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Crystal-structures of bismuth tellurohalides bitex (x=cl, br, i) from x-ray-powder diffraction dataстатья
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Дата последнего поиска статьи во внешних источниках: 18 июля 2013 г.
- Авторы: Shevelkov Av, Dikarev Ev, Shpanchenko Rv, Popovkin Ba
- Журнал: Journal of Solid State Chemistry
- Том: 114
- Номер: 2
- Год издания: 1995
- Издательство: Elsevier B.V.
- Местоположение издательства: Netherlands
- Первая страница: 379
- Последняя страница: 384
- DOI: 10.1006/jssc.1995.1058
- Аннотация: Crystal structures of the bismuth tellurohalides BiTeCl (prepared for the first time), BiTeBr, and BiTeI were refined based on X-ray powder diffraction data using a full-profile Rietveld method. All three phases crystallize in a hexagonal system: BiTeCl; space group P6(3)mc (No. 186), a = 4.2426(1) Angstrom, c = 12.397(1) Angstrom, z = 2, R(I) = 0.065, R(Pr) = 0.104; BiTeBr, space group P (3) over bar m1 (No. 164), a = 4.2662(1) Angstrom, c = 6.487(1) Angstrom, z = 1, R(I) = 0.042, R(Pr) 0.082; BiTeI, space group P3m1 (No. 156), a = 4.3392(1) Angstrom, c = 6.854(1) Angstrom, z = 1, R(I) = 0.054, R(Pr) = 0.129. Bismuth tellurohalides do not belong to the SbSBr structure type. BiTeBr has a 2H-CdI2-type structure with tellurium and bromine atoms statistically distributed within a two-layered packing. BiTeI exhibits a distorted variant of the former structure with an ordering of tellurium and iodine atoms in an anionic subcell. In BiTeCl, layers of tellurium and chlorine atoms alternate along the c direction of the unit cell, forming a four-layered (hc)(2) packing. Bismuth atoms occupy all octahedral interstices in each second layer. The common feature that the three structures share is the corrugated (BiTe)(+) layers which resemble the geometry of bismuth layers in metallic bismuth. The structures are described in terms of a semi-ionic model, according to which bismuth and tellurium atoms form positively charged (BiTe)(+) layers, while bismuth-halogen contacts are considered to be ionic. (C) 1995 Academic Press, Inc.
- Добавил в систему: Шевельков Андрей Владимирович