Effect of Cu2+ substitution on phase composition, microstructure, and microwave dielectric properties of Mg1-xCuxSiO3 ceramics

Solid-state sintering method was used for the synthesis of Mg1-xCuxSiO3 (x = 0-0.06) ceramics.The phase, microstructure and microwave dielectric properties of ceramics were studied.MgSiO3 exists in polycrystalline form and is composed of orthorhombic MgSiO3 as the main phase, SiO2 and monoclinic MgSiO3 as the secondary phase. The existence of the secondary phase will deteriorate the sintering characteristics and dielectric properties. Appropriate Cu2+ substitution can effectively eliminate SiO2 phase at relatively low temperature, and inhibit the formation of monoclinic MgSiO3 phase. The substitution of Cu2+ improves the sintering properties of MgSiO3 ceramic significantly, the maximum relative density increased from 92.3% at x = 0 to 96.58% at x = 0.02, and the sintering temperature decreased by 50 degrees C. With the increase of Cu2+ content, the lattice parameters also increase. Dielectric constant is mainly affected by density and intrinsic polarizability, and Q x f is influenced by the microstructure, density and secondary phase content. When the x content increases from 0 to 0.02, the Q x f value of Mg1-xCuxSiO3 increases from 27,378 GHz to 87,283 GHz. The resonant frequency temperature coefficient of the ceramic is also corrected. For x = 0.02 composition (Mg0.98Cu0.02SiO3) sintered at 1420 degrees C for 3 h, good dielectric properties were obtained at 13.565 GHz:( epsilon(r) = 6.58, Q x f = 87,283 GHz and tau(f) = - 11.8 ppm/degrees C). Due to its low dielectric constant and excellent quality factor, it is very suitable for high-frequency communication applications.