PAUWELS, Damien; DEMOURGUES, Alain; LARONZE, Hervé; GRAVEREAU, Pierre; GUILLEN, François; ISNARD, Olivier; TRESSAUD, Alain

doi:10.1016/S1293-2558(02)00038-9

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PAUWELS, Damien
Institut de Chimie de la Matière Condensée de Bordeaux [ICMCB]

DEMOURGUES, Alain
Institut de Chimie de la Matière Condensée de Bordeaux [ICMCB]

LARONZE, Hervé
Institut de Chimie de la Matière Condensée de Bordeaux [ICMCB]

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Solid State Sciences. 2002, vol. 4, n° 11-12, p. 1471-1479

Elsevier

Résumé en anglais

In the structure of α-LnSF and Ln2AF4S2 (A=Ca, Sr) compounds which can be considered as formed of layer stacking, the rare earth and fluorine atoms form [Ln2F2]4+ or [Ln2AF4]4+ fluorite-type blocks which alternate with double [S2]4− layers along the c-axis. Then, it appears possible to modify the size of the fluorite-type block without any modification of its charge. In the case of rare earth oxyfluorosulfides, two new classes of compounds Ln3OF3S2 (Ln=La, Ce) and La2O1.5FS were identified. The structures of these compounds are related to α-LnSF and Ln2O2S networks. In these frameworks, the charge of the blocks containing the rare earth ions can be 2+ or 4+. These blocks alternate with single or double layers of sulfur atoms. The local geometry (number of neighbors, bond distances and angles) around the rare earth varies as a function of the number of the sulfur sheets. Absorption properties in UV-visible range are correlated with the structural features.< Réduire

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Electronic transitions

UV-visible absorption

Structure refinement

Rare earth

Fluorosulfides

Oxyfluorosulfides

Powder X-ray/neutron diffraction

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Structural features of new rare earth-based mixed anions (O, S, F) compounds: relationships between optical absorption and rare earth environment

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