XPS investigations of lanthanum in faujasite-type zeolites

Faujasite-type zeolites containing lanthanum introduced by various techniques and in different amounts were studied by X-ray photoelectron spectroscopy to elucidate the influence of the zeolite matrix on the binding energy and the shape of the La(3d) line. The results were discussed with regard to the spectral properties of the La(3d) line in La2O3. Significant differences in the La(3d) line shapes and binding energies between La2O3 and La zeolites were ascribed to final-state effects arising from the hybridization of La final states with valence bands of different extension. The La(3d) line shape of the La zeolites investigated at elevated temperatures was found to respond to structural changes in the surface region of the samples (dehydration, ion migration, formation of highly dispersed La-O structures on extraframework sites). These were also reflected in bulkphase properties of the samples (lattice parameters, determined by X-ray diffraction