Structure solution of the complex γ-La6W2O15

Autor: Kodjikian, Stéphanie, Lepoittevin, Christophe, Klein, Holger, Schönenberger, Thomas, Lebedev, Oleg, Leynaud, Olivier, Chambrier, Marie-Hélène, Goutenoire, François
Přispěvatelé: Optique et microscopies (POM), Institut Néel (NEEL), Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019]), Matériaux, Rayonnements, Structure (MRS), Laboratoire de cristallographie et sciences des matériaux (CRISMAT), École Nationale Supérieure d'Ingénieurs de Caen (ENSICAEN), Normandie Université (NU)-Normandie Université (NU)-Centre National de la Recherche Scientifique (CNRS)-Université de Caen Normandie (UNICAEN), Normandie Université (NU)-Institut de Chimie du CNRS (INC), X'Press (X'Press), UCCS Équipe Couches Minces & Nanomatériaux, Unité de Catalyse et Chimie du Solide - UMR 8181 (UCCS), Centrale Lille Institut (CLIL)-Université d'Artois (UA)-Centrale Lille-Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC)-Université de Lille-Centrale Lille Institut (CLIL)-Université d'Artois (UA)-Centrale Lille-Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC)-Université de Lille, Institut des Molécules et Matériaux du Mans (IMMM), Le Mans Université (UM)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS), Optique & Microscopies (NEEL - POM), Matériaux, Rayonnements, Structure (NEEL - MRS), Université de Caen Normandie (UNICAEN), Normandie Université (NU)-Normandie Université (NU)-École Nationale Supérieure d'Ingénieurs de Caen (ENSICAEN), Normandie Université (NU)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche sur les Matériaux Avancés (IRMA), Normandie Université (NU)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Rouen Normandie (UNIROUEN), Normandie Université (NU)-Institut national des sciences appliquées Rouen Normandie (INSA Rouen Normandie), Institut National des Sciences Appliquées (INSA)-Normandie Université (NU)-Institut National des Sciences Appliquées (INSA)-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Rouen Normandie (UNIROUEN), Institut National des Sciences Appliquées (INSA)-Normandie Université (NU)-Institut National des Sciences Appliquées (INSA)-Centre National de la Recherche Scientifique (CNRS), X'Press : diffraction et hautes pressions (NEEL - X'Press), Université d'Artois (UA)-Centrale Lille-Institut de Chimie du CNRS (INC)-Université de Lille-Centre National de la Recherche Scientifique (CNRS)-Université d'Artois (UA)-Centrale Lille-Institut de Chimie du CNRS (INC)-Université de Lille-Centre National de la Recherche Scientifique (CNRS)
Jazyk: angličtina
Rok vydání: 2016
Předmět:
Zdroj: European Microscopy Congress 2016
European Microscopy Congress 2016, Aug 2016, Lyon, France. ⟨10.1002/9783527808465.EMC2016.6316⟩
DOI: 10.1002/9783527808465.EMC2016.6316⟩
Popis: International audience; Oxides in the Ln2O3-MO3 (M = Mo and W) system are of significant technological interest for their laser applications [1], ionic conduction [2], catalytic [3] and ferroelectric [4] properties. The La2O3-WO3 phase diagram has been studied by a number of groups [5–7], but little detailed crystallographic information was reported due to the lack of good single crystals. Some of the reported compositions have not been appropriately characterized. Recently, the structures of La2WO6, La18W10O57 and La10W2O21 were solved using X-ray powder diffraction (XRPD) [8–10].For the La6W2O15 compound phase transitions at 630 and 930 °C have been reported [1–3]. The structure of the high temperature phase α-La6W2O15 was determined ab-initio by XRPD [11]. The lower-temperature forms β and γ, however, couldn't be determined due to the large number of reflections in the X-ray powder diffraction pattern and the relatively low symmetry of the system. The existing literature on γ-La6W2O15 only relates two sets of unit cell parameters [5–6], that almost match the XRPD pattern of γ-La6W2O15, but some weak peaks remain without indexation and can't be explained by the presence of any impurity.Here we present the structure solution using transmission electron microscopy of the complex structure of γ-La6W2O15. From zone axis precession electron diffraction the unit cell was determined to be monoclinic with cell parameters a=1.57 nm, b=1.21 nm, c=1.57 nm, β=110°. As an example, the [100] zone axis is presented on figure 1. Due to the low symmetry of the crystal system and the large unit cell, a huge number of reflections needed to be acquired, so that electron diffraction tomography was used to record the intensities. The cation positions were obtained but the distribution of the cations on the sites was not evident. Z-contrast imaging showed that disorder on some cationic sites has to be considered (fig.2).
Databáze: OpenAIRE
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