Two novel A4B3O12-type microwave ceramics with high-Q and near-zero τf

Two novel La3+ and Ti4+ cosubstituted Sr3LaNb3O12 ceramics, Sr2La2TiNb2O12 and SrLa3Ti2NbO12, were prepared and the effect of substitution on the microwave dielectric properties was investigated. Results showed that as the amounts of substitution increased, dielectric constant (εr) increased from 36 to 41, and temperature coefficient of resonant frequency (τf) improved from −9 to 3 ppm/°C, whereas the quality factor (Q×f) decreased from 45,000 to 33,600 GHz. A temperature-stable microwave dielectric ceramics SrLa3Ti2NbO12 with τf of 3 ppm/°C, εr of 41, Q×f of 33,600 GHz was obtained; it might be a promising candidate for practical application in base stations if the quality factor is enhanced beyond 40,000 GHz.