Phase Transition and Physical Characteristics of Nanograined BaTiO ₃ Ceramics Synthesized from Surface‐Coated Nanopowders

Abstract

Nanograined BaTiO 3 ceramics prepared from 40‐nm‐size BaTiO 3 nanopowders exhibited the cubic as well as the tetragonal phase, while nanograined BaTiO 3 ceramics prepared from BaTiO 3 nanopowders coated with Mn had only the tetragonal phase. The dielectric constant of the latter was 10 times larger than that of the former; the latter exhibited PTCR behavior with a resistivity jump ratio of about 5.0 × 10 4 . These physical properties of the BaTiO 3 ceramics appeared to be significantly affected by the strain near grain boundaries; such strain resulted in a phase transition from the cubic to the tetragonal phase in the nanograined BaTiO 3 ceramics, even though the grain size was about 40 nm.