2014 Volume 122 Issue 1422 Pages 125-128
The effects of Li2CO3 additions on the densification and microwave dielectric properties of CaSiO3–1 wt % Al2O3 ceramics were investigated. With Li2CO3 addition, the densification temperature of CaSiO3–1 wt % Al2O3 ceramics could be effectively reduced from 1250 to 925°C. During the sintering process, Li2CO3 existed as a liquid phase and assisted the densification of CaSiO3–1 wt %Al2O3 ceramics, and then reacted with CaSiO3 to form Li2Ca3Si6O16 and Li2Ca4Si4O13 second phases. However, the Li2CO3 addition deteriorated the microwave dielectric properties because of the lower quality values of Li2Ca3Si6O16 and Li2Ca4Si4O13 phases. The proper Li2CO3 addition was found to be 2 wt %. Under this addition, microwave dielectric properties of εr = 7.33, Q×f = 21,904 GHz and τf = −34 ppm/°C were obtained for the CaSiO3–1 wt % Al2O3 ceramic sintered at 975°C for 2 h.