Microwave dielectric properties of BaO–Ta2O5–TiO2 system

Microwave dielectric properties of the BaO–Ta2O5–TiO2 system were investigated by the solid-state reaction method. It was recognized that the Ba10Ta7.04(Ti1.2 − xSnx)O30 solid solutions have the higher Q · f value in comparison with the Ba8(Ta4 − xNbx)Ti3O24 solid solutions. The limit of the Ba10Ta7.04(Ti1.2 − xSnx)O30 solid solutions was approximately x = 0.75; the lattice parameter c of the solid solutions, which is related to the change in the B(1)O6 octahedron, was significantly increased in the composition range from 0 to 0.75. The Q · f values of the Ba10Ta7.04(Ti1.2 − xSnx)O30 solid solutions are remarkably improved by the Sn substitution for Ti; the highest Q · f value of 59,100 GHz is obtained at x = 0.75. Moreover, the ɛr and τf values of the Ba10Ta7.04(Ti1.2 − xSnx)O30 solid solutions at x = 0.75 were 25.6 and 30.3 ppm/°C, respectively.