Property optimization of Ba0.4Sr0.6TiO3–BaMoO4 composite ceramics for tunable microwave applications

(1 − x)Ba0.4Sr0.6TiO3–xBaMoO4 ceramics with x = 5, 10, 20, 30, 40 and 60 wt% were prepared by traditional solid-state reaction method. Two crystalline phases, a cubic perovskite structure Ba0.4Sr0.6TiO3 (BST) and a tetragonal scheelite structure BaMoO4 (BM) were obtained by XRD analysis. The microwave dielectric properties of Ba0.4Sr0.6TiO3–BaMoO4 composite ceramics were investigated systematically. The results show that the composite ceramics exhibited promising microwave properties. The dielectric constant can be adjusted in the range from 900 to 78, while maintaining relatively high tunability from 27.3% to 12.8% under a direct current electric field of 60 kV/cm and Q values from 619 to 67 in the gigahertz frequency region.