Characterization and dielectric behavior of V₂O₅-doped 0.9Mg_0.95Co_0.05TiO₃-0.1Ca_0.6 La_0.8/3TiO₃ ceramic system at microwave frequency

The microwave dielectric properties and the microstructures of Mg_0.95Co_0.05TiO₃-Ca_0.6La _0.8/3TiO₃ ceramics, prepared by a mixed oxide route, have been investigated. With small amount of V₂O₅ additions, the sintering temperatures of 0.9Mg_0.95Co_0.05TiO₃-0.1Ca_0.6 La_0.8/3TiO₃ 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 0.9Mg_0.95Co_0.05TiO₃-0.1Ca_0.6 La_0.8/3TiO₃ 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 (ε_r) of 21.7 and a temperature coefficient (τ_f) 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. Crown