Formation of Core‐Shell Structure in the BaTiO 3 ‐SrTiO 3 System

When a 1‐mol%‐Fe 2 O 3 ‐added 0.67BaTiO 3 ‐0.33SrTiO 3 (mole ratio) powder compact was sintered at 1380°C, a core‐shell structure was developed. The core phase formed via solid‐state interdiffusion of barium and strontium ions between BaTiO 3 and SrTiO 3 particles. In contrast, the shell phase formed via a solution‐precipitation process in the presence of an Fe 2 O 3 ‐containing liquid phase. Energy‐dispersive X‐ray analysis showed that the core was a strontium‐rich paraelectric phase and the shell was a barium‐rich ferroelectric phase at room temperature. The core‐shell structure developed in the BaTiO 3 ‐SrTiO 3 system suggests the possibility of obtaining a variety of phase distributions with different Curie temperatures.