Raman, XRD and microscopic investigations on CeO2-Lu2O3 and CeO2-SC2O3 systems:: A sub-solidus phase evolution study

A sub-solidus phase evolution study was done in CeO2-Sc2O3 and CeO2-Lu2O3 systems under slow-cooled conditions from 1400 degrees C. Long-range order probing of X-ray diffraction technique is utilized in conjunction with the ability of Raman spectroscopy to detect the changes in local co-ordination. Lu2O3 showed solubility of 30 mol% in CeO2, thus forming an anion deficient fluorite-type (F-type) solid solution, whereas Sc2O3 did not show any discernible solubility. A biphasic region (F+C) was unequivocally detected by Raman spectroscopy in Ce1-xLuxO2-x/2 (0.4 <= x <= 0.9) and in Ce1-xScxO2-x/2 (0.1 <= x <= 0.9) systems. Raman spectroscopy was valuable in studying these systems since oxygen vacancies are created on doping RE2O3 into ceria and Raman spectroscopy is very much sensitive to oxygen polarizability and local coordination. Back scattered images collected on representative compositions support the above-mentioned results. (C) 2008 Elsevier Inc. All rights reserved.