Microwave Dielectric Properties of Sol-Gel Processed Bi₄Si₃O₁₂ Ceramics and Single Crystal

Microwave dielectric ceramics Bi₄Si₃O₁₂ was made from powders prepared via sol-gel method as a potential candidate of low temperature co-fired ceramics in microwave applications. The microwave dielectric properties of sol-gel processed Bi₄Si₃O₁₂ ceramics were compared with that of single crystal. The sintering temperature of the ceramics ranged from 920° to 1010°C. The best microwave dielectric properties were obtained when the ceramics was sintered at 980°C for 8 h with a permittivity of ∼8.8, a Q×f value of ∼41,898 GHz (at 11.5 GHz) and a temperature coefficient value of –72 ppm/°C. The permittivity, Q×f value, and temperature coefficient value of Bi₄Si₃O₁₂ single crystal were ∼15.9, 45,326 GHz (at 7.0 GHz) and –92 ppm/°C, respectively.