J. Phys. IV France 04 (1994) C9-117-C9-120
Nucleation in xerogels of the SiO2-Al2O3-ZnO-Cr2O3 system studied by EXAFS spectroscopyF. Keller-Besrest1 and S. Benazeth2, 3
1 Laboratoire de Biomathématiques et Physique, UFR de Pharmacie, Université Paris V, 4 Avenue de l'Observatoire, 75270 Paris, France
2 Laboratoire de Chimie-Physique Minérale et Bioinorganique, Faculté de Pharmacie, Université Paris XI, 92296 Chatenay Malabry, France
3 LURE, Bat 209D, Centre Universitaire d'Orsay, 91405 Orsay, France
During nucleation and crystallisation processes from xerogels of the system studied, crystallites Zn(A11-xCrx)2O4 are formed. Analysis by EXAFS spectroscopy at the Zn K-edge of gels with different Cr concentration and thermal treatments compared to that of reference compounds ZnA12O4 and ZnCr2O4 allow to identify the nature of the nucleating precursors and the phases formed in the crystallization steps.The formation of ZnCr2O4 nanocrystallites during the first steps of nucleation cannot be confirmed, while for high temperature treatments, the x value close to 0 as previously obtained is verified.
© EDP Sciences 1994