Effects of ion polarizability and oxygen vacancy on microwave dielectric properties of fluorite‐structured Ce_1−xCa_xO_2−x

Abstract

X‐ray diffractometer with Rietveld refinement and Raman spectroscopy were used for phase analysis. Ca doping results in decreased εr (24.09–21.52), Q × f (68 914–40 110 GHz), and τf (−50.0 ppm/°C to −60.2 ppm/°C) all decrease, which obviously does not conform to the mutual constraint relationship among the three parameters of microwave dielectric properties. The εr of Ce1−xCaxO2−x ceramics is affected by the ion polarizability and the Ce rattling and valence states, among which the rattling of Ce cations plays a dominant role. The presence of oxygen vacancies in Ce1−xCaxO2−x ceramics explains the decrease in Q × f. The τε, εr, and αL are responsible for the decrease in τf, especially for the ταm‐3αL values.