Improved Figure of Merit of (Ba,Sr)TiO3-Based Ceramics by Sn Substitution

Abstract

The dielectric properties of (Ba0.6Sr0.4)(Ti1-xSnx)O-3 (0 <= x <= 0.3) ceramics were investigated. Single-phase specimens having a cubic perovskite structure could be obtained. As Sri concentration increased, dielectric loss decreased untill a composition of x = 0.15 and slightly increased as Sn concentration increased further. The diffused phase transition appeared owing to substitution of Sn ions. When Sn was substituted at 0.1 mol in (Ba0.6Sr0.4)TiO3 at 1400 degrees C, the dielectric constant, dielectric loss, tunability, Curie point, and figure of merit (FOM) were 1400, 0.0027, 18%, -40 degrees C, and 67, respectively. These compositions show excellent dielectric properties than those of (Ba0.5Sr0.5)TiO3 ferroelectrics, which are limelight materials for tunable devices such as varactors, phase shifters, and frequency agile filters. (c). 2009 The Japan Society of Applied Physics