LEMOINE, Kévin; MOURY, Romain; DURAND, Etienne; ARROYO-DE DOMPABLO, Elena; MORÁN, Emilio; LEBLANC, Marc; HÉMON-RIBAUD, Annie; GRENECHE, Jean-Marc; GALVEN, Cyrille; GUNES, Veyis; LHOSTE, Jérôme; MAISONNEUVE, Vincent

doi:10.1021/acs.cgd.0c01279

Métadonnées

Afficher la notice complète

Licence d’utilisation du document

LEMOINE, Kévin
Institut des Molécules et Matériaux du Mans [IMMM]

MOURY, Romain
Institut des Molécules et Matériaux du Mans [IMMM]

DURAND, Etienne
Institut de Chimie de la Matière Condensée de Bordeaux [ICMCB]

Langue

Article de revue

Ce document a été publié dans

Crystal Growth & Design. 2021-02-03, vol. 21, n° 2, p. 935-945

American Chemical Society

Résumé en anglais

Metal fluorides with 3D open structures, pyrochlore (pyr) or hexagonal tungsten bronze (HTB), are promising materials as positive electrodes for rechargeable batteries or catalysts. Herein, we have developed a two-step synthesis procedure to obtain new anhydrous mixed-metal-cation fluorides crystallizing in the pyrochlore structure. The first step consists of preparing mixed-metal ammonium fluorides (NH4)M2+Fe3+F6 (M = Mn, Fe, Co Ni) using different synthesis strategies. For M = Mn, three allotropic varieties of (NH4)Mn2+Fe3+F6 are obtained; two phases adopt the expected pyrochlore network with either the cubic Fm3̅m or the orthorhombic Pnma space group, and the third phase exhibits a 3D network with narrow pseudotriangular cavities. 57Fe Mössbauer spectrometry indicates that the crystal structures are governed by the Fe3+/Mn2+ cationic order or disorder. The second step is a topotactic oxidation of pyr-(NH4)M2+Fe3+F6 under a molecular F2 flow. To better understand the reaction mechanism, the topotactic oxidation was followed by thermogravimetry, XRD, FTIR, and Mössbauer spectrometry. The successful synthesis of the first anhydrous pyr-M3+0.5Fe0.5F3 provides a new route to prepare anhydrous mixed-metal fluorides pyrochlore with empty cavities of the open framework.< Réduire

Mots clés en anglais

Chemical structure

Anions

Oxidation

Transition metals

Cations

Métadonnées

Licence d’utilisation du document

First mixed-metal fluoride pyrochlores obtained by topotactic oxidation of ammonium fluorides under F2 gas

Langue

Ce document a été publié dans

Résumé en anglais

Mots clés en anglais

DOI

Origine

Unités de recherche