BEHAVIOR OF RARE-EARTH SESQUIOXIDES EXPOSED TO ATMOSPHERIC CARBON-DIOXIDE AND WATER

The behavior of the rare earth sesquioxides, when exposed to atmospheric water and carbon dioxide under ordinary conditions of temperature and pressure, is reviewed. Data corresponding to eleven samples from seven different oxides systematically investigated by x-ray diffraction (XRD), IR spectroscopy, thermogravimetry (GT) and temperature-programmed decomposition (TPD), are reported. The BET surface areas of all these samples are also given. In accordance with the results summarized, upon exposure to air, the lanthanide susquioxide all become hydrated and carbonated in bulk. In some cases, the behavior has been found to depend on the origin of the samples, which prevents the generalization of definite sequences of reactivity for the whole series of oxides.