Synthesis, Crystal Structure, Theoretical, and Resistivity Study of BaUSe3

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• 作者：Jai Prakash ; Maria S. Tarasenko ; Adel Mesbah ; Sébastien Lebègue ; Christos D. Malliakas ; James A. Ibers
• 刊名：Inorganic Chemistry
• 出版年：2016
• 出版时间：August 1, 2016
• 年：2016
• 卷：55
• 期：15
• 页码：7734-7738
• 全文大小：353K
• 年卷期：0
• ISSN：1520-510X

文摘

The black-colored compound BaUSe₃ has been synthesized at 1173 K by a stoichiometric reaction of the elements in a CsCl flux. BaUSe₃ crystallizes in the GdFeO₃ structure type. There is no change in structure between 100 and 298 K. The U atoms in this structure are octahedrally connected to six Se atoms. Each octahedral unit shares all six corners with neighboring octahedra, forming a three-dimensional network. BaUSe₃ can be charge balanced as Ba²⁺U⁴⁺(Se^2–)₃. DFT electronic structure calculations found BaUSe₃ to be antiferromagnetic in its ground state and to be a semiconductor with a band gap of 2.5 eV. The band gap is inconsistent with the black color of the material and with the small activation energy of 0.12(1) eV obtained from resistivity measurements. A UV–vis spectrum indicated that there was no band gap above 1 eV. It is possible that, for BaUSe₃, intrinsic and extrinsic impurities from the flux create midgap states that lead to the experimentally measured narrow optical gap. More likely, BaUSe₃ presents a challenge to DFT calculations as applied to 5f materials.