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Microwave synthesis of an aluminum fluoride hydrate with cationic vacancies: structure, thermal stability, and acidic properties

hal.structure.identifierInstitut de Chimie de la Matière Condensée de Bordeaux [ICMCB]
dc.contributor.authorDAMBOURNET, Damien
hal.structure.identifierInstitut de Chimie de la Matière Condensée de Bordeaux [ICMCB]
dc.contributor.authorDEMOURGUES, Alain
hal.structure.identifierLaboratoire des oxydes et fluorures [LdOF ]
dc.contributor.authorMARTINEAU, Charlotte
hal.structure.identifierInstitut de Chimie de la Matière Condensée de Bordeaux [ICMCB]
dc.contributor.authorDURAND, Etienne
hal.structure.identifierInstitut de Chimie de la Matière Condensée de Bordeaux [ICMCB]
dc.contributor.authorMAJIMEL, Jérôme
hal.structure.identifierLaboratoire des oxydes et fluorures [LdOF ]
dc.contributor.authorLEGEIN, Christophe
hal.structure.identifierInstitut de recherche en ingénierie moléculaire et matériaux fonctionnels de l'université du Maine [IRIMMFUM]
hal.structure.identifierLaboratoire de physique de l'état condensé [LPEC]
dc.contributor.authorBUZARÉ, Jean-Yves
hal.structure.identifierConditions Extrêmes et Matériaux : Haute Température et Irradiation [CEMHTI]
dc.contributor.authorFAYON, Franck
hal.structure.identifierLaboratoire catalyse et spectrochimie [LCS]
dc.contributor.authorVIMONT, Alexandre
hal.structure.identifierLaboratoire catalyse et spectrochimie [LCS]
dc.contributor.authorLECLERC, Hervé
hal.structure.identifierInstitut de Chimie de la Matière Condensée de Bordeaux [ICMCB]
dc.contributor.authorTRESSAUD, Alain
dc.date.issued2008
dc.identifier.issn0897-4756
dc.description.abstractEnAluminum fluoride hydrate was synthesized by a microwave hydrothermal process. The structure derives from the ReO3 type structure, that is, the high temperature structure of α-AlF3. The cubic symmetry adopted by this compound arises from water molecules, stabilized as ligand surrounding Al3+ cations which induces cationic vacancies as revealed by Rietveld refinement. The following chemical formula Al0.82◻0.18F2.46(H2O)0.54 is supported by chemical analysis and TGA measurements. This represents the first example of aluminum vacancy compound in the Al-based fluorides chemistry. High field 27Al NMR spectroscopy enabled identification and quantification of the following species: AlF6 and AlF6−x(H2O)x with x = 1, 2, 3, and showed that vacancies are mainly surrounded by water molecules but also by a low content of fluoride ions as also evidenced by 19F NMR. The hydrogen bonding network, which takes place in the vicinity of the cationic vacancies, was characterized by FTIR and 1H NMR spectroscopies. A 2:1 complex X···H−O−H···X where X is a proton acceptor, which is related to a shift of the νsym(OH) and νasym(OH), was detected. This complex appears to be stable up to 773 K. The phase transition into the rhombohedral form occurs at around 573 K, but at such a temperature a large amount of water molecules associated to cationic vacancies still remained thanks to the 2:1 complex. The acidic properties have been revealed by pyridine and CO probe molecules. At 573 K, the solid exhibits both strong Lewis and Brønsted acidities with an equivalent number of sites providing bifunctionality. The strong acidic behavior highlights the effect of water molecules/cationic vacancies on the surface structure. Whereas the Lewis strength acidity progressively decreases with dehydration, Brønsted acidity remains strong even at 773 K.
dc.language.isoen
dc.publisherAmerican Chemical Society
dc.subject.enAluminum
dc.subject.enFluoride hydrate
dc.subject.enMicrowave synthesis
dc.subject.enInorganic chemistry
dc.title.enMicrowave synthesis of an aluminum fluoride hydrate with cationic vacancies: structure, thermal stability, and acidic properties
dc.typeArticle de revue
dc.identifier.doi10.1021/cm8023617
dc.subject.halChimie/Matériaux
bordeaux.journalChemistry of Materials
bordeaux.page7095-7106
bordeaux.volume20
bordeaux.issue22
bordeaux.peerReviewedoui
hal.identifierhal-00339896
hal.version1
hal.popularnon
hal.audienceInternationale
hal.origin.linkhttps://hal.archives-ouvertes.fr//hal-00339896v1
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