Spark-plasma-sintering of fine BaTiO3 powder prepared by a sol-crystal method

Spark-Plasma-Sintering (SPS) has been applied to fine BaTiO3 powder (severa l nanometers) prepared by a sol-crystal method. The starting powder was den sified to more than 95% of the theoretical X-ray density, and the obtained SPS pellets had an average grain size of less than 1 mum, owning to the rel atively low sintering temperature (900-1000 degreesC) and short sintering p eriod of ca. 3 min. The room temperature permittivity at 1 kHz for SPS samp les sintered at 1000 degreesC is ca. 10,000. This high room temperature per mittivity value is attributed to electrical inhomogeneities within pellets; a resistive surface layer covers the inner pellet core that consists of ox ygen-deficient BaTiO3. The reduced pellet core is characteristic of SPS pel lets formed from powders that contain small amounts of residual organic mat ter. (C) 2001 Kluwer Academic Publishers.