Microstructures and Microwave Dielectric Properties of Bi ₂ O ₃ ‐Deficient Bi ₁₂ SiO ₂₀ Ceramics

Abstract

The Microstructure and microwave dielectric properties of Bi 2 O 3 ‐deficient Bi 12 SiO 20 ceramics were investigated. A small amount of unreacted Bi 2 O 3 phase melted during sintering at 825°C and assisted with densification and grain growth in all samples. The melted Bi 2 O 3 reacted with remnant SiO 2 during cooling to form a Bi 4 Si 3 O 12 secondary phase. The nominal composition of Bi 11.8 SiO 19.7 ceramics sintered at 825°C for 4 h had a high relative density of 97% of the theoretical density, and good microwave dielectric properties: ε r = 39, Q × f = 74 000 GHz, and τ f = −14.1 ppm/°C. Moreover, this ceramic did not react with Ag at 825°C.