Synthesis of fine Ca-doped BaTiO{sub}3 powders by solid-state reaction method - Part I: Mechanical activation of starting materials

摘要

Fine (Ba{sub}0.9gCa{sub}0.02){sub}1.002O{sub}3 powders for high capacitance multilayer ceramic capacitors (MLCCs) application were synthesized by solid state reaction method. The effects of mechanochemical activation using high energy milling and the starting materials properties on the reaction temperature and on the final powder properties were investigated. Previous heavy milling of BaCO{sub}3 and the adoption of fine, anatase-rich TiO{sub}2 phase were effective in decreasing the reaction temperature and in increasing the tetragonality (=c/a). BaCaTiO{sub}3 powders with a tetragonality of 1.0097, an average particle size of 213 ±43 nm and a specific surface area of 6.30 m{sup}2/s were acquired after heat treatment at 985℃ for 2 h. MLCCs utilizing this developed powder showed superior dielectric and temperature characteristics to those with conventional, Ca-free BaTiO{sub}3 powder.