The Flexible Ba7UM2S12.5O0.5 (M = V, Fe) Compounds: Syntheses, Structures and Spectroscopic, Resistivity, and Electronic Properties

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• 作者：Adel Mesbah ; Wojciech Stojko ; Christos D. Malliakas ; S茅bastien Leb猫gue ; Nicolas Clavier ; James A. Ibers
• 刊名：Inorganic Chemistry
• 出版年：2013
• 出版时间：October 21, 2013
• 年：2013
• 卷：52
• 期：20
• 页码：12057-12063
• 全文大小：435K
• 年卷期：v.52,no.20(October 21, 2013)
• ISSN：1520-510X

文摘

Two new compounds, Ba₇UV₂S_12.5O_0.5 and Ba₇UFe₂S_12.5O_0.5, have been synthesized in fused-silica tubes by the direct combinations of V or Fe with U, BaS, and S at 1223 K. The compound Ba₇UV₂S_12.5O_0.5 crystallizes at 100 K in the Cs₇Cd₃Br₁₇ structure type in space group D_4h¹⁸鈥?i>I4/mcm of the tetragonal system. The compound Ba₇UFe₂S_12.5O_0.5 crystallizes at 100 K in space group D_4h⁵鈥?i>P4/mbm of the tetragonal system. The structures are very similar with V/S or Fe/S networks in which Ba atoms reside as well as channels large enough to accommodate additional Ba atoms and infinite linear US₅O chains. Each U atom is octahedrally coordinated to four equatorial S atoms, one axial S atom, and one axial O atom. The Fe/S network contains a S鈥揝 single bond, whereas the V/S network does not. The result is that the Fe³⁺ compound charge balances with 7 Ba²⁺, U⁴⁺, 2 Fe³⁺, 10.5 S^{2鈥?/sup>, S₂2鈥?/sup>, and 0.5 O2鈥?/sup>, whereas the V4+ compound charge balances with 7 Ba2+, U4+, 2 V4+, 12.5 S2鈥?/sup>, and 0.5 O2鈥?/sup>. Other differences between these two compounds have been characterized by Raman spectroscopy and resistivity measurements. DFT calculations have provided insight into the nature of their bonding. The overall structural motif of Ba₇UV₂S_12.5O_0.5 and Ba₇UFe₂S_12.5O_0.5 offers a remarkable flexibility in terms of the oxidation state of the incorporated transition metal.}