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Microwave dielectric properties of $(1-x)CaWO_4-xYNbO_4$ ceramics  

Kim, Su-Jung (Department of Materials Engineering, Kyonggi University)
Kim, Eung-Soo (Department of Materials Engineering, Kyonggi University)
Publication Information
Journal of the Korean Crystal Growth and Crystal Technology / v.17, no.5, 2007 , pp. 217-222 More about this Journal
Abstract
Microwave dielectric properties of $(1-x)CaWO_4-xYNbO_4$ ceramics have been investigated as a function of $YNbO_4$ content($0.05{\leq}x{\leq}0.4$). A single phase with tetragonal scheelite structure was obtained up to x=0.10 and then the secondary phase with fergusonite structure was increased. With the increase of $YNbO_4$ content, apparent densities of the specimens were decreased. This results were due to the lower theoretical density of $YNbO_4(5.581g/cm^3)$ than that of $CaWO_4(6.117g/cm^3)$. Dielectric constant(K) and quality factor(Qf) were decreased with $YNbO_4$ content which could be attribute to the decrease of density and the increase of secondary phase. Temperature coefficient of resonant frequency (TCF) of the specimens with the $YNbO_4$ content was depended on dielectric mixing rule.
Keywords
$CaWO_4-YNbO_4$; Microwave dielectric properties; Microstructure; Dielectric mixing rule;
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