Tetragonality of nano-sized barium titanate powder prepared with growth inhibitors upon heat treatment

摘要

Nano-sized barium titanate powders with high dielectric constant are preferred for many reasons in industry, while it is generally known that the dielectric constant is decreasing with the decrease in particle size. In order to enhance the dielectric constant of fine hydrothermal BaTiO_3 powders by eliminating the internal defects, heat treatment at various temperatures is performed. The behavior of tetragonality, an indirect measure of dielectric constant, is investigated as a function of particle size and heat treatment temperature. Growth inhibitors such as carbon black and corn starch are added to minimize the drawbacks of heat treatment such as hard agglomeration and particle growth. Controlling the particle size is possible by using inhibitors, but the efficiency of tetragonality enhancement by heat treatment is relatively low. Explanations for these results are included.