| Thème(s) : |
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Physique/Physique/Chimie-Physique
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| Titre : |
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Crystal structures of Th(OH)PO_4, U(OH)PO_4 and Th_2 O(PO_4)_2. Condensation mechanism of M^IV (OH)PO_4 (M = Th, U) into M_2 O(PO_4)_2 |
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| Auteur : |
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N. Dacheux1, N. Clavier1, G. Wallez2, M. Quarton2 |
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| Laboratoire : |
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| Résumé : |
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Three new crystal structures, isotypic with β-Zr2O(PO4)2, have been resolved by the Rietveld method. All crystallize with an orthorhombic cell (S.G.: Cmca) with a = 7.1393(2) Å, b = 9.2641(2) Å, c = 12.5262(4) Å, V = 828.46(4) Å3 and Z = 8 for Th(OH)PO4; a = 7.0100(2) Å, b = 9.1200(2) Å, c = 12.3665(3) Å, V = 790.60(4) Å3 and Z = 8 for U(OH)PO4; a = 7.1691(3) Å, b = 9.2388(4) Å, c = 12.8204(7) Å, V = 849.15(7) Å3 and Z = 4 for Th2O(PO4)2. By heating, the M(OH)PO4 (M = Th, U) compounds condense topotactically into M2O(PO4)2, with a change of the environment of the tetravalent cation that lowers from 8 to 7 oxygen atoms. The lower stability of Th2O(PO4)2 compared to that of U2O(PO4)2 seems to result from this unusual environment for tetravalent thorium. |
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| Type de publication : |
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Communications avec actes |
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Date de publication
ou d'écriture : |
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2007 |
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Nom du périodique
Titre de l'ouvrage : |
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Solid State Sciences |
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| Audience : |
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internationale |
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| Volume : |
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9 |
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| Page/Article : |
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619-627 |
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| Editeur : |
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Elsevier |
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| Nom du colloque : |
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1st International Symposium on Structure-Property Relationships in Solid State Materials |
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| Ville du colloque : |
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Bordeaux |
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| Date du colloque (début) : |
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06/2006 |
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| Speaker : |
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N. Dacheux |
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