Structure and ferroelasticity of tetramethylammonium-hexafluoroosmate(IV), (TMA)(2)[OsF6]

R (3) over bar) and of the recently reported (TMA)(2)[PtF6] and (TMA)(2)[IrF6] (Fm (3) over barm --> I4/m) are described by Landau's theory. -->
Jazyk: English
ISSN: 0044-2968
Přístupová URL adresa: https://explore.openaire.eu/search/publication?articleId=narcis______::6c8507dd54ac9e8e867bb0da1a2b77c4
https://research.rug.nl/en/publications/d47cecca-88c4-4014-badd-9d21b39adbaa
Rights: RESTRICTED
Přírůstkové číslo: edsair.narcis........6c8507dd54ac9e8e867bb0da1a2b77c4
Autor: Kuppers, H, Gobel, O, Bruhn, C, Schmahl, WW
Přispěvatelé: University of Groningen
Jazyk: angličtina
Rok vydání: 2001
Zdroj: Zeitschrift fur Kristallographie, 216(6), 354-360
ISSN: 0044-2968
Popis: (TMA)(2)[OsF6] has at room temperature a rhombohedral structure (space group R (3) over bar) which is pseudocubic (K-2[PtCl6]-type). a = 8.0565(6) Angstrom, r = 20.020(3) Angstrom (hexagonal setting). Double refraction decreases linearly with increasing temperature and disappears above 434 K which indicates cubic symmetry of the high temperature phase. The change from the cubic high temperature structure to the rhombohedral structure is characterized by a ferrorotative tilt of the [OsF6] octahedra and the TMA tetrahedra. Evidence of ferroelasticity follows from the switching of the trigonal c-axis by the application of directional pressure. The phase transitions of (TMA)(2)[OsF6] (Fm (3) over barm --> R (3) over bar) and of the recently reported (TMA)(2)[PtF6] and (TMA)(2)[IrF6] (Fm (3) over barm --> I4/m) are described by Landau's theory.
Databáze: OpenAIRE
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