( Institute of Materials Science and Engineering,Wuhan University of Technology, 430070)

Abstract：( 1 -y)Ca1-xLa2x/3TiO3 -yCa( Mg1/3Nb2/3)O3 microwave dielectric ceramics were prepared by solid state reaction tech- nique and the microwaev dielectric properties and microstructure were also investigated .The results show that a single per- ovskite structure formed within investigated composition range .The microwave properties of complex system largely depend on the composition .When x =0 .4, y =0 .5, ( 1 -y) Ca1-xLa2x/ 3TiO3 -yCa( Mg1/3Nb2/3) O3 ceramics obtained at 1400 ℃for 4h exhibit excellent microwave dielectric properties :dielectric constant εr =55, Q ×f =45000GHz( at 7 .6GHz) , temperature coef- ficient of resonant frequency τf =0 .04ppm/ ℃.

Keywords：complex perovskite, microwave dielectric ceramics, dielectric properties