Dielectric properties and tunability of (Ba _1-xSr _x)TiO ₃:MgO composites

Composites of ferroelectric (Ba _1-xSr _x)TiO ₃ (BST) and non-ferroelectric MgO were prepared using nano particles to study the dielectric properties for microwave applications. By using precursor compounds of nano-sized particle, considerable reduction in dielectric losses was obtained, which enhances the figure of merit, K-factor, in the resulted composites. (Ba _1-xSr _x)TiO ₃:MgO composites with various volume ratios of the two components were sintered in a temperature range from 1400°C to 1600°C. Dielectric properties were studied in the temperature range of-250°C to 100°C, with and without bias electric fields. The low dielectric constants and tangent losses combined with high tunability and K-factor were achieved in the resulted composites. Tunable dielectric properties in relation to microstructure of BST:MgO composites are also discussed.