61results about How to "Improve multiferroic properties" patented technology

The invention provides a preparation method of a low-leakage current Bi0.92Tb0.08Fe(1-x)CrxO3 film. The method comprises the following steps of: dissolving bismuth nitrate, ferric nitrate, terbium nitrate and chromic nitrate at a molar ratio of 0.97:(1-x):0.08:x into the mixed solution of ethylene glycol monomethyl ether and acetic anhydride to form a mixed solution; adding ethanolamine into the mixed solution to adjust the viscosity and the complexing degree to obtain a stable BiFeO3 precursor liquid; and preparing a Tb and Cr co-doped crystalline BiFeO3 film by a spin-coating method and layer-by-layer annealing technology. The film is a crystalline Bi0.92Tb0.08Fe0.99Cr0.01O3 film, wherein the leakage current density is still kept below 10<-4>A/cm<2> in a 150kv/cm test electric field. According to the method provided by the invention, the requirements on equipment are simple, the experimental conditions are easy to realize, the prepared film has good uniformity, and the leakage current of the film is reduced through the co-doping of Tb and Cr.

The invention discloses a Bi0.92Dy0.08Fe(1-x)MnxO3 ferroelectric film with a low coercive field and a preparation method of the film. In Bi0.92Dy0.08Fe(1-x)MnxO3, x is 0.01-0.05; the film is of a rhombohedral structure and is good in uniformity; the residual polarization intensity is 58.27-69.87 muC/cm<2>; the coercive field is 318-448kV/cm; the dielectric constant is 214.4-260.6. The preparation method comprises the following steps: dissolving bismuth nitrate, ferric nitrate, dysprosium nitrate and manganese acetate into a mixed solution prepared from ethylene glycol monomethyl ether and acetic oxide in a mixing manner, so as to obtain a precursor solution; spinning the precursor solution on a substrate; baking after spinning to obtain a dry film; annealing to obtain the Bi0.92Dy0.08Fe(1-x)MnxO3 film; repeatedly spinning the precursor solution, baking and annealing to achieve the required film thickness, so as to obtain the film. According to the invention, equipment requirements are simple, doping content is easy to control, and the ferroelectric properties of the BiFeO3 film can be greatly improved.

The invention provides a laminated BiFe(0.97-x)Mn0.03TMxO3/CoFe2O4 multiferroic composite film and a preparation method thereof. The composite film comprises a BiFe(0.97-x)Mn0.03TMxO3/CoFe2O4 crystallized film and a CoFe2O4 crystallized film which are compounded together. The preparation method comprises the following steps of firstly, preparing a BiFe(0.97-x)Mn0.03TMxO3/CoFe2O4 precursor solution and a CoFe2O4 precursor solution respectively; and then carrying out spin coating on a substrate to prepare a multi-layer CoFe2O4 film, and then carrying out spin coating on the CoFe2O4 film so as to prepare a multi-layer BiFe(0.97-x)Mn0.03TMxO3/CoFe2O4 film, thereby obtaining the target product. According to the invention, the equipment requirement is simple; the prepared film is good in uniformity; chemical components are accurate and controllable; the doped amount is easy to control; the ferroelectric properties and the ferromagnetic property of a film are improved greatly, so that the film has high residual polarization value and a residual magnetization value.

The invention relates to a B-site Mn and Cu codoped high remanent polarization BiFeO3 film and a preparation method, the method comprises the following steps: dissolving bismuth nitrate, ferric nitrate, manganese acetate and cupric nitrate according to mol ratio of 1.05: [(0.92-0.98)-x]: (0.02-0.08):x in a mixed liquor of ethylene glycol monomethyl ether and acetic anhydride, then uniformly stirring to obtain a BiFeO3 precursor; wherein total metal ion concentration of the BiFeO3 precursor is 0.1-0.5mol/L, X is 0.01-0.03; performing spin coating of the BiFeO3 precursor on a FTO/glass substrate to prepare a wet membrane, baking the wet membrane to obtain a dry membrane, then annealing at 550 DEG C to obtain the crystalline state BiFeO3 film; cooling the crystalline state BiFeO3 film, and repeatedly making the crystalline state BiFeO3 film to reach a required thickness to obtain the B-site Mn and Cu codoped high remanent polarization BiFeO3 film. According to the invention, a sol gel technology is employed, the equipment requirement is simple, the film is prepared on large surface and surfaces with irregular shapes, the chemical component is accurate and controllable, and the regulation and control to its crystal structure can be carried out by codoping thereby the ferroelectric performance of the film is greatly increased.

The invention relates to novel room-temperature multi-ferroic ceramic with high polarization intensity and a preparation method of the novel room-temperature multi-ferroic ceramic. The chemical composition of a room-temperature multi-ferroic ceramic material is 0.75 ((1-x)BiFeO<3>-xBiGaO<3>)-0.25Ba<0.85>Ca<0.15>Ti<0.90>Zr<0.10>O3 +yMnCO<3>, wherein x is greater than 0 and is smaller than or equal to 0.05, and y is smaller than or equal to 0.5wt%. By adjusting and controlling components, the novel room-temperature multi-ferroic ceramic material simultaneously having excellent ferromagnetism and excellent ferroelectricity is obtained, and has high remanent polarization intensity (22-44 [mu]C/cm<2>) and high ferromagnetism properties (0.09-0.27emu/g).

The invention provides a Bi1-xRExFeO3/CoFe2O4 multiferroic composite membrane and a preparation method thereof. The composite membrane comprises a Bi1-xRExFeO3 crystalline state membrane and a CoFe2O4 crystalline state membrane which are combined together, wherein RE is Ce, Pr, Tb, Eu or Yb, x is equal to 0.05-0.15; in the preparation, Bi1-xRExFeO3 precursor solution and CoFe2O4 precursor solution are firstly prepared respectively; and then, multi-layer CoFe2O4 membrane is prepared by spinning on a substrate, and the multi-layer Bi1-xRExFeO3 membrane is prepared by spinning on the CoFe2O4 membrane, so the target product is obtained. The facility request is simple, the homogeneity of the prepared membrane is good, the chemical composition can be accurately controlled, the doping content is easily controlled, and the ferroelectric property and ferromagnetic property of the membrane are greatly improved, so the Bi1-xRExFeO3/CoFe2O4 multiferroic composite membrane has high residual polarization value and residual magnetization value.

The invention discloses a BiFe1-XMnXO3 ferroelectric film with high remnant polarization and a preparation method thereof, and x is equal to 0.02-0.08. The BiFe1-XMnXO3 ferroelectric film is of a twisty perovskite structure, belongs to a rhombohedral system, and is good in uniformity. At the frequency of 1kHz, the remnant polarization is 100-130.4mu C/cm<2>. The preparation method comprises the steps of: dissolving bismuth nitrate, ferric nitrate and manganese acetate in a mixed solution of ethylene glycol monomethyl ether and acetic anhydride according to a molar ratio of 1.05:(1-x) to obtain a precursor solution; and spinning the precursor solution on a substrate, homogenating and baking to obtain a dry film; annealing to obtain the BiFe1-XMnXO3 ferroelectric film, repeatedly carrying out the steps of spinning the precursor solution, baking, and annealing till a required film thickness is reached, thus obtainng the BiFe1-XMnXO3 ferroelectric film with high remnant polarization. The BiFe1-XMnXO3 ferroelectric film is simple in requirement of equipment, easily controllable in doping amount, and capable of greatly improving ferroelectric properties and dielectric properties of a BiFeO3 film.

The invention discloses a preparation method of yttrium, europium and manganese codoped bismuth ferrite. The method comprises the following steps of S01, weighing and taking Y2O3, Eu2O3 and Bi2O3 intonitric acid; performing stirring until a clear solution is obtained; S02, adding MnO and Fe(NO3)3.9H2O into the solution obtained in S01 according to the proportion of the quantity sum of three element substances of Y, Eu and Bi to the quantity sum of the two kinds of element substances of Mn and Fe to be 1:1; performing full and continuous stirring to obtain a precursor solution; S03, adding tartaric acid and deionized water into the precursor solution obtained in the S02; performing continuous stirring to form xerogel; S04, putting the xerogel obtained in the S03 in a drying box; performingpreroasting for 2h at 250 DEG C; then, performing sintering annealing for 2h under the condition of 550 DEG C. The invention also discloses the yttrium, europium and manganese codoped bismuth ferriteprepared by the preparation method. The yttrium, europium and manganese codoped bismuth ferrite and the preparation method of the yttrium, europium and manganese codoped bismuth ferrite provided by the invention have the advantages that the process is simple; the crystallinity degree is high; the current leakage density can be reduced.

The invention provides a GdSrMnCo codoped bismuth ferrite superlattice film and a preparation method thereof. A Bi0.91Gd0.06Sr0.03Fe0.94Mn0.04Co0.02O3/Bi0.88Gd0.09Sr0.03Fe0.94Mn0.04Co0.02O3 superlattice film, namely the GdSrMnCo codoped bismuth ferrite superlattice film, is prepared from bismuth ferrite films doped according to different Gd concentrations, wherein the crystal structures of the bismuth ferrite films are trigonal structures and the space groups thereof are in a coexistent state of R3c: H and R3m: R. In the preparation method, a sol-gel process is adopted, and a spin coating and layer-by-layer annealing method is adopted; equipment requirements are low; the preparation method is suitable for preparing films on large surfaces and irregularly-shaped surfaces; and chemical components are precise and controllable; the multi-ferrous performance of BiFeO3 films can be improved.

The invention provides a method for preparing multi-ferrous composite ceramic material by low-temperature magnetic field heat treatment. According to the method, BaTiO3-BaFe12O19 composite ceramic is subjected to heat treatment by an external magnetic field, so that the multiferroic performance of the composite ceramic is improved. The method comprises the steps as follows: preparing nanoBaTiO3 and BaFe12O19 powder with a hydrothermal method or a microwave hydrothermal method, preparing a BaTiO3-BaFe12O19 blank sample A from nanoBaTiO3 and the BaFe12O19 powder in a ratio of (1-x):x by uniform mixing; sintering the blank sample A in a microwave sintering furnace to obtain BaTiO3-BaFe12O19 composite ceramic B after cooling with the furnace; putting the obtained composite ceramic B in a magnetic field sintering furnace in a nitrogen atmosphere for low-temperature heat treatment at a magnetic flux current of 10-14 A and a temperature of 400-450 DEG C, and preserving heat for 60-90 minutes to obtain the composite ceramic material with excellent multiferroic performance. The method has the advantages that the maximum magnetization strength of the material is increased by about 80% and the maximum polarization strength is improved by about 11% with the addition of a low-temperature magnetic field heat treatment process during preparation of ceramic, , and the method is low in preparation cost, easy to operate, environment-friendly and pollution-free in process and does not require rapid quenching after magnetic field heat treatment.

The invention discloses a B-site Mn and Ni co-doped high-remanent-polarization BiFeO3 film and a preparation method thereof. The preparation method comprises the following steps: dissolving bismuth nitrate, ferric nitrate, manganese acetate and nickel acetate according to a molar ratio of 1.05:[(0.92-0.98)-x]:(0.02-0.08):x in a mixed solution of ethylene glycol monomethyl ether and acetic anhydride, uniformly stirring to obtain a BiFeO3 precursor solution, wherein the total metal ion concentration in the BiFeO3 precursor solution is 0.1-0.5mol/L, and x is equal to 0.01 to 0.03; spin coating the BiFeO3 precursor solution on a FTO/glass substrate to prepare a wet film, baking the wet film to obtain a dried film, annealing at the temperature of 550 DEG C for 8-13 minutes, thus obtaining a crystalline state BiFeO3 film; repeatedly operating until the BiFeO3 film reaches the needed thickness after the crystalline state BiFeO3 film is cooled, thus obtaining the B-site Mn and Ni co-doped high-remanent polarization BiFeO3 film. According to the method, a sol-gel process is adopted, the equipment requirement is simple, the method is suitable for preparing films on large surfaces and out-of-shape surfaces, the chemical constituents are accurately controlled, and the crystal structure is regulated through co-doping, so that the ferroelectric properties of the film are greatly improved.

The invention belongs to the technical field of yttrium doped bismuth ferrite preparation, and discloses a preparation method of pure phase nanocrystalline yttrium doped bismuth ferrite. According tothe method, iron oxide, bismuth oxide and yttrium oxide are used as raw materials, the above raw materials are subjected to high-energy ball milling by a mechanical alloying method to obtain amorphousyttrium doped bismuth ferrite, and the amorphous yttrium doped bismuth ferrite is subjected to high-temperature heat treatment to produce the pure yttrium doped bismuth ferrite nanocrystalline structure. The yttrium doped bismuth ferrite prepared by the method has good multiferroic property and superior photo-catalytic effects.

The invention provides a HoSrMnZn co-doped bismuth ferrite multiferroic film and a preparation method thereof. According to the invention, bismuth nitrate, holmium nitrate, strontium nitrate, ferric nitrate, manganese acetate and zinc nitrate are used as raw materials (wherein bismuth nitrate is 5% excess in amount), ethylene glycol monomethyl ether and acetic anhydride are used as solvents, and a spin-coating process and a layer-upon-layer annealing process are employed to prepare a Bi<0.89>Ho<0.08>Sr<0.03>Fe<0.97-x>Mn<0.03>Zn<x>O<3> multiferroic film, i.e., the HoSrMnZn co-doped bismuth ferrite multiferroic film. According to the invention, a sol-gel process is employed, and the spin-coating and layer-upon-layer annealing processes are utilized; requirements on equipment are simple; experimental conditions are easy to realize; the preparation method is suitable for preparation of films on large surfaces and surfaces with irregular shapes and allows chemical components to be accurate and controllable; and the prepared HoSrMnZn co-doped bismuth ferrite multiferroic film has good uniformity and improves the multiferroic performance of a BiFeO3 film.

The invention provides a Bi1-xRExFe1-yTMyO3/CoFe2O4 multiferroic composite film and a preparation method thereof. The composite film comprises a Bi1-xRExFe1-yTMyO3 crystalline film and a CoFe2O4 crystalline film which are compounded together. The preparation comprises the following steps: firstly preparing Bi1-xRExFe1-yTMyO3 precursor solution and CoFe2O4 precursor solution respectively; then spin-coating to prepare a plurality of layers of CoFe2O4 films on a substrate; next preparing a plurality of layers of Bi1-xRExFe1-yTMyO3 films on the CoFe2O4 films through spin coating to obtain a target product. The equipment requirement is simple, the prepared film is good in uniformity, chemical components are accurate and controllable, the doping content is easy to control, and the ferroelectric property and the ferromagnetic property of the film are greatly improved, and the film has high residual polarization value and residual magnetization value.