Differences in local structures around zirconium atoms in Eu2Zr2O7 and La2Zr2O7

Extended X-ray absorption fine structure (EXAFS) analyses of the Eu2Zr2O7 and La2Zr2O7 pyrochlore composition oxides were performed to examine differences in the local structures around the Zr atoms. In the EXAFS analyses of Eu2Zr2O7, the amplitude reduction factor of Zr16c-O8a was considerably large, indicating that a part of the oxygen vacancy site (8a) was occupied by oxide ions. Furthermore, the occupancy of the 8a site determined by Rietveld refinement of the X-ray diffraction data for Eu2Zr2O7 was 0.32(2), which was consistent with the EXAFS results. From the EXAFS analyses of La2Zr2O7, oscillation in the high wavenumber k-range sharpened with decreasing temperature, and the mean square relative displacement (MSRD) values of the ZrO peak in the R-space were small compared to those of Eu2Zr2O7. Therefore, the disorder in the local structures around the Zr atoms of La2Zr2O7 was determined to be smaller than that of Eu2Zr2O7. [Display omitted] •Local crystal structure analysis by EXAFS of Eu2Zr2O7 and La2Zr2O7 between 100 and 500 K.•Oxygen vacancies in Eu2Zr2O7 are distributed in the 8a and 48f sites.•La2Zr2O7 has oxygen vacancies localized at the 8a site.•The Rietveld refinement results of XRD are supported by the results of EXAFS.