Abstract
The effect of MNb2O6 (M=Ni, Zn) columbite ceramics and CuO-V2O5 sintering agent on the microwave dielectric properties of BiNbO4 ceramics was investigated as a function of sintering temperature and composition. The CuO-V2O5 additive effectively lowered the sintering temperature of BiNbO4-MNb2O6 ceramics to ~850oC. From the XRD analysis, a mixture of two phases of orthorhombic BiNbO4 and columbite MNb2O6 was detected. With an increase of MNb2O6, the dielectric constant and the temperature coefficient of resonant frequency (TCF) changed in accordance with the density and dielectric mixing rule, and quality factor (QF) increased up to 10 mol% NiNb2O6 and 10 mol% ZnNb2O6, respectively and then decreased for further addition. The QF change was resulted from the enhanced microstructure of the mixture system. The dielectric constant 40.5, QF 28117 GHz and TCF 4.6 ppm/oC were obtained for the 0.9BiNbO4-0.1ZnNb2O6 ceramics with 1.2 wt% CuO-V2O5 sintered at 850oC for 3 h.
