Electronic structure and dielectric properties of ZrO2-CeO2 mixed oxides

Abstract

ZrO2-CeO2 mixed ceramics were studied for their local electronic structure and dielectric properties. X-ray diffraction (XRD), scanning electron microscope (SEM), X-ray absorption fine structure (XAFS) and frequency dependence dielectric constant measurements were performed on the samples. Rietveld refinements and quantitative phase analysis of ZrO2-CeO2 ceramics showed an increased concentration of tetragonal ZrO2 and cubic Zr0.5Ce0.5O2 phases at the expense of parent monoclinic ZrO2. The morphology of the ZrO2-CeO2 ceramics remained invariant for all of the fractional percentages of CeO2 loading. O K-edge and Ce M-5,M-4-edge NEXAFS showed the oxygen vacancies and Ce3+-Ce4+ redox pair formation in ZrO2-CeO2 ceramics, which is further corroborated by Ce L-3-edge XAFS. The higher CeO2 molar ratios containing ZrO2-CeO2 ceramics showed higher epsilon', epsilon '' and sigma(ac) and lower tan delta.