65 research outputs found
Crystal structure of the pyrochlore oxide superconductor KOsO
We report the single-crystal X-ray analysis of the structure of the
pyrochlore oxide superconductor KOsO. The structure was identified as
the -pyrochlore structure with space group and lattice
constant = 10.089(2)~\AA at 300 K: the K atom is located at the 8 site,
not at the 16 site as in conventional pyrochlore oxides. We found an
anomalously large atomic displacement parameter =
0.0735(8)~\AA at 300 K for the K cation, which suggests that the K cation
weakly bound to an oversized OsO cage exhibits intensive
rattling, as recently observed for clathrate compounds. The rattling of A
cations is a common feature in the series of -pyrochlore oxide
superconductors AOsO (A = Cs, Rb and K), and is greatest for the
smallest K cation.Comment: 5 pages, 5 figures, to appear in J. Solid. State. Che
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