HIGH ELECTRIC FIELD INDUCED STRAIN IN SOLID-STATE ROUTE PROCESSED BARIUM TITANATE CERAMICS

Barium titanate (BaTiO3) was prepared by a solid state route from highly pure raw materials. Homogenization by attrition milling resulted in fine grained powders, which could be calcined to single phase BaTiO3 at 875 degrees C and sintered to high density ceramics at 1200-1250 degrees C. Due to the relatively low sintering temperatures, grain size remains in the range below 2 mu m. The material shows very good performance under 2kV/mm electric high field cycling with 0.12% strain at ambient conditions. Field dependence of strain at 20 degrees C shows moderate strain under subcoercive field conditions, high strain in the intermediate field range up to 2 kV/mm and saturation resulting in to low additional strain at higher fields. The temperature characteristics of the strain reveal a marked decrease by approximately one third when increasing the temperature to 60 degrees C. At higher temperatures field induced strain stabilizes when approaching the Curie temperature. From the nonlinearity characteristics at ambient conditions and the temperature behavior, it is concluded that contributions from reversible domain switching to strain are a major source of the high strain performance.