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ABSTRACT: The crystal structure of the β-pyrochlore oxide superconductor KOs2O6 is re-examined. A single-crystal X-ray diffraction (XRD) analysis at room temperature first revealed that the compound crystallizes in a cubic structure with the centrosymmetric space group , as in conventional pyrochlore oxides. Later, however, Schuck et al. claimed a different non-centrosymmetric structure based on their single-crystal XRD analysis. To unambiguously determine the true crystal structure of KOs2O6, we carried out high-resolution synchrotron powder X-ray and convergent-beam electron diffraction measurements at room temperature. The space group was determined with high reliability to be centrosymmetric , not . This confirms the importance of the K atom location in a high-symmetry site, which causes unusually large rattling of the K atom.
Solid State Communications 01/2009; · 1.53 Impact Factor