Effects of crystallization behaviour on microwave dielectric properties of (Ca1-xMg (x))SiO3 glass-ceramics

摘要

The microwave dielectric properties of (Ca1-xMg (x))SiO3 (0.2 <= x <= 0.6) glass-ceramics were investigated based on their crystallization behaviour as a function of heat-treatment temperatures from 800 degrees C to 1000 degrees C. With increasing Mg2+ content (x), the crystalline phases of the heat-treated specimens changed from wollastonite (CaSiO3) to diopside (CaMgSi2O6). For the same composition of heat-treated specimens, the degree of crystallization of wollastonite decreased and that of diopside increased with increasing heat-treatment temperature. The quality factors (Qf) of the heat-treated specimens were dependent on the amount of glass remaining after crystallization. However, the dielectric constants (K) and the temperature coefficients of resonant frequency (TCF) of the heat-treated specimens did not change significantly with the glass content. Good microwave dielectric properties with values of K=7.15, Qf=40,932 GHz, and TCF= -15.98 ppm/degrees C were obtained in (Ca1-xMg (x))SiO3 glass-ceramics with x=0.4 that was heat treated at 900 degrees C for 3 h. (C) 2017 Elsevier Ltd. All rights reserved.