Substitution Effects in Zintl Phases: Synthesis and Crystal Structure of the Novel Phases Ae3Sn4−xBi1+x (x ≤ 1; Ae = Sr,Ba) Containing Shubnikov‐Type Nets $^{2}_{\infty}\rm [Sn_{4-x}Bi_{x}]$ |
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Authors: | Siméon Ponou Sung‐Jin Kim Thomas F Fässler Prof Dr |
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Institution: | 1. München, Department Chemie, Technische Universit?t München;2. München, Department Chemie, Technische Universit?t MünchenDepartment Chemie, Technische Universit?t München, Lichtenbergstr. 4, D‐85747 Garching/Germany |
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Abstract: | The compounds Ae3Sn4?xBi1+x (Ae = Sr, Ba) with x < 1 have been synthesized by solid‐state reactions in welded Nb tubes at high temperature. Their structures were determined by single crystal X‐ray diffraction studies to be tetragonal; space group I4/mcm (No. 140); Z = 4, with a = 8.968(1) Å, c = 12.859(1) Å for Sr3Sn3.36Bi1.64(3) ( 1 ) and a = 9.248(2), c = 13.323(3) Å for Ba3Sn3.16Bi1.84(3) ( 2 ). The structure consists of two interpenetrating networks formed by a 3D Ae6/2Bi substructure (anti‐ReO3 type) forming the host, and layers of interconnected four‐member units Sn4?xBix] with “butterfly”‐like shape as the guest. According to the Zintl‐Klemm concept, the compounds are slightly electron deficient and will be charge balanced for x = 1. The electronic structures of Ae3Sn4?xBi1+x calculated by the TB‐LMTO‐ASA method indicate that the compounds correspond to ideal semiconducting Zintl phases with a narrow band gap for x = 1 (zero‐gap semiconductor). The origin of the slight deviation from the optimal electron count for a valance compound is discussed. |
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Keywords: | Bismuth Crystal Structure Electronic Structure Intermetallic Compound Tin Zero‐gap Semiconductor |
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