Preparation and size effect in pure nanocrystalline barium titanate ceramics

The experimental investigation of the rate-controlled synthesis and sintering of barium titanate by different methods have been carried out. It is shown that the permittivity of barium titanate depends on effective grain boundaries width, which consists of physical grain boundary and depolarization field area. The effective grain boundary width depends on ceramics consolidation methods. The polydomain structure with domain width 10-12 nm is discovered in nanocrystalline barium titanate ceramics with grain size 50-70 nm. The generalized polymorphous phase diagram for pure barium titanate is proposed depending on grain size and temperature.