Microwave dielectric properties of Ca1-xBaxMgSi2O6 ceramics

Ca1-xBaxMgSi2O6(x = 0–0.4) ceramics were prepared through a traditional solid-state reaction sintering route with various sintering temperatures. The effects of substituting Ba2+ for Ca2+, the relative density, phase composition, crystal morphology, and microwave dielectric properties of Ca1-xBaxMgSi2O6 (x = 0–0.4) ceramics were thoroughly studied. X-ray diffraction patterns indicate a single phase was formed in the samples when x ≤ 0.2, and the second phase BaMg2Si2O7 appeared at x = 0.4. As the amount of Ba2+ substitution increases, the Q×f value first increases and then decreases due to the combined effects of FWHM of peak v11 and atomic packing density, and the εr value was increased continuously which was closely corrected with the relative density and molecular polarization. The τf value improved slightly with the substituting Ba2+ for Ca2+. Typically, the Ca0.88Ba0.12MgSi2O6 ceramic can be well sintered at 1275 °C for 4 h with a maximum relative density of 99.3%, and possesses optimal microwave dielectric properties: εr=7.49, Q×f=64310 GHz, τf=-44.02 ppm/°C.