Effects of Ta2O5 on microwave dielectric properties of BiNbO4 ceramics

Effects of Ta substitution for Nb on the microwave dielectric properties of BiNbO4 ceramics have been investigated. BiNb(1−x)TaxO4 (x=0, 0.1, 0.2, 0.3, 0.4) with 0.3 wt.% CuO–V2O5 mixtures addition can be densified at very low sintering temperature below 860 °C. The dielectric constants (εr) of the Ta-modified BiNbO4 ceramics increase with increasing of Ta contents, but the Q×f values have no apparent changes. The temperature coefficient of resonant frequency (τf) changes from positive to negative with change of x values. The crystalline phase and microstructure of Ta-modified BiNbO4 ceramics have been characterized by X-ray diffraction and scanning electron microscopy respectively.