Sintering Behavior, Microstructure, and Dielectric Properties of Nano-Ba0.7Sr0.3TiO3 Ceramics

Abstract

Nanoscale Ba0.7Sr0.3TiO3 (BST) powders were synthesized by solid-state reaction, chemical dispersion, and mechanical grinding. Capacitor samples based on the nano-BST powders were then prepared; their sintering behaviors at different temperatures, dielectric properties, and correlations to microstructure were investigated accordingly. It was found that specific sintering conditions are essential for achieving high-density (>= 95%) BST samples with a desired microstructure. Dielectric property measurements revealed that the best result was achieved in samples sintered at 1200 degrees C for 6h (dielectric constant = 9700; dielectric loss = 0.04) or at 1300 degrees C for 1 h (dielectric constant = 9800; dielectric loss = 0.075). The BST samples exhibited a lower Curie point (T-C) than conventional BaTiO3 (BTO) and BST systems. The improvement of dielectric properties and phase transition temperature were attributed to the fine grain structure in BST samples.