Influence of molybdenum substitution on the microwave dielectric properties of CaWO 4 ceramic

Dielectric properties of Ca(W1−xMox)4 (x = 0, 0.02, 0.04, 0.06, 0.08) were investigated at microwave frequency. With the increase of MoO3, the dielectric constant (ε r ) increased slightly, the value of quality factor (Q × f 0) increased considerably and reach the maximum of 79,919 GHz, and the temperature coefficient of resonant frequency (τ f) shifted for the minus direction. The relationship between the dielectric properties and polarizability, packing fraction and the oxygen bond valence were discussed. The optimum results were obtained when x = 0.06, the dielectric properties are as follows: ε r  = 10.22, Q × f 0 = 79,919 GHz and τ f = −40.39 ppm/°C.