Figure 4 (b) represents the effect of the sintering temperature on densification, relative permittivity (ɛr), quality factor (Qf) and FWHM of the selected A1g mode (high intensity as compared to other A1g modes in the spectrum). The sintering experiments revealed that the densification increased to a maximum when sintered at 650 oC and after that showed a slight decrease, this being in line with the microstructural studies. Also, the relative permittivity and Qf of bulk MoO3 ceramics increased from 5.6 to 6.6 and from 24,000 to 41,000 GHz at 11.3 GHz, respectively, when the sintering temperature was increased from 550 oC to 650 oC. At the higher temperature of 700 oC, the densification, relative permittivity and Qf of the sample degraded. The porosity corrected relative permittivity of this ceramic was found to be 8 using equation 2 with a theoretical model for high porosity samples by the modified Bruggeman method [28].