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Structure of Cs0.5[Nb2.5W2.5O14] analysed by focal-series reconstruction and crystallographic image processing / Juri Barthel in Acta materialia, Vol. 58 N° 10 (Juin 2010) 

Public ISBD [article]  in Acta materialia > Vol. 58 N° 10 (Juin 2010) . - pp. 3764–3772 Titre : Structure of Cs0.5[Nb2.5W2.5O14] analysed by focal-series reconstruction and crystallographic image processing Type de document : texte imprimé Auteurs : Juri Barthel, Auteur ; Thomas E. Weirich, Auteur ; Gerhard Cox, Auteur Année de publication : 2011 Article en page(s) : pp. 3764–3772 Note générale : Métallurgie Langues : Anglais (eng) Mots-clés : High-resolution  transmission  electron  microscopy  (HRTEM)  Focal-series  reconstruction  Crystallographic  image  processing  (CIP)  Density  functional  theory  (DFT) Résumé : The structure of the oxygen sub-lattice in Cs0.5[Nb2.5W2.5O14] is investigated for the first time by advanced electron-optical methods. Since Cs0.5[Nb2.5W2.5O14] resembles the crystal structure of the so-called M1 phase of Mo–V–Nb–Te–O, which is the best catalyst for the selective oxidation of propane to acrylic acid, the structure analysis of the oxygen sub-lattice can contribute substantially to a better understanding of this catalytic process. The so far only partially known structure of the complex metal oxide Cs0.5[Nb2.5W2.5O14] is investigated by combining modern methods of high-resolution transmission electron microscopy with crystallographic image processing techniques. Average atom positions in the a–b plane are determined from the phase of the exit-plane wave function, which was numerically reconstructed from a focal series of spherical-aberration-corrected electron micrographs. The experimentally determined atom positions agree well with a structure model obtained by first-principles calculations for the underlying M5O14 (M = Nb, W) framework. Moreover, several deviations from the periodic structure, which may influence the catalytic properties of the structurally similar M1 phase, are observed. The obtained results demonstrate that aberration-corrected high-resolution transmission electron microscopy is a reliable alternative for the analysis of periodic structures, in particular when traditional methods for crystallographic structure determination like XRD or neutron diffraction cannot be applied. DEWEY : 669 ISSN : 1359-6454 En ligne : http://www.sciencedirect.com/science/article/pii/S1359645410001618 [article] Structure of Cs0.5[Nb2.5W2.5O14] analysed by focal-series reconstruction and crystallographic image processing [texte imprimé] / Juri Barthel, Auteur ; Thomas E. Weirich, Auteur ; Gerhard Cox, Auteur . - 2011 . - pp. 3764–3772. Métallurgie Langues : Anglais (eng) in Acta materialia > Vol. 58 N° 10 (Juin 2010) . - pp. 3764–3772 Mots-clés : High-resolution  transmission  electron  microscopy  (HRTEM)  Focal-series  reconstruction  Crystallographic  image  processing  (CIP)  Density  functional  theory  (DFT) Résumé : The structure of the oxygen sub-lattice in Cs0.5[Nb2.5W2.5O14] is investigated for the first time by advanced electron-optical methods. Since Cs0.5[Nb2.5W2.5O14] resembles the crystal structure of the so-called M1 phase of Mo–V–Nb–Te–O, which is the best catalyst for the selective oxidation of propane to acrylic acid, the structure analysis of the oxygen sub-lattice can contribute substantially to a better understanding of this catalytic process. The so far only partially known structure of the complex metal oxide Cs0.5[Nb2.5W2.5O14] is investigated by combining modern methods of high-resolution transmission electron microscopy with crystallographic image processing techniques. Average atom positions in the a–b plane are determined from the phase of the exit-plane wave function, which was numerically reconstructed from a focal series of spherical-aberration-corrected electron micrographs. The experimentally determined atom positions agree well with a structure model obtained by first-principles calculations for the underlying M5O14 (M = Nb, W) framework. Moreover, several deviations from the periodic structure, which may influence the catalytic properties of the structurally similar M1 phase, are observed. The obtained results demonstrate that aberration-corrected high-resolution transmission electron microscopy is a reliable alternative for the analysis of periodic structures, in particular when traditional methods for crystallographic structure determination like XRD or neutron diffraction cannot be applied. DEWEY : 669 ISSN : 1359-6454 En ligne : http://www.sciencedirect.com/science/article/pii/S1359645410001618