SOL-GEL Hydrothermal Perpared Nano SrTiO₃ Powder And Its Surface Coated Mgo Style The Preparation And Properties Of Composite Ceramic

SrTiO3 is a kind of important function of ceramic material, the microstructure and performance largely determines the scope of its use, in order to satisfy the actual demand of the SrTiO3 powder high-purity, superfine and uniform, using sol-gel hydrothermal method to prepare nano SrTiO3 powder this method will sol-gel method and hydrothermal method, not only can reduce the reaction temperature, but also can avoid the high temperature calcination and make the grain growth,, promote the reaction to the good contact between the reactants completely, but powder agglomeration phenomenon is more serious, in order to solve this problem, by using the method of heterogeneous nucleation surface cladding processing to improve the powder dispersion, and to reduce the degree of reunion, better play to its special function effect fo nanoparticles. The main contents and conclusions are as follows:(1) Sol-gel hydrothermal prepared nano SrTiO3 powder. With Ti(C4H9O)4 and Sr(NO3)2 as the main raw materials, glycerin for organic additive, NaOH as the mineral agent, nano SrTiO3 powder which were prepared by sol-gel hydrothermal, its structure is perovskite type, particle size is small, the average particle size is about 108nm, spherical morphology rules. Sol-gel hydrothermal method can effectively reduce the nano SrTiO3 powder synthesis temperature, the minimum can be up to 30℃ to 40℃. Analyzed the influence factors of the preparation of colloid, and the best reaction temperature, ethanol, acetic acid, glycerin and water for the amout of the best and the best concentration of soldium hydroxide.(2) Heterogeneous nucleation of MgO style coating prepared nano SrTiO3 matrix composite ceramics. With CH3(CH2)11SO4Na as dispersant, MgCl2·6H2O as cladding material, the heterogeneous nucleation of the perpared with "core-shell" structure of MgO style coated nanometer SrTiO3 matrix composite ceramics, different amount of MgO style coated on the properties of composite ceramic microstructure and impact. MgO style coated SrTiO3 base composite ceramic forming "core-shell" structure can effectively refine the grain size, increase the density of composite ceramics, up to 4.1g/cm3. With the increase of amount of MgO style coated, the resistivity of composite ceramic gradually increase, dielectric constant decrease, the diffraction peak intensity weaken and move in the direction of low temperature, the breakdown voltage and breakdown field strength has greatly improved. When the amount of MgO style coating is 10 mol%, resistivity maximum 4.07×1011Ω·m, minimum dielectric constant is 222.7, tthe breakdown voltage and breakdown field strength of 3.8V and 8.6 kV/mm, dielectric loss minimum of 0.0038. Therefore, MgO style coated nanometer SrTiO3 matrix composite ceramics reached the fine grains, reduce the degree of reunion, improve the performance of electrical purposes.