INVESTIGATION OF SOME PHASE-TRANSFORMATIONS INDUCED BY CO2-LASER IRRADIATION IN SOME RARE-EARTH-OXIDES

Binary rare-earth ceria-ytterbia and ceria-dysprosia and pure CeO2 hav e been subjected to CO2-laser irradiation. All the samples have been p repared by precipitation and controlled drying. Irradiated samples as well as the samples calcinated at 1273 K have been studied using TG-DT A, TEM and SAED, WAXS and FT-IR. Introduction of a second rare-earth o xide, like ytterbia or dysprosia led to an important increase of 'stab ility' towards the CO2-laser irradiation. Thermal investigation of the se samples revealed in fact a 'metastability' because, for the tempera tures of about 500 K, a release of oxygen has been observed. This beha viour could recommend CO2-laser irradiation as a possible alternative for activation of the oxidation catalysts.