Microwave dielectric properties and sintering behaviors of scheelite compound CaMoO4

The microwave dielectric properties, sintering behaviors of scheelite compound CaMoO4 were investigated using dilatometry, X-ray diffraction, scanning electron microscopy and network analyzer. To improve the sintering property of CaMoO4, samples with different Ca/Mo ratio were prepared. The bulk densities of CaMo(x)O4 (for x = 1.02, 1.05, 1.08) samples were higher than those of pure CaMoO4 over all temperature range. The well-sintered CaMo(x)O4 (for x = 1.02) sample with ∼95.7% of the theoretical density shows Q × f value of 71,000 GHz and dielectric constant (ɛr) = 10.3. The effects of liquid phase formation on sintering process and dielectric properties were discussed. Sample with hot-press sintering was also prepared in order to investigate dielectric properties of fully dense CaMoO4, which exhibited quality factor (Q × f), ∼55,000 GHz and dielectric constant (ɛr) = 11.7.