Densification, microstructure evolution, and microwave dielectric properties of Mg1-xCaxZrTa2O8 ceramics. Issue 8 (July 2017)

• Record Type: Journal Article
• Authors: Lin, Yung-Jen; Wang, Sea-Fue; Lai, Bo-Cheng; Liu, Yi-Xin; Chang, Ya-Ling; Yang, Jer-Ren
• Is Part Of: Journal of the European Ceramic Society. Volume 37:Issue 8(2017)
• Page Start: 2825
• Page End: 2831
• Publication Date: 2017-07
• Subjects: Microwave dielectric properties -- Wolframite -- Microstructure -- Densification; Ceramic materials -- Periodicals; Composite materials -- Periodicals; Matériaux céramiques -- Périodiques; Composites -- Périodiques; Ceramic materials; Composite materials; Periodicals; Electronic journals; 666.05
• DOI: 10.1016/j.jeurceramsoc.2017.02.058
• Languages: English
• ISSNs: 0955-2219

Abstract

Abstract: In this study, the effects of the Mg 2+ ions replaced by Ca 2+ ions on the microwave dielectric properties of newly developed MgZrTa2 O8 were investigated. Mg1-x Cax ZrTa2 O8 (x = 0–1.0) ceramics were prepared via a solid-state reaction method. Calcination of the mixed powders was performed at 1200 °C and sintering of the powder compacts was accomplished at temperatures from 1200 to 1550 °C. The substitution of Ca 2+ significantly inhibited the densification of Mg1-x Cax ZrTa2 O8, led to the expansion of the unit cells, and triggered the formation of a second phase, CaTa2 O6 . The porosity-corrected relative permittivity increased almost linearly with the x value because of the replacement of the less polarizable Mg 2+ ions by the more polarizable Ca 2+ ions. The variation in the Q × f values followed a similar trend as that of the sintered density, and the change trend in the τf values was in accordance with that of relative permittivity. The best composition appeared to be Mg0.9 Ca0.1 ZrTa2 O8, which showed excellent microwave dielectric properties of εr = 22.5, Q × f = 231, 951 GHz, and τf = −32.9 ppm/°C. The Q × f value obtained is the highest among the wolframite dielectric ceramics reported in literature.