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Ab initio band structure calculations of the low-temperature phases of Ag2Se, Ag2Te and Ag3AuSe2 |
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| Authors: | C.M. Fang R.A. de Groot G.A. Wiegers |
| Affiliation: | a Electronic structure of Materials, Research Institute for Materials, Toernooiveld 1, 6525 ED Nijmegen, The Netherlands b Laboratory of Solid State and Material Chemistry, Technical University of Eindhoven, Post-bus 513, 5600 MB Eindhoven, The Netherlands c Inorganic Solid State Chemistry Laboratory, Materials Science Center, University of Groningen, Nijenborgh 4, 9747 AG, Groningen, The Netherlands |
| Abstract: | Ab initio band structure calculations were performed for the low-temperature modifications of the silver chalcogenides β-Ag2Se, β-Ag2Te and the ternary compound β-Ag3AuSe2 by the local spherical wave (LSW) method. Coordinates of the atoms of β-Ag2Se and β-Ag3AuSe2 were obtained from refinements using X-ray powder data. The structures are characterized by three, four and five coordinations of silver by the chalcogen, a linear coordination of gold by Se, and by metal-metal distances only slightly larger than in the metals. The band structure calculations show that β-Ag3AuSe2 is a semiconductor, while β-Ag2Se and β-Ag2Te are semimetals with an overlap of about 0.1-0.2 eV. The Ag 4d and Au 5d states are strongly hybridized with the chalcogen p states all over the valence bands. β-Ag2Se and β-Ag2Te have a very low DOS in the energy range from about −0.1 to +0.5 eV. The calculated effective mass β-Ag2Se is about 0.1-0.3 me for electrons and 0.75 me for holes, respectively. |
| Keywords: | A. Chalcogenides C. X-ray powder diffraction C. Ab initio calculations D. Crystal structure D. Electronic structure |
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