Effect of Co²⁺ substitution on sintering behavior and microwave dielectric properties of Ca(Mg_0.92−xCo_xAl_0.08)(Si_0.96Al_0.04)₂O₆ ceramics

Abstract

In this study, the effects of Co²⁺ substitution for Mg²⁺ on the sintering behavior and dielectric properties of Ca(Mg_0.92−xCo_xAl_0.08)(Si_0.96Al_0.04)₂O₆ ceramics were investigated. The main phase transformed from Ca(Mg,Co,Al)(Si,Al)₂O₆ to CaCoSi₂O₆ as the x value varied from 0.1 to 0.92. Meanwhile, the sintering temperature decreased from 1250°C (x = 0.1) to 1150°C (x = 0.8 and x = 0.92), and both the dielectric constant and the τ_f value increased with the increase of the x value. Typically, the coexistence of the two phases resulted in a relatively porous structure that lowered the Q×f value of the ceramic system when the x value was 0.4 and 0.5. Sintered at the temperature of 1150°C, a Q×f value of 60,125 GHz with dielectric constant of 8.46 and τ_f value of −49.26 ppm/°C was obtained for the Ca(Mg_0.92−xCo_xAl_0.08)(Si_0.96Al_0.04)₂O₆ ceramics with the x value of 0.92.