Effect of TiO_2 and CaTiO_3 additives on the sintering behavior and microwave dielectric properties of Ca(Mg_(0.92)Al_(0.08)) (Si_(0.96)Al_(0.04))_2O_6 ceramics

摘要

Ca(Mg_(0.92)Al_(0.08))(Si_(0.96)Al_(0.04))_2O_6 ceramics with different amounts of TiO_2/CaTiO_3 additions were prepared by the solid-state reaction method. The sintering behavior, microstructure and microwave dielectric properties of TiO_2/CaTiO_3-added ceramics were investigated. The control of the temperature coefficient of resonant frequency (τ_f) could be achieved by varying the content of TiO_2 or CaTiO_3. Particularly, TiO_2 reacted with the main ceramic phase of Ca(Mg,Al)(Si,Al)_2O_6 and produced secondary phases of MgTi_2O_5 and CaTiSiO_4O, which lowered the Q ×f values of the ceramics. TiO_2-added ceramics sintered at 1225 °C with 22 wt% TiO_2 additions showed dielectric properties of er= 12.06, Q ×f=5940 GHz and τ_f=2.24 ppm/°C. Comparing with the TiO_2-added ceramics, CaTiO_3 just existed as a separate component, and the Ca(Mg(0.92)Al_(0.08)) (Si_(0.96)Al_(0.04))_2O_6 ceramic sintered at 1250 °C with 10wt% CaTiO_3 additions showed a good combination of dielectric properties: ε_r=9.6, Q ×f= 32,590 GHz and τ_f= - 1.53 ppm/°C.