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

Two novel La 3+ and Ti 4+ cosubstituted Sr 3 LaNb 3 O 12 ceramics, Sr 2 La 2 TiNb 2 O 12 and SrLa 3 Ti 2 NbO 12 , 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 (e r ) increased from 36 to 41, and temperature coefficient of resonant frequency (τ f ) 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 SrLa 3 Ti 2 NbO 12 with τ f of 3 ppm/°C, e r 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.