Hydrogen-Substituted Superconductors SmFeAsO1鈥搙Hx Misidentified As Oxygen-Deficient SmFeAsO1鈥搙

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• 作者：Yoshinori Muraba ; Soshi Iimura ; Satoru Matsuishi ; Hideo Hosono
• 刊名：Inorganic Chemistry
• 出版年：2015
• 出版时间：December 7, 2015
• 年：2015
• 卷：54
• 期：23
• 页码：11567-11573
• 全文大小：460K
• ISSN：1520-510X

文摘

We investigated the preferred electron dopants at the oxygen sites of 1111-type SmFeAsO by changing the atmospheres around the precursor with the composition of Sm:Fe:As:O = 1:1:1:1 鈥?x in high-pressure synthesis. Under H₂O and H₂ atmospheres, hydrogens derived from H₂O or H₂ molecules were introduced into the oxygen sites as a hydride ion, and SmFeAsO_1鈥?i>xH_x was obtained. However, when the H₂O and H₂ sources were removed from the synthetic process, nearly stoichiometric SmFeAsO was obtained and the maximum amount of oxygen vacancies introduced remained x = 0.05(4). Density functional theory calculations indicated that substitution of hydrogen in the form of H^{鈥?/sup> is more stable than the formation of an oxygen vacancy at the oxygen site of SmFeAsO. These results strongly imply that oxygen-deficient SmFeAsO_1鈥?i>x reported previously is SmFeAsO_1鈥?i>xH_x with hydride ion incorporated unintentionally during high-pressure synthesis.}