XRD and Raman Spectroscopy Study of Fe solubility in Cerium Oxide

The solubility of Fe in CeO 2 was investigated for 3-50 mol% Fe. Powders were synthesized by the Pechini method in air. Raman spectroscopy and lattice parameter analysis revealed that the solubility limit of Fe in CeO 2 is less than 3 mol% for the present preparation conditions. The low solubility limit was rationalized in terms of the much smaller ionic radius of Fe versus Ce. As a consequence, an approach to increase the Fe radii size through annealing in reducing conditions (humidified H 2 at 1100 ℃) was attempted. In this case, the more stable CeFeO 3 phase was observed by XRD, thereby indicating difficulty in obtaining Fe doped CeO 2 under reducing conditions, as well.