Hydration, Structure, and Superconductivity of KOs2O6·nH2O

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• 作者：Rosa Galati ; Charles Simon ; Christopher S. Knee ; Paul F. Henry ; Brian D. Rainford ; Mark T. Weller
• 刊名：Chemistry of Materials
• 出版年：2008
• 出版时间：February 26, 2008
• 年：2008
• 卷：20
• 期：4
• 页码：1652 - 1659
• 全文大小：376K
• 年卷期：v.20,no.4(February 26, 2008)
• ISSN：1520-5002

文摘

In moist air or by contact with water during washing, KOs₂O₆ absorbs water molecules into the structure to produce KOs₂O₆·nH₂O, 0 < n < 0.1. This water is reversibly lost on heating above ~430 K in flowing or static gas environments. Variable temperature powder neutron and X-ray diffraction show that an increase in lattice parameter occurs when water enters the pyrochlore structure and the water molecules are located in the α cages displacing a portion of the potassium ions to adjacent sites. On removing water the lattice parameter and structure revert to those of the normal β-pyrochlore crystallographic description. Hydration has the effect of reducing the onset of superconducting behavior from a critical temperature of 10.25 K in fully dry KOs₂O₆ to 9.75 K in KOs₂O₆·0.1H₂O.