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Temperature-stable microwave dielectric ceramics in the Ca5A2Ti1-xZrxO12 (A = Nb, Ta) system

Published online by Cambridge University Press:  01 October 2004

Pazhoor Varghese Bijumon  and
Mailadil Thomas Sebastian
Pazhoor Varghese Bijumon
Affiliation:
Ceramic Technology Division, Regional Research Laboratory, Trivandrum 695 019, India
Mailadil Thomas Sebastian*
Affiliation:
Ceramic Technology Division, Regional Research Laboratory, Trivandrum 695 019, India
*
a)Address all correspondence to this author. e-mail: mailadils@yahoo.com
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Abstract

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 Ca5Nb2Ti1−xZrxO12 system as x increases from 0 to 1, ϵr decreases from 48 to 25, Qu× f from 26,000 to 19,000 GHz, and τf from +40 to −21 ppm/°C. In Ca5Ta2Ti1−xZrxO12 ceramics, ϵr varies from 38 to 22, Quxf 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 Ca5Ta2Ti0.7Zr0.3O12 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).

Keywords

CeramicSinteringDielectric properties

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Articles
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Journal of Materials Research , Volume 19 , Issue 10 , October 2004 , pp. 2922 - 2928
Copyright
Copyright © Materials Research Society 2004

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