Studies of U(C5H5)3Cl: I-Evidence for structural phase transitions below room temperature

Autor:	Philippe E. Raison, P. J. Brown, A. Gonthier-Vassal, B. Kanellakopulos, J. M. Kiat, P. Schweiss, G. H. Lander, Christos Apostolidis, Jean Rebizant, A. Delapalme
Rok vydání:	1994
Předmět:	Inorganic Chemistry Diffraction Phase transition Crystallography Cyclopentadienyl complex Chemistry Neutron diffraction General Materials Science Neutron Crystallite Triclinic crystal system Condensed Matter Physics Single crystal
Zdroj:	Zeitschrift für Kristallographie - Crystalline Materials. 209:720-726
ISSN:	2196-7105 2194-4946
DOI:	10.1524/zkri.1994.209.9.720
Popis:	We have used neutron and X-ray diffraction techniques on both single crystal and polycrystalline samples to examine the symmetry of the unit cell of the organometallic compound uranium tris(cyclopentadienyl)chlorine, U(C5H5)3Cl, as a function of temperature below 300 K. Two phase transitions occur. The first, at 245 K, results in a change of space group but the monoclinic symmetry is retained; the second, at 78 K, results in the material becoming triclinic. Important differences are observed between the results obtained with neutron and X-ray diffraction; the latter fail to show clear evidence for the transition at 78 K. We believe this is a consequence of the different penetration depths of the two radiations. Calorimetric data confirms the presence of the 245 K transition.
Databáze:	OpenAIRE
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