Densification, microstructure evolution, and microwave dielectric properties of Mg1-xCaxZrTa2O8 ceramics

作者：Lin Yung Jen; Wang Sea Fue; Lai Bo Cheng; Liu Yi Xin; Chang Ya Ling; Yang Jer Ren

来源：Journal of the European Ceramic Society, 2017, 37(8): 2825-2831.

DOI：10.1016/j.jeurceramsoc.2017.02.058

• Microwave dielectric properties
• Wolframite
• Microstructure
• Densification

In this study, the effects of the Mg2+ ions replaced by Ca2+ ions on the microwave dielectric properties of newly developed MgZrTa2O8 were investigated. Mg1-xCaZrTa2O8 (x= 0-1.0) ceramics were prepared via a solid-state reaction method. Calcination of the mixed powders was performed at 1200 degrees C and sintering of the powder compacts was accomplished at temperatures from 1200 to 1550 degrees C The substitution of Ca2+ significantly inhibited the densification of Mg1-xCaxZrTa2O8, led to the expansion of the unit cells, and triggered the formation of a second phase, CaTa2O6. The porosity-corrected relative permittivity increased almost linearly with the x value because of the replacement of the less polarizable Mg2+ ions by the more polarizable Ca2+ ions. The variation in the Q x f values followed a similar trend as that of the sintered density, and the change trend in the,T-f values was in accordance with that of relative permittivity. The best composition appeared to be Mg0.6Ca0.1ZrTa2O8, which showed excellent microwave dielectric properties of epsilon(r) =22.5, Q x f = 231,951 GHz, and T-f = -32.9 ppm/degrees C. The Q x f value obtained is the highest among the wolframite dielectric ceramics reported in literature.

• 出版日期2017-7