Influence of the method of preparation on Yb₂O₃ hydration

Abstract

Preliminary studies have shown that in order to achieve the complete removal of the uptaken CO₂ and H₂O from a ytterbium oxide aged in air, thermal activation up to 1173 K is required. Parallel studies have shown that bulk hydration of Yb₂O₃ does occur, the CO₂ acting as a kinetic inhibitor. The above results refer to a Yb₂O₃ prepared in our laboratory from hydroxicarbonate-like phases. In the present work, the influence of the preparation method on the hydration process is examined, by extending the study to two additional samples, a standard commercial one and another obtained by calcining a ytterbium oxalate. It is shown that the intensity of the hydration reaction depends strongly on the method of preparation. Certain applications of 4f oxides, such as their use as transition metal supports, involve thermochemical processes which may alter drastically the initial texture of the ytterbia from the oxalate. It makes this sample less useful although its initial specific surface area is high.