Correlation Between Structural Characteristics and Microwave Dielectric Properties of Scheelite Ca1−xCdxMoO4 Solid Solution

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Author to whom correspondence should be addressed. e-mail: vrkm@iitm.ac.in

Abstract

Ca1−xCdxMoO4 (x = 0.0, 0.2, 0.4, 0.6, 0.8, and 1.0) ceramics were prepared by solid-state reaction method. Tetragonal scheelite structure with I41/a space group was observed in all these compositions. Microwave dielectric properties such as quality factor (Q × f), dielectric constant (εr), and temperature coefficient of resonant frequency (τf) were measured in the microwave frequency range. Rietveld refinement was performed on all these compositions and bond valences of A-, B-site cation, and oxygen were calculated. Influence of these structural parameters on the microwave dielectric properties was examined. Q × f was correlated with the average covalence of A-, B-site cations. The variation in εr was explained with ionic polarizability of Cd+2 ions. The deviation of observed polarizability from theoretical polarizability and τf of all these compositions were explained with oxygen bond valence. The well-sintered Ca1−xCdxMoO4 ceramics showed highly promising microwave dielectric properties (εr = 8–10, Q × f = 46000–53000 GHz and τf = −22 to −57 ppm/°C).

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