Microwave dielectric characteristics of 0.75(Al1/2Ta1/2)O2–0.25(Ti1−xSnx)O2 ceramics

The microwave dielectric characteristics of 0.75(Al1/2Ta1/2)O2–0.25(Ti1−xSnx)O2 ceramics were investigated. The microwave dielectric properties of 0.75(Al1/2Ta1/2)O2–0.25TiO2 sintered at 1450 °C exhibited a dielectric constant (ϵr) of 31.2, a Q·f0 of 54,590 GHz, and the temperature coefficient of resonant frequency (τf) of +12.8 ppm/°C. To control of the τf and enhance the Q·f0 for 0.75(Al1/2Ta1/2)O2–0.25TiO2, Sn4+ was substituted for Ti4+. With an increase of Sn content from 5 to 50 mol%, the εr slightly decreased, the Q·f0 increased and the τf shifted from positive to negative value. The τf within ±10 ppm/°C of zero was realized for the Sn content below 30 mol% and the microwave dielectric properties had the εr value of 31.2–26.3, the Q·f0 of 54,600–70,700 GHz, and τf of +12.8–−9.3 ppm/°C for this compositions. The relationship between microstructure and microwave dielectric characteristics was investigated.