Effect of CeO2 on Microwave Dielectric Properties of MgO–Al2O3–SiO2–TiO2 Glass-Ceramic

概要

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Glass-ceramics with a molar composition of 1.0MgO$\cdot$1.2Al2O3$\cdot$2.8SiO2$\cdot$1.2TiO2$\cdot$$x$CeO2, $x=0.2$, 0.4, 0.6, and 0.8, were prepared by one-step crystallization heat treatment of the parent glasses at 1150 °C for 2 h. The effects of CeO2 on crystalline phases, microstructure and microwave dielectric properties of the materials were investigated. The investigation shows that the glass-ceramics consist of three main crystalline phases. With the increase in CeO2, the perrierite phase (Ce2Ti2Si2O11) increases, while the rutile (TiO2) and $\alpha$-cordierite (Mg2Al4Si5O18) phases decrease. At the same time, the quality factor ($Q\times f$, $Q=1/\tan\delta$, $ f$ = resonant frequency) of the material increases slightly from 12,500 to 15,300 GHz, but the temperature coefficient of resonant frequency ($\tau_{f}$) of the material decreases markedly from $+116$ to $-5$ ppm/°C because of the decrease in the rutile phase. The dielectric constant ($\varepsilon_{\text{r}}$) of the material is in the range of 10.4–12.6, and it increases first when CeO2 increases and then decreases, with the maximum value appearing at $x=0.6$. Glass-ceramic with excellent microwave dielectric properties of $\varepsilon_{\text{r}}=10.4$, $Q\times f=15{,}300$ GHz, $\tau_{f}=-5$ ppm/°C, was obtained in this study.
2007-08-15