Effect of Bi2O3 Doping on the Sintering Temperature and Microwave Dielectric Properties of LiAlSiO4 Ceramics

When Bi2O3 was added to LiAlSiO4 ceramics, Bi12SiO20 secondary phase was formed. Since the melting temperature of Bi12SiO20 ceramics is 880°C, the liquid phase is expected to form during sintering and to assist the densification of LiAlSiO4 ceramics. When 15.0 mol% Bi2O3 was added, the LiAlSiO4 ceramics could be sintered at 900°C, and with 20.0 mol% Bi2O3 they could even be sintered at 875°C. The 15.0 mol% Bi2O3-doped LiAlSiO4 ceramics sintered at 900°C exhibited good microwave dielectric properties, namely, a low er of 4.3, a high Q × f of 62 430 GHz and a small τf of −16.21 ppm/oC.