Low fire BiNbO4 microwave dielectric ceramics modified by Sm2O3 addition

Abstract The effects of Sm 2 O 3 addition on the microstructure and the microwave dielectric properties of BiNbO 4 ceramics have been investigated. The phase transition temperature (from orthorhombic to triclinic phases) of BiNbO 4 ceramics can be lowered with Sm 2 O 3 addition. It also decreases with increasing Sm 2 O 3 addition. The dielectric constant and the theoretical density are found to increase with increasing sintering temperature, but decrease with increasing Sm 2 O 3 content. The quality factor, Q, is significantly dependent on Sm 2 O 3 substitution, due to many factors, including the microstructure, the phase transition, and the densification. The temperature coefficient of resonant frequency, τ f , is correlated to the phase transition. Bi 0.95 Sm 0.05 NbO 4 ceramics, sintered at 950°C, exhibits the microwave dielectric properties e r ∼44.43, Q × f values ∼ 1800 (at 7.2 GHz), and τ f ∼ −4.2 ppm/°C.