Papers
Dielectric properties and crystal structure of Mg4Ta2O9 ceramics with Mg2+ substituted by Co2+
キーワード:
Dielectric,
Microwave ceramics
2014 年 122 巻 1427 号 p. 556-560
詳細
2014 年 122 巻 1427 号 p. 556-560
Dielectric properties of (Mg(1−x)Cox)4Ta2O9 (x = 0.01 to 0.09) prepared by solid state reaction were investigated. The maximum properties of the (Mg(1−x)Cox)4Ta2O9 (x = 0.05) system were namely, an obtained εr value of 12.27, a Q×f value of 440,000 GHz, and a τf value of −59 ppm/°C sintered at 1325°C. The theoretical polarizability of (Mg(1−x)Cox)4Ta2O9 increased with Co substitution, x. (Mg(1−x)Cox)4Ta2O9 with Mg2+ substituted by and Co2+ not only improved the microwave dielectric properties, but also decreased sintering temperature. From the calculation of the covalency of cation–oxygen bonds, it is found that the covalency of the Co–O bond is lower than that of the Mg–O bond and the difference in the covalency between these cation–oxygen bonds influences the temperature dependence of dielectric constant on the compounds. From our experiment, the best microwave dielectric property happens in (Mg0.95Co0.05)4Ta2O9 sintered at 1325°C for 4 h, and it’s Q×f is 440,000 GHz with τf = 59.5 ppm/°C.
