Characterization and dielectric behavior of V2O5-doped MgTiO3–CaTiO3 ceramic system at microwave frequency

The microwave dielectric properties and the microstructures of MgTiO3–CaTiO3 ceramics, prepared by a mixed oxide route, have been investigated. With a small amount of V2O5 addition, the firing temperatures of 0.95MgTiO3–0.05CaTiO3 ceramics can be lowered to 1250 °C. Moreover, it also effectively holds back the formation of second phase MgTi2O5. The microwave dielectric properties are found to strongly correlate with the sintering temperature as well as the amount of V2O5 addition. The Q × f value of 0.95MgTiO3–0.05CaTiO3 increased with increasing temperature to 1300 °C and decreased thereafter. The decrease in Q × f value was coincident with the abnormal grain growth. A maximum quality factor Q × f of 69,000 GHz (where f = 7 GHz, is the resonant frequency) associated with an ɛr of 18.9 and a τf value of −10.65 ppm/°C, was achieved for 0.25 wt% V2O5-doped samples at 1300 °C, although the dielectric properties varied with the amount of V2O5. By appropriately adjusting the x value in the (1 − x)MgTiO3–xCaTiO3 ceramic system, zero τf value can be obtained.