Effects of oxygen vacancy on bond ionicity and microwave dielectric properties of Y_xCe_1−xO_2−0.5x (x = 0–0.7) ceramics

Abstract

Novel YxCe1−xO2−0.5x (x = 0–0.7) ceramics, designed by replacing Ce4+ with Y3+, were prepared using a conventional oxide reaction. The oxygen vacancies, measured by X‐ray photoelectron spectroscopy and analyzed through the electronic structure calculated via the first‐principles method, were employed to investigate the effective valence electron charge, which plays a decisive role in calculating bond ionicity using P–V–L theory. After the substitution of Y3+ ions, the effective valence electron charge of the Ce–O bond changed because of an increase in oxygen vacancies, ultimately leading to a decrease in the Ce/Y–O bond ionicity of the YxCe1−xO2−0.5x ceramics. For microwave dielectric properties, when the YxCe1−xO2−0.5x (x = 0−0.5) ceramics were in the pure phase, porosity‐corrected permittivity and Q × f values depended on the bond ionicity, and the temperature coefficient of the resonance frequency was analyzed using the bond valence. When the YxCe1−xO2−0.5x (x = 0.6 and 0.7) ceramics were in multiple phases, the microwave dielectric properties were associated with the phase composition.