Phase Composition and Microwave Dielectric Properties of ZnAl2O4–Co2TiO4 Low-Permittivity Ceramics with High Quality Factor


  • D. Suvorov—contributing editor

  • This work was financially supported by the National Natural Science Foundation of China (NSFC-50902055), Program for New Century Excellent Talents in University (NCET-07-0329), and China Postdoctoral Science Foundation (CPSF-20080440925).

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Phase composition and microwave dielectric properties of (1−x)ZnAl2O4xCo2TiO4 ceramics synthesized by a conventional solid-state reaction were investigated. ZnAl2O4 can form a solid solution with Co2TiO4 for x≤0.3 and x≥0.7, while subgrains with ZnAl2O4-based and Co2TiO4-based spinel phase composition appear alternately on the same large grains for 0.4≤x≤0.6. The ɛr and τf value of the (1−x)ZnAl2O4xCo2TiO4 ceramics increase within the range of 8.3–16.9 and −71.3 to −40.8 ppm/°C with the increasing of x value, respectively. And the Q×f values with 147 600 GHz at x=0.2, 127 000 GHz at x=0.5, and 148 810 GHz at x=0.8 are all obviously higher than that of the end member ZnAl2O4 (96 800 GHz) and Co2TiO4 (98 060 GHz), which results from structural stability and lower inner stress.