Effects of Ca Addition on Chemical Composition, Microstructure and Dielectric Properties of BaTiO₃

Abstract

Owing to its high dielectric constant, barium titanate is a material commonly employed in fabrication of high energy density capacitors. Dielectric properties required for practical applications can be attained in barium titanate with desired chemical composition and microstructure. This study, therefore, aims at examining effects of additive contents on formation of secondary phases, microstructure and dielectric properties of BaTiO3 and BaTiO3 with 20-40 at% Ca. Chemical composition analysis revealed that single-phase BaTiO3 powder could be attained by the solution combustion technique. However, the powder with high Ca content exhibited large quantities of secondary phases. Dielectric property measurements of the uniaxially pressed powders indicated that dielectric constants could be enhanced with low Ca content. On the contrary, dielectric constant significantly degraded with high Ca content. This was attributed to formation of large quantities of secondary phases, coarse grain size and low density. Values of dielectric loss of all materials were lower than 1%.

Recent development on modification of synthesized barium titanate (BaTiO3) and polymer/BaTiO3 dielectric composites

“…[64][65] When the grain size of BaTiO3 particles further decreases to micron level, the relative dielectric constant firstly increases and then decreases. [66] In Figure 6, it is observed that with the decrease of grain size, the dielectric constant of BaTiO3 particles decreases remarkably. The reason is that with the decrease of grain size, the fraction of cubic layer on particle surface increases, resulting in the decrease of tetragonal phase and ferroelectricity of BaTiO3 particles.…”