Although nano-sized barium titanate powder (BaTiO3) with a high tetragonality (large c/a) is essential to enhance the volumetric efficiency of multi-layer ceramic capacitors (MLCCs) in industry, the tetragoanlity diminishes with a decrease in particle size and disappears below a critical particle size. Many researchers have investigated an understanding of the relationship between particle size and the tetragonality of BaTiO3 and tried to increase this value while maintaining the particle size as small as possible. Recent experimental results, including ours, on critical particle sizes and their tetragonality values of fine BaTiO3 powders are reviewed in this paper.

Keywords: dielectric properties; BaTiO3; capacitors; tetragonality