| Abstrakt: |
Ca5A2Ti1-xZrxO12 (A = Nb, Ta) ceramics were prepared through conventional solid-state ceramic route for 0 ≤ x ≤ 1. The crystal structures of the ceramics were studied by x-ray diffraction techniques, and dielectric properties were measured at microwave frequencies. In the Ca5Nb2Til-xZrxO12 system as x increases from 0 to 1, &espsilon;r decreases from 48 to 25, Qu x f from 26,000 to 19,000 GHz, and τf from +40 to -21 ppm/°C. In Ca5Ta2Til-xZrxO12 ceramics, &epsilonr varies from 38 to 22, Qouxf from 33,000 to 24,000 GHz, and τf from +10 to -26 ppm/°C as x is changed from 0 to 1. The variation of microwave dielectric properties with bond valence and electronegativity in the two systems were also investigated. Ca5Nb2Ti0.2Zr0.8O12 and Ca5Ta2Ti2Ti0.7Zr0.3O12 dielectric ceramics were found to have stable resonant frequency with temperature and are potential candidates for applications in personal and satellite communication systems in the S and C band (2-8 GHz). [ABSTRACT FROM AUTHOR] |
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