Abstract
The microwave dielectric properties of β-CaSiO3 glass−ceramics are compared with those of α-CaSiO3 ceramics. β-CaSiO3 is prepared using glass−ceramics method with two-step heat treatment at 730 °C for 1−7 h and at 900 °C for 3 h, and α-CaSiO3 is prepared using conventional solid-state reaction and sintered at 1460−1500 °C for 3 h. With increasing holding time at 730 °C, the degree of crystallisation and Qf of the β-CaSiO3 glass−ceramics increased. The β-CaSiO3 specimens heat-treated at 730 °C for 3 h and 900 °C for 3 h exhibit the following dielectric properties: K = 6.57, TCF = −36.22 ppm/°C, and Qf = 52,400 GHz (highest) for the entire range of heat treatment conditions. The Qf difference between β-CaSiO3 and α-CaSiO3 could be explained by the bond characteristics using Rietveld refinement. FT-IR analysis shows that the Ca−O bond is the dominant factor for the Qf of CaSiO3 ceramics compared to the Si−O bond. The higher Qf of β-CaSiO3 than that of α-CaSiO3 can be attributed to the higher bond strength of Ca−O for β-CaSiO3 than that for α-CaSiO3.