Compositionally inhomogeneous Ti-excess barium strontium titanate ceramics with a robust dielectric temperature stability

•Compositionally inhomogeneous Ti-excess BST ceramics were synthesized by phase-mixed method.•Little temperature dependence of dielectric constants for Ti-excess BST ceramics is obtained.•The Ti-excess BST ceramics retain a high tunability of more than 25% (10kV/cm).

Compositionally inhomogeneous barium strontium titanate (BST) ceramics with a robust dielectric temperature stability were synthesized by adding excessive TiO2 into phase-mixed powders. Effects of excessive TiO2 on microstructures, dielectric properties and tunabilities of these ceramics were investigated. Results show that the grain size is obviously decreased and the dielectric temperature stability is dramatically improved by adding excessive TiO2. Especially, almost little temperature dependence of dielectric constants for Ti-excess specimens is obtained from 25 °C to 70 °C. Meanwhile, their high tunabilities, more than 25% under the DC electric field of 10 kV/cm, are still retained. Such compositionally inhomogeneous Ti-excess BST ceramics with a weak dielectric temperature sensitivity and high tunability are potential materials for tunable microwave applications.