SrZn2(PO4)2–TiO2 composite microwave dielectric ceramics with wide tunability range for temperature coefficient of resonant frequency

Abstract

A phosphate based composite ceramics system, (1 − x)SrZn2(PO4)2–xTiO2 (0 ≤ x ≤ 0.5), was prepared by the solid-state reaction method, and the relations between the phase composition, crystal structure and microwave dielectric properties were investigated. The results show that only two phases of SrZn2(PO4)2 and TiO2 can be obtained in the whole range of x value, and high relative density can be archived for all compositions as suitable sintering temperatures were applied. In the variation process of phase composition ratio, lower increase of dielectric constant value (<14) and wide changing range of temperature coefficient of resonant frequency (from −76 to +110 ppm/°C) can be obtained synchronously. When the phase composition ratio x value are 0.5, composite ceramics above possesses microwave dielectric properties as e = 12.011, Q × f = 24900 GHz and τ f = +91 ppm/°C as the sintering temperature was 1000 °C.