Particle sizes effects on electrical properties and densification of laminated Ba1.002La0.003TiO3 ceramics

This paper investigated the influences of initial particle sizes on electrical properties and densification of laminated Ba1.002La0.003TiO3 ceramics prepared by the reduction-reoxidation technique. Ba1.002La0.003TiO3 powders with average size of∼820 nm and∼260 nm were prepared by the planet ball milling and the sand milling, respectively. For ceramic samples from ∼260 nm particles, the inflection point where the densification rate begins to decrease occurs at a higher sintering temperature than that of ceramic samples from∼820 nm particles. An abnormal growth of grains is observed in ceramic samples from∼820 nm particles, which resists reoxidation. Samples from∼260 nm particles are prone to be globally reoxidized and exhibit a much greater change in grain boundary resistance and RT resistivity after reoxidation. A possible mechanism of the oxygen diffusion in the reoxidation process is proposed, which verifies that samples with smaller grains as well as lower density are easily oxidized to a deeper degree.