Characterization and dielectric behavior of V 2O 5-doped 0.9Mg 0.95Co 0.05TiO 3–0.1Ca 0.6La 0.8/3TiO 3 ceramic system at microwave frequency

Abstract

The microwave dielectric properties and the microstructures of Mg 0.95Co 0.05TiO 3–Ca 0.6La 0.8/3TiO 3 ceramics, prepared by a mixed oxide route, have been investigated. With small amount of V 2O 5 additions, the sintering temperatures of 0.9Mg 0.95Co 0.05TiO 3–0.1Ca 0.6La 0.8/3TiO 3 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 V 2O 5 additions. The Q × f value of 0.9Mg 0.95Co 0.05TiO 3–0.1Ca 0.6La 0.8/3TiO 3 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 ( ɛ r) of 21.7 and a temperature coefficient ( τ f ) of −10 ppm/°C, was achieved for 0.25 wt.% V 2O 5-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.