Calcium-doping for enhanced temperature stability of (Ba0.6Sr0.4)1−xCaxTiO3 thin film dielectric properties

Ternary (Ba_0.6Sr_0.4)_1−xCa_xTiO₃ (BSCT) (x = 0, 0.1, 0.2, 0.3 and 0.4) thin films with thickness of around 500 nm were prepared on Pt(111)/TiO₂/SiO₂/Si substrates by sol-gel methods. BSCT forms the complete solid solutions in a single cubic perovskite structure. The lattice constant, dielectric constant, tanδ and tunability of BSCT decrease, whereas the temperature stability of dielectric properties increases with increasing the Ca concentration. From 25 to 100 °C, the decrease of tunability is about 11% for BSCT with 40 at.% of Ca. BSCT thin films exhibit the comparable tunability, low loss and enhanced temperature stability.