Synthesis of barium titanate: Influence of Ba/Ti ratio on the ceramic properties

BaTiO3 is mainly used for multilayer capacitors, due to dielectric constant and low loss characteristics. Higher capacitance in smaller size (200-400 layers approximate to 2mum each) is the present goal. Particles (100-300 nm) with narrow distribution and suitable stoichiometry are needed for correct microstructure and performances. 20-300 nm particles were produced by low-temperature-aqueous-synthesis (LTAS) from Ba(OH)(2) and TiCl4 in NaOH solution (80 degreesC, ambient pressure). Relatively uneasy control of Ba/Ti ratio, related with kinetics of precipitation and decrease of Ba-concentration during synthesis, is the drawback leading to dramatic changes in microstructure. Introduction of Segmented-Flow-Tubular-Reactor (SFTR) technology greatly improves powders quality