Calcining Temperature Dependence of Microwave Dielectric Properties of ($1-x$)ZnAl2O4–$x$TiO2 ($x=0.21$) Ceramics

概要

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($1-x$)ZnAl2O4–$x$TiO2 ($x = 0.21$) ceramics were synthesized at 1500 °C using the solid-state reaction after the starting powders were calcined at 1050–1250 °C. The effects of calcining temperature on the microstructures, phase compositions, and microwave dielectric properties of the ceramics had been investigated. In the calcined ($1-x$)ZnAl2O4–$x$TiO2 ($x = 0.21$) powders, the amount of the secondary phase Zn2Ti3O8 decreases gradually with increasing calcining temperature and it disappears at more than 1150 °C. The $\varepsilon_{\text{r}}$ and $Q\cdot f$ values increase slowly with increasing calcining temperature and then decrease after reaching the maximum value at 1150 °C, whereas the $\tau_{\text{f}}$ values are nearly independent of the calcining temperature and approach zero. When the calcining temperature reaches 1150 °C, the optimal microwave dielectric properties of the ($1-x$)ZnAl2O4–$x$TiO2 ($x = 0.21$) ceramics can be exhibited with a $\varepsilon_{\text{r}}$ of 11.6, a $Q\cdot f$ of 74,000 GHz (at about 6.5 GHz), and a $\tau_{\text{f}}$ of $-0.4$ ppm/°C.
2007-08-25