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

The dielectric properties of (Ba0:6Sr0:4)(Ti1 xSnx )O3 (0 x 0:3) ceramics were investigated. Single-phase specimens having a cubic perovskite structure could be obtained. As Sn concentration increased, dielectric loss decreased untill a composition of x 1⁄4 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 0.1mol in (Ba0:6Sr0:4)TiO3 at 1400 C, the dielectric constant, dielectric loss, tunability, Curie point, and figure of merit (FOM) were 1400, 0.0027, 18%, 40 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. # 2009 The Japan Society of Applied Physics