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

The invention discloses a Bi[1-X]HoXFeO3 ferroelectric film with a high dielectric constant and a preparation method of the film. According to the invention, in the Bi[1-X]HoXFeO3, X is 0.04-0.12; the film has a twisty perovskite structure, is in rhombohedral system and good in uniformity, has spatial point group of R-3m(160), and has a dielectric constant of 199.3-299.0 under the frequency of 1kHz. The preparation method comprises the following steps: dissolving bismuth nitrate, ferric nitrate and holmium nitrate into a mixed liquid of ethylene glycol monomethyl ether and acetic anhydride in a mole ratio of (1.05-x):1:x to obtain a precursor liquid; carrying out spin coating on a substrate with the precursor liquid, roasting after uniformly dividing glue, and then annealing to obtain the Bi[1-X]HoXFeO3 film; and repeatedly carrying out spin coating, roasting and annealing until required film thickness is achieved, thereby obtaining the Bi[1-X]HoXFeO3 ferroelectric film with the high dielectric constant. According to the invention, equipment requirement is simple, doped amount is easy to control, and the dielectric property 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 relates to a high-dielectric-constant Bi[1-x]DyxFeO3 film (x=0.06-0.08) and a preparation method thereof. The film is in a rhombohedral structure and has favorable uniformity; the space point group is R-3m(166); and under the frequency of 1kHz, the dielectric constant is 152.8-241.6. The preparation method comprises the following steps: dissolving bismuth nitrate, iron nitrate and dysprosium nitrate in an ethylene glycol monomethyl ether-acetic anhydride mixed solution in a mole ratio of (1.05-x):1:x to obtain a precursor solution; evenly spin-coating the precursor solution on a substrate, baking to obtain a dry film, and annealing to obtain a Bi[1-x]DyxFeO3 film; and spin-coating the precursor solution again, baking and annealing to the required film thickness, thereby obtaining the high-dielectric-constant Bi[1-x]DyxFeO3 film. The method has the advantages of simple facility request and controllable doping amount, and can greatly enhance the dielectric properties of the BiFeO3 film.

The invention discloses a Tb, Cr and Mn ternary co-doped high-remanent-polarization BiFeO3 film and a preparation method thereof. The preparation method comprises the following steps: dissolving bismuth nitrate, ferric nitrate, terbium nitrate, chromic nitrate and manganese acetate according to a molar ratio of (0.91-0.97):(0.98-x):(0.08-0.14):0.02:x in a mixed solution of ethylene glycol monomethyl ether and acetic anhydride and uniformly stirring, thus obtaining 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 0.04; spin coating the BiFeO3 precursor solution on an 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; and after the crystalline-state BiFeO3 film is cooled, repeating the operations until the BiFeO3 film reaches the needed thickness, thus obtaining the Tb, Cr and Mn ternary 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 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.