Mixed-Valent NaCu4Se3: A Two-Dimensional Metal

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• 作者：Mihai Sturza ; Daniel E. Bugaris ; Christos D. Malliakas ; Fei Han ; Duck Young Chung ; Mercouri G. Kanatzidis
• 刊名：Inorganic Chemistry
• 出版年：2016
• 出版时间：May 16, 2016
• 年：2016
• 卷：55
• 期：10
• 页码：4884-4890
• 全文大小：483K
• 年卷期：0
• ISSN：1520-510X

文摘

The new ternary copper selenide NaCu₄Se₃ crystallizes in the RbCd₄As₃ structure type with the trigonal space group R3̅m and lattice constants a = 4.0316(4) Å and c = 31.438(8) Å. Its structure is built from two-dimensional slabs of ²/_∞[Cu₄Se₃] separated by Na⁺ cations. The compound is formally mixed-valent with Se^2–/Se^– atoms and exhibits metallic properties. It is a hole conductor with an electrical conductivity of ∼300 S cm^–1 at room temperature and a thermopower of ∼10 μV K^–1. Hall effect measurements indicate holes as the dominant carrier with a concentration of ∼6.12(1) × 10²¹ cm^–3 at 300 K. Density functional theory electronic structure calculations indicate p-type metallic behavior for the ²/_∞[Cu₄Se₃] framework, which is in a good agreement with the experimental metallic conductivity and Pauli paramagnetism.