Two metal chalcogenides, Hg2Te2X2 (XBr, I): 3-D framework constructed from novel left-handed helices |
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Authors: | Wen-Tong Chen Ming-Sheng Wang Gang Xu Jin-Shun Huang |
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Institution: | a State Key Laboratory of Structural Chemistry, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou, Fujian 350002, PR China b Graduate School of Chinese Academy of Sciences, Beijing 100039, PR China |
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Abstract: | Two isostructural metal chalcogenides, Hg2Te2Br2 (1) and Hg2Te2I2 (2), were obtained by solid-state reactions and structurally characterized. Compounds 1 and 2 crystallize in the acentric space group P43212 of the tetragonal system with eight formula units in a cell: a=10.2388(9), c=14.480(2) Å, V=1518.0(3) Å3, R1/wR2=0.0670/0.1328 for 1 and a=10.711(3), c=15.025(8) Å, V=1724(1) Å3, R1/wR2=0.0637/0.1233 for 2. Both compounds are characterized by a three-dimensional (3-D) framework structure, which is composed by interconnected left-handed helices formed by both tetrahedral and trigonal Hg atoms. Optical absorption spectra of 1 and 2 reveal the presence of sharp optical gaps of 2.06 and 1.85 eV, respectively, suggesting that both materials are semiconductors. TG-DTA measurements show that both compounds are thermally stable up to 200 °C. The composition of both compounds is well confirmed by the semiquantitative microscope analyses. |
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Keywords: | Chalcogenide Crystal structure Halide Mercury Solid-state reaction Tellurium |
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