High-Permittivity Temperature-Stable Ceramic Dielectrics with Low Microwave Loss

TLDR: In this article, the properties of temperature-stable compositions in the systems Ca(Zr,Ti)O3 and (Ba,Sr),Zr O3 and CaZrO3 were investigated.

Abstract: The compounds SrZrO3 and CaZrO3 combine high permittivity with low loss and positive temperature coefficient of permittivity. Temperature-stable materials were produced by forming solid solutions between these zirconates and zirconates or titanates having negative coefficients. The properties of temperature-stable compositions in the systems Ca(Zr,Ti)O3 and (Ba,Sr)(Zr,Ti)O3 were investigated. At 4 GHz the relative permittivities were from 29 to 35 and the loss tangents from 3 to 11×10−4. Both permittivity and microwave loss increased as the principal alkaline-earth ion was changed from Ca to Sr to Ba, but the higher losses could be reduced by adding ∼1 mol% Nb or Ta. Dense fine-grained ceramics with the properties required for microwave applications were prepared.