Abstract
Synthesis of fine BaTiO3 powder through mechanochemically prepared precursors has been investigated. The precursors were prepared from Ba(OH)2·8H2O and TiO2 by wet planetary mill treatment using acetone as a liquid medium. Pseudo-cubic BaTiO3 was obtained after heat treatment of the precursors at 700°C for 3h. Anatase, rutile, Ba6Ti17O40 and other titanates did not form during thermal treatment. The BaTiO3 powder were sintered to densities more than 94% of the theoretical at 1250°C for 1h. The sintered materials showed a homogeneous microstructure consisting of fine grains less than 1μm, which was close to the optimum grain size for BaTiO3 having a high dielectric constant. The well-mixed composite precursors consisting of Ba(OH)2·xH2O and hydrous TiO2 were synthesized by the following successive processes; (1) extraction of hydrated water into the liquid media, (2) mechanochemical hyration of TiO2, and (3) alloying of dehydrated Ba(OH)2·xH2O and hydrated TiO2, for example TiO2·H2O and TiO(OH)2, although the reactions were not completed.
