Les differentes formes cristallines de Y3ReO8: Relations avec la structure fluorine |
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| Authors: | G Baud J-P Besse R Chevalier M Gasperin |
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| Institution: | Equipe de Cristallographie et Physico-Chimie des Matériaux associée au CNRS (ERA 897), Université de Clermont H, B.P. 45, 63170 Aubiere, France;Laboratoire de Minéralogie-Cristallographie associé au CNRS (LA 09), Université P. et M. Curie, 4, Place Jussieu, 75230 Paris Cedex 05, France |
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| Abstract: | The monoclinic Y3ReO8β phase is synthetized at 40 kbar and 900°C. The crystal structure is solved to an R value of 0.058 for 1341 observed reflections, by conventional methods using automated four-circle diffractometer data. This structure can be visualized as a fluorite-related superstructure, the large difference between the ionic radii of Re7+ and Y3+ being favorable to cation ordering. The heating to 500°C of this phase under atmospheric pressure leads to a disordered fluorite structure of the form Y3ReO8α. An intermediary metastable phase Y3ReO8α′ is obtained by heating a Y3ReO8β single crystal to 350°C. The structural relations between these three crystalline forms of Y3ReO8 and the fluorite structure are discussed. |
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| Keywords: | Author to whom all correspondence should be addressed |
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