Structural Investigation of Mixed Nitrided Galloaluminophosphates “AlGaPON” by EELS, XAS, and XPS Spectroscopies

✍ Scribed by S. Delsarte; V. Serin; A.-M. Flank; F. Villain; P. Grange

• Publisher: Elsevier Science
• Year: 2002
• Tongue: English
• Weight: 611 KB
• Volume: 163
• Category: Article
• ISSN: 0022-4596
• DOI: 10.1006/jssc.2001.9389

✦ Synopsis

Amorphous nitrided galloaluminophosphates 99AlGaPON:: catalysts with nitrogen contents varying from 0 to 23.3 wt% N were obtained by nitriding an Al 0.5 Ga 0.5 PO 4 precursor under ammonia 6ow at 7503C 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 5rst-coordination spheres of P, Ga, and Al atoms are modi5ed by nitridation. In particular, the comparison of the P XANES spectra recorded on 99AlGaPON:: and on a PON phosphorus oxynitride (reference of mixed PO 2 N 2 tetrahedra) reveals that mainly PO 2 N 2 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.