Structural Investigation of Mixed Nitrided Galloaluminophosphates “AlGaPON” by EELS, XAS, and XPS Spectroscopies |
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Authors: | S Delsarte V SerinA-M Flank F VillainP Grange |
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Institution: | a Catalyse et Chimie des Matériaux Divisés, Université catholique de Louvain, Croix du Sud 2/17, 1348, Louvain-la-Neuve, Belgiqueb Centre d'Elaboration des Matériaux et d'Etudes Structurales (CEMES), 29, Rue Jeanne Marvig, 4347, 31055, Toulouse Cedex 4, Francec Laboratoire pour l'Utilisation du Rayonnement Electromagnétique (LURE), Centre Universitaire Paris-sud, 34, 91898, Orsay Cedex, Franced Laboratoire de Chimie Inorganique et Matériaux Moléculaires, Université Pierre et Marie Curie, 4 Place Jussieu, 75252, Paris, France |
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Abstract: | Amorphous nitrided galloaluminophosphates “AlGaPON” catalysts with nitrogen contents varying from 0 to 23.3 wt% N were obtained by nitriding an Al0.5Ga0.5PO4 precursor under ammonia flow at 750°C in a tubular furnace. The structural changes induced by this treatment were investigated by electron energy loss spectroscopy (EELS), X-ray absorption spectroscopy (XAS), and X-ray photoelecton spectroscopy (XPS). XANES and XPS results indicate that the first-coordination spheres of P, Ga, and Al atoms are modified by nitridation. In particular, the comparison of the P XANES spectra recorded on “AlGaPON” and on a PON phosphorus oxynitride (reference of mixed PO2N2 tetrahedra) reveals that mainly PO2N2 tetrahedra are present in highly nitrided samples. Moreover, the replacement of oxygen by nitrogen probably concerned P-O-Ga bonds rather than P-O-Al. EELS investigation reveals that the precursor is homogeneous at the used probe scale, but indicates that nitridation is accompanied by a loss of homogeneity of the material. |
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Keywords: | AlGaPON oxynitrides basic catalysts EELS XAS XPS |
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