow is simple and has wide application prospect.

The invention provides a lead-free (La, Bi) FeO3 film with an adjustable polymorphic negative capacitance effect and a preparation method thereof. The lead-free (La, Bi) FeO3 film comprises a substrate layer, and a first electrode layer, a ferroelectric material layer and a second electrode layer which are sequentially stacked on the substrate layer, the ferroelectric material layer comprises bismuth ferrite doped with rare earth elements, and the doping content of the rare earth elements in the bismuth ferrite is 15%-30%. According to the lead-free (La, Bi) FeO3 thin film, the ferroelectricity of bismuth ferrite is converted, steady-state negative capacitance is achieved, and lead-free, high polarization intensity and adjustable phase change voltage are achieved.

This invention relates to the field of dielectric materials technology, specifically to a multi-element rare earth-doped modified bismuth ferrite-based ceramic and its preparation method. The method employs a standard solid-state reaction sintering process, which includes drying the raw materials, weighing them according to the correct stoichiometric ratio, batching, ball milling, drying, sieving, and pressing to obtain a BiFeO3-based ceramic green body. Finally, it is sintered at a high temperature of 900℃ to form a ceramic. This ceramic exhibits good ferroelectricity and magnetism, and possesses excellent magnetoelectric coupling. Furthermore, the preparation method is simple to implement and can be mass-produced.

This invention relates to electronic material development and thin film material preparation technology, specifically to a bismuth ferrite film material, its preparation method, and its applications. The preparation method includes: sequentially magnetron sputtering a bottom electrode, a bismuth ferrite film, and a top electrode onto a silicon substrate surface from bottom to top; wherein the bottom and top electrodes are made of inert metals; the gas atmosphere for magnetron sputtering the bottom electrode is a mixture of argon and oxygen, and the magnetron sputtering temperature is 200–400°C; the gas atmosphere for magnetron sputtering the bismuth ferrite film is a mixture of argon and oxygen, and the magnetron sputtering temperature is 300–500°C; the gas atmosphere for magnetron sputtering the top electrode is argon, and the magnetron sputtering temperature is 25–150°C. The bismuth ferrite film material provided by this invention, by adjusting the gas atmosphere during bottom electrode sputtering, changes the growth orientation of the bismuth ferrite material, thereby improving the overall piezoelectric properties of the bismuth ferrite film material. It eliminates the need for a buffer layer, doping with any elements, or high-temperature annealing, making the preparation method simpler.

The invention discloses a FeTiO3-BiFeO3 heterojunction. The FeTiO3-BiFeO3 heterojunction is of a p-n heterojunction structure formed by ferrous titanate and bismuth ferrite according to the mass ratio of 1: (0.5-2). The preparation method comprises the following steps: (1) preparing ferrous titanate powder by utilizing a hydrothermal synthesis method; (2) preparing bismuth ferrite powder by using a hydrothermal synthesis method; (3) adding water into the ferrous titanate powder, carrying out uniform ultrasonic dispersion, then adding the bismuth ferrite powder, carrying out ultrasonic dispersion, and then continuously stirring and mixing to obtain a mixed dispersion liquid; (4) putting the mixed dispersion liquid into a reaction kettle, carrying out hydrothermal reaction, and carrying out solid-liquid separation after the reaction is finished; and washing the solid precipitate obtained by separation, and then drying the solid precipitate to obtain the FeTiO3-BiFeO3 heterojunction. When the material is used for preparing the anode material of the lithium battery, the technical problems of poor lithium storage performance, electrochemical performance, cycling stability and the like of the existing ferrous titanate anode material can be effectively solved.