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Communication Dans Un Congrès Année : 2023

Unraveling the structure of TlNbOx bronze oxide by atomic STEM and STEM-EDX

M. Aouine
T. Minh Nha Le
  • Fonction : Auteur
Y. Lefkir
  • Fonction : Auteur
S. Reynaud
  • Fonction : Auteur

Résumé

The best catalyst for the ammoxidation of propane is presently based on a crystalline Mo-V-Nb mixed oxide, called M1 phase, with a complex bronze-type structure [1]. In addition to vanadium and molybdenum, it contains systematically a lone pair electrons element. In the structure of the M1 phase Mo, V and Nb are hexacoordinated forming corner-sharing Mo(V,Nb)O6 octahedra that delimits hexagonal and heptagonal channels aligned in the 001 direction. The search for similar phases showed that rubidium or thallium niobate with compatible framework could be good candidates. In the present work, such new compounds were successfully synthesized using a microwave-assisted hydrothermal method. Among these new compounds, a new niobate with a similar structure was obtained, thallium niobate, Tl7Nb39O101, which to the best of our knowledge had never been detected before. Its relatively complex structure was determined by X-ray diffraction on the basis of precious information obtained by advanced transmission electron microscopy work, e.g. STEM imaging (300 kV FEI/TFS Titan ETEM), aberration-corrected STEM imaging and STEM-EDX atomic mapping (200 kV JEOL Neo ARM equipped with a Centurio Large Angle SDD-EDS detector). In particular, ADF, e-ABF [2] and BF micrographs were suitably combined in order to produce bright-field type atomic images revealing the location of oxygen positions and possibly required Nb interstitials cations insuring the electroneutrality of the solid. Figure 1 illustrates the results still under analysis in order to complete the structural investigation trhough a combined TEM / DRX Riteveld refinement approach [3]. Références/References : [1] J.L. Dubois, G.S. Patience, J.M.M. Millet, "Nanotechnology in catalysis, applications in the chemical industry, energy development and environmental protection", B. Sels, M. van de Voorde (Ed.), Wiley-VCH, Weinheim, (2017) 503. [2] S.D. Findlay, Y. Kohno, L.A. Cardamone, Y. Ikuhara, N. Shibata, Ultramicroscopy 136 (2014) 41. [3] Thanks are due to the CLYM (www.clym.fr) for the access to the microscopes.
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Dates et versions

hal-04229750 , version 1 (05-10-2023)

Identifiants

  • HAL Id : hal-04229750 , version 1

Citer

M. Aouine, T. Minh Nha Le, Y. Lefkir, S. Reynaud, J. Millet, et al.. Unraveling the structure of TlNbOx bronze oxide by atomic STEM and STEM-EDX. 18ème Colloque de la SFµ, Jul 2023, Rouen, France. ⟨hal-04229750⟩
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