Microwave Dielectric Properties of Low Temperature Firing Bi 2 Mo 2 O 9 Ceramic

Preparation, phase stability, sintering behavior, microwave dielectric properties of single‐phase Bi 2 Mo 2 O 9 ceramic and its chemical compatibility with Ag have been investigated. The single‐phase Bi 2 Mo 2 O 9 ceramic can be well densified in the temperature range from 620° to 645°C with relative density about 96%. X‐ray diffraction data show that Bi 2 Mo 2 O 9 has a monoclinic structure ( P 2 1 / n ), with lattice parameters a =11.9664 Å, b =10.8089 Å, and c =11.8871 Å. When sintering temperature ≥650°C, Bi 2 Mo 3 O 12 appears as a secondary phase. Pure monoclinic Bi 2 Mo 2 O 9 ceramic sintered at 620°C for 2 h exhibits good microwave dielectric properties with permittivity about 38, Q f value about 12 500 GHz and temperature coefficient of resonant frequency about +31ppm/°C. The permittivity of single‐phase Bi 2 Mo 2 O 9 corrected for porosity is about 40.17. However, the reaction between Bi 2 Mo 2 O 9 and Ag will affect its further application in low‐temperature cofired ceramic.