A co-precipitation route to produce BaTiO3 nanopowders with high tetragonality for ultra-thin MLCCs application

Abstract

Highly tetragonal BaTiO₃ nanopowder serves as a pivotal raw material for manufacturing high-performance miniaturized multilayer ceramic capacitors (MLCCs). In this study, barium acetate and tetrabutyl titanate were used as reactants, isopropanol served as the titanium source stabilizer and dispersant, and oxalic acid was employed as the precipitant to investigate the preparation process of tetragonal-phase BaTiO₃ nanopowder. The optimal process parameters were identified, and the reaction mechanism for synthesizing BaTiO₃ via oxalate co-precipitation was explored. The experimental results indicate that, with a Ba/Ti stoichiometric ratio of 1.000 and a solution pH of 2.33, following the appropriate sequence of experimental reagent additions, the precursor underwent a precipitation reaction at 25 °C. After calcination at 950 °C, BaTiO₃ powder with an average particle size of 56 nm and a tetragonality of 1.0075 was successfully synthesized. The BaTiO₃ ceramic sintered at 1250 °C exhibits a density of 96.5% and an exceptional dielectric performance, with a dielectric constant of 9369 at the Curie temperature (125 °C). This study provides valuable insights for addressing the complex hydrolysis and residual chloride ion issues associated with the chloride method.