Sintering behavior and microwave dielectric properties of Ca1-xBixW1-xVxO4 ceramics

Structure, sintering behavior and microwave dielectric properties of ceramics have been investigated by x-ray powder diffraction (XRD) and scanning electron microscopy (SEM) in this paper. The microwave dielectric properties of the ceramics were studied with a network analyzer at the frequency of about 6-11 GHz. The sintering temperature and microwave dielectric properties could be successfully tuned in a wide window simultaneously by adjusting the A-O bond characteristics. The sintering temperature of CaWO4 was successfully reduced from 1100 °C to about 950 °C by BiVO4 addition. Approximately 95%-96% theoretical density could be obtained after sintering at 950 °C for 2 h. All samples exhibit single Scheelite structure (I41/a) phase. The dielectric constant increased, whereas the Q×f value decreased, with the increase of x. The τf value changed from negative to positive with the increases of x. Combined excellent microwave dielectric properties with εr=22. 1, Q×f=16,730 GHz and τf=2.39 ppm/°C could be obtained after sintered at the 950 °C for 2 h for x=0.3 compositions.