Liquid Phase Sintering and Microwave Dielectric Properties of Ba(Mg1/3Ta2/3)O3 Ceramics

概要

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The effect of CuO addition on the microstructures and the microwave dielectric properties of barium magnesium tantalate Ba(Mg1/3Ta2/3)O3 ceramics has been investigated. It is found that low level-doping of CuO (up to 1 wt%) can significantly improve the density of the specimens and their microwave dielectric properties. The density of doped Ba(Mg1/3Ta2/3)O3 ceramics can be increased beyond 96% of its theoretical density by at sintering 1440°C due to the liquid phase effect of CuO addition observed by scanning electron microscopy. The second phase was not observed for ceramics with 0.25 to1 wt% CuO additions. The dielectric constant ($\varepsilon_{\text{r}}$) and temperature coefficient of resonant frequency ($\tau_{\text{f}}$) were not significantly affected, while the nonloaded quality factors $Q$ were effectively promoted by CuO addition. The $\varepsilon_{\text{r}}$ value of 24.2, $Q\times f$ value of 173000 (at 10 GHz) and $\tau_{\text{f}}$ value of 1.5 ppm/°C were obtained for Ba(Mg1/3Ta2/3)O3 ceramics with 0.5 wt% CuO addition sintered at 1470°C for 4 h.
2002-02-15