Characterization and dielectric behavior of V2O5-doped 0.9Mg0.95Co0.05TiO3–0.1Ca0.6La0.8/3TiO3 ceramic system at microwave frequency

The microwave dielectric properties and the microstructures of Mg0.95Co0.05TiO3–Ca0.6La0.8/3TiO3 ceramics, prepared by a mixed oxide route, have been investigated. With small amount of V2O5 additions, the sintering temperatures of 0.9Mg0.95Co0.05TiO3–0.1Ca0.6La0.8/3TiO3 ceramics can be lowered to 1250 °C. The microwave dielectric properties are found strongly correlated with the sintering temperature as well as the amount of V2O5 additions. The Q × f value of 0.9Mg0.95Co0.05TiO3–0.1Ca0.6La0.8/3TiO3 increased with increasing temperature to 1250 °C and decreased thereafter. The decrease in Q × f value was coincident with the abnormal grain growth. A maximum Q × f value of 58,000 (GHz) associated with a dielectric constant (ɛr) of 21.7 and a temperature coefficient (τf) of −10 ppm/°C, was achieved for 0.25 wt.% V2O5-doped samples at 1250 °C. Moreover, a cross-coupled compact hairpin filter with designed center frequency of 2.0 GHz is designed and fabricated using the proposed dielectric ceramic to study its performance. It also showed a substantial reduction in both insertion loss and size in comparison with other dielectrics FR4 and alumina.