Phase transition, microstructure and microwave dielectric properties of α-CaSiO_3 ceramics with SiO_2 addition

摘要

The effect of SiO_2 addition on phase transition, microstructure and microwave dielectric properties of α-CaSiO_3 ceramics was reported for the first time. The X-ray diffraction analysis confirmed that the phase transformation from cyclo-CaSiO_3 to pseudo-CaSiO_3 was inhibited with the increase of SiO_2 content. It was observed that the average grain size decreased with the increasing addition of SiO_2 by scanning electron microscope. The τ_f of the SiO_2-added α-CaSiO_3 ceramics almost remained constant with the SiO_2 content increased, while the ε_r and Q × f changed obviously. The optimized properties were determined for SiO_2 6 wt% additive α-CaSiO_3 ceramics sintered at 1,350 ℃: ε_r = 7.37, Q×f= 33,714 GHz and τ_f= -11.08 ppm/℃.