Microwave dielectric properties of cordierite-diopside glass-ceramics

The dependence of microwave dielectric properties on the crystallization behavior of (1-x) Mg2Al4Si5O18 – xCaMgSi2O6 glass-ceramics was investigated as a function of the CaMgSi2O6 content (x) and heat-treatment temperatures. The crystallization behaviors of the specimens were affected by the peak temperature of crystallization, the crystalline phases, and degree of crystallization. The amounts of crystalline phases of the specimens were quantitatively evaluated by X-ray diffraction analysis using a combination of the Rietveld and the reference intensity-ratio method. For the specimens with x = 0.1 heat-treated at 1160 °C for 3 h, a single phase of α-cordierite (Mg2Al4Si5O18) was detected and showed the maximum degree of crystallization. The overall dielectric constant (K) of the specimens was affected by the density and the K of diopside. The quality factor (Qf) of the specimens was dependent on the crystalline content of α-cordierite through the entire range of compositions. The measured dielectric constants of the specimens are also compared with those predicted by various dielectric mixing models.