48results about How to "Easy to dope and modify" patented technology

The invention discloses a layer-by-layer alternatively doped low-leakage-current BiFeO3 film and a preparation method thereof. The preparation method comprises the steps of dissolving bismuth nitrate, ferric nitrate and nitric acid into mixed liquid of ethylene glycol monomethyl ether and acetic anhydride so as to obtain a precursor solution A; dissolving bismuth nitrate, ferric nitrate and samarium nitrate in mixed liquid of ethylene glycol monomethyl ether and acetic anhydride so as to obtain a precursor solution B; coating the precursor solution A on a FTO/glass substrate by way of spin coating, baking and annealing the FTO/glass substrate so as to obtain a Tb doped crystalline BiFeO3 film, coating the precursor solution B on the Tb doped crystalline BiFeO3 film by way of spin coating, baking and annealing the Tb doped crystalline BiFeO3 film so as to obtain a Sm doped crystalline BiFeO3 film, and alternatively preparing the Tb doped crystalline BiFeO3 film and the Sm doped crystalline BiFeO3 film on the Sm doped crystalline BiFeO3 film so as to obtain the layer-by-layer alternatively doped low-leakage-current BiFeO3 film. The method disclosed by the invention adopts a sol-gel process, and is simple in equipment requirements and suitable for preparing films on large surfaces and irregularly-shaped surfaces, and chemical components are precise and controllable.

The present invention belongs to the field of piezoelectric film material preparing technology, and is water base sol-gel process of preparing high Curie point piezoelectric film. Tetrabutyl titanate and nitrate and acetate of other metal cation as main material and glacial acetic acid and deionized water as main solvent are first prepared into stable sol; and the sol is coated and fast annealed to form the piezoelectric film with compact structure and homogeneous components. The piezoelectric film has excellent piezoelectric performance, Curie point as high as 435 deg.c, crystal grain size of 20-100 nm, effective piezoelectric coefficient d33*of about 80 pC/N, comparable with that of the PZT film, and thickness controllable in 0.15-1 micron. The piezoelectric film is suitable for various piezoelectric ferrite elements and devices used in high temperature, and may find wide application in space, automobile and other industrial fields.

The invention discloses a method for preparing a high-conductivity carbon material by virtue of a hydrothermal method. The method is characterized by comprising the following steps: by taking carboxymethyl cellulose as a raw material and taking pure water as a solvent, performing one-step high-temperature high-pressure hydrothermal treatment on a doping nitrogen source, and performing centrifugal separation, thereby obtaining a deep brown solid product; washing the brown solid product until the filtrate is clarified by using distilled water and absolute ethyl alcohol, performing vacuum drying, and performing high-temperature activation and pyrolysis on the obtained product, thereby obtaining a graphite-like structure carbon material with high nitrogen doping content and developed porous structure, wherein the carbon material has high conductivity and has potential application values in the field of preparation of lithium ion batteries and super-capacitors. The operation process has the main characteristics that the carboxymethyl cellulose is taken as the raw material and is environment-friendly, low in price and readily available, the nitrogen source is doped into carbon in the form of functional groups such as amino, pyridone and pyridine after the hydrothermal reaction and is subjected to high-temperature activation treatment so as to exist in a stable graphite nitrogen form, the graphite-like structure carbon material with high specific surface area and developed porous structure is generated, and high conductivity is promoted. The nitrogen source and the activation conditions are changed, so that carbon materials of different nitrogen doping amounts and pore structures can be controlled to be prepared, the conductivity is further adjusted, the highest conductivity of the prepared material can reach 120-166Sm<-1>, the method is simple and performance is excellent.

The invention belongs to the technical field of electronic ceramic preparation and application, and in particular relates to a method for finely synthesizing ilmenite-structured ZnTiO3 series microwave dielectric ceramic nano powder by using a water-soluble sol-gel process. The method comprises the following steps: 1) preparing a citric acid solution of Zn ions; 2) preparing a citric acid solution of Ti; 3) synthesizing a ZnTiO3 microwave dielectric ceramic nano precursor. As oxides and inorganic nitrate which are low in price are taken as raw materials, and expensive alkoxides are not used, the synthesized powder has the remarkable advantages that the synthesis temperature is low, the ceramic particles are uniform, good dispersity is achieved, the phase is pure, various elements can be finely doped and modified, the prepared powder has the nano particle size (about 30nm), is high in specific surface property and is relatively high in activity, later low-temperature sintering can be achieved, and LTCC application requirements can be possibly met.

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 discloses a method for preparing bismuth titanate (Bi2Ti2O7) ceramic of a pyrochlore structure by means of a solid-phase reaction approach. The method includes the following steps of mixing appropriately excessive TiO2 and Bi2O3,conducting pre-burning at certain temperature,conducting preforming,conducting sintering at the appropriate temperature,and then obtaining the Bi2Ti2O7 ceramic of the pyrochlore structure. The method has the advantage that the Bi2Ti2O7 ceramic of the mono-phase pyrochlore structure can be obtained by means of the conventional solid-phase reaction approach. The preparation mode is simple,the reaction conditions are mild,the cost is low,and the repeatability is high.

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 provides a Nb2O5 doped BaTiO3 substrate-type PTC thermal sensitive ceramic and a preparation method thereof. The constituent chemical formula of a sample is Bam(Ti1-xNbx)O3 and ySiO2, wherein m is equal to 0.994 mol%-1.018 mol%, x is equal to 0.2 mol%-0.8 mol%, y is equal to 0.01 mol%-0.10 mol%. A Nb2O5 doped BaTiO3 substrate-type PTC green body is prepared by adopting a wet-processcasting technology, a substrate-type PTC thermal sensitive ceramic is prepared by adopting a reducing-reoxidizing co-sintering technology, Nb2O5 is introduced to be used as a donor dopant by adoptinga B-bit donor replacing method to perform the doping modification and performance optimization of the sample to obtain a substrate-type PTC thermistor with relatively low resistance, sintering in a reducing atmosphere facilitates widening the semi-conducted interval of a main dopant, a substrate-type PTC thermal sensitive ceramic with high partial stoichiometric ratio (Ba/Ti ratio is within 1.003-1.006) is manufactured by optimizing and regulating the stoichiometric ratio of the sample, and therefore, relatively low room temperature resistance can be obtained, relatively higher lift-drag ratiocan be obtained, and the problem that low resistance and high lift-drag ratio of the sample contradict with each other is solved.

The invention provides a hollow spherical strontium titanate powder, the inner diameter of the hollow spherical strontium titanate powder is 0.6-0.8 μm, and the outer diameter of the hollow spherical strontium titanate powder is 0.8-1.4 μm; The preparation method of the hollow spherical strontium titanate powder comprises the following steps: (1) preparation of a precursor: hydrolyzing tetrabutyl titanate in ethanol or ethanol and ammonia water into an amorphous spherical titanium source precursor; (2) hollow Preparation of spherical powder: Weigh the precursor and strontium nitrate, pour it into the lining of the reaction kettle, add water and sodium hydroxide solution, stir for a period of time, seal it, and put it in an oven for hydrothermal reaction; (3) Cleaning of the powder Drying; the sodium hydroxide solution in the step (2) is used to adjust the pH value of the reaction system, and the mixed solution in the reaction system after the pH adjustment satisfies 13≤pH≤14. It has the characteristics of easier doping modification, easier semiconducting and higher photocatalytic efficiency.

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.

A method for preparing NaxMnO2 electrode materials in a large scale comprises the following steps of: (1) mixing MnO2 with anhydrous NaNO3 according to a mass ratio of 0.5 to 2, and uniformly mixing the spherulitic graphite; (2) calcining the mixture obtained in the step (1) in a muffle furnace at a calcination temperature of 800 to 900 degrees centigrade for 5 to 10 hours; and (3) cleaning the compound obtained in the step (2) with deionized water and drying the compound. The method has a simple process, a low equipment requirement, good practicality and liable to achieve large-scale industrial production. The prepared NaxMnO2 has high Na content and excellent electrochemical performance, including an ultra-wide potential window of 0-1.3V (vs. Ag/ AgCl), high specific capacitance 260 F g-1, and excellent rate performance and cycle stability. The method can prepare a NaxMnO2 electrode material with a special shape and a certain particle size and distribution by controlling a process condition.

The invention discloses a Bi(1-x)DyxFeO3 low leakage current film and a preparation method thereof. X is 0.09-0.12, the film is of a rhombohedral structure and good in uniformity, a space point group is R-3m(166), and the leakage current density is 1.01*10<-8> to 6.39*10<-9> A/cm<2> under the electric field of 117kV/cm. The preparation method comprises the following steps: dissolving bismuth nitrate, ferric nitrate and dysprosium nitrate into a mixed solution prepared from ethylene glycol monomethyl ether and acetic anhydride in a mixing manner according to the molar ratio of (1.05-x):1:x, so as to obtain a precursor solution; spinning a substrate by the precursor solution, baking to obtain a dry film after spinning, and then annealing to obtain a Bi(1-x)DyxFeO3 film; repeatedly spinning the precursor solution, baking and annealing to the required film thickness, so as to obtain the Bi(1-x)DyxFeO3 low leakage current film. The film is simple in demands on equipment, and doping amount is easy to control, and the leakage current density of the Bi(1-x)DyxFeO3 film can be greatly reduced.