Preparation, Characterization And Capability Of Nanometer-sized BaTiO₃ Powders Adulterated By Soft Chemistry

Electronic ceramic material is an important field in material science, which is applied to semiconductor, piezoelectricity, dielectric material and insulation material. BaTiO3 as a kind of very important dielectric material, has been widely applied in the production of electric components such as high-property ceramic capacitor, multilayer ceramic capacitor, PTC heat-sensitive resistance, resonance implement, medium amplifier, and is indispensable in electronic industry. Its dosage is largest as capacitor material and basic matrix of electric function ceramic at present. In order to meet the high-capacity need of dielectric material, preparing symmetrical and little-size nanometer powder is the sticking point. In my research work, firstly synthesis methods of pure BaTiO3 were probed to obtain excellent crafts of powder preparation. Nanometer-sized BaTiO3 powders were prepared with inorganic salt, such as TiCl4,Ba(OH)2, as raw material by nomal pressure liquid-phase method, water-thermal method and microwave liquid-phase method respectively. Powders synthesized by these three methods were characterized. XRD analysis showed that the powders were cubic provskite structure. The powders are less aggregation and symmetrically ball-like through TEM analysis. The powders synthesized by water-thermal method are larger than those of the other two methods. The size and shape of powders synthesized by microwave method is excellent. Through changing the conditions of reactive system, such as reactant concentration, hydrolysis time, reactant time, material match, the best crafts parameters were obtained, which can prepared small-sized and evenly scattered nanometer BaTiO3 powder. The powders synthesized by the three methods were sintered to ceramic, and mesurate their capability. Because microwave irradiation can synthesize nanometer-sized and evenly scattered powders, the ceramic sintered with them has the better capacity. From the experiment, the relationship of capacity and grain size is determined. But because of the structure of BaTiO3 molecule, it has some shortcoming. For example, it has the highest dielectric constant at 120 ℃(~ 104), while its dielectric constant at room temperature is only 1 / 6 of the Curie point, which greatly limited its practical applications.