Effect of microwave and conventional sintering on densification, microstructure and dielectric properties of BZT–xCr2O3 ceramics

Barium zinc tantalate (BZT) ceramics with high density and uniform microstructure is a potential material for application as microwave window sections in fusion reactor. In the present investigation the effect of Cr2O3 addition on the densification, microstructure development and microwave dielectric properties of BZT has been studied. 97% of the theoretical density has been achieved for BZT–2 mol% Cr2O3 in microwave sintering only at 1400 °C. Irregular grains with diffused grain boundaries have been observed for the samples sintered at 1400 °C. Anisotropic grain growth has been observed with increase in sintering temperature. A maximum Quality factor (Qxf) of 98,000 GHz is obtained for samples containing 0.5 mol% Cr2O3 after annealing. 1:2 ordering of the B-site ions is more predominant for pure BZT compared to samples containing Cr2O3, as analyzed from Raman spectroscopic data, which is in accordance with the order parameter calculated from the XRD data.