Cerium oxidation during leaching of CeYSiAlO glass

The chemical stability of a CeYSiAlO glass was examined after leaching with bidistilled water (autoclave: T=90$^\circ$) during 1 month. The initial $S/V$ ratio was approximately 0.06 cm$⁻¹$ and the pH was free to drift during the experiments (initial pH $\simeq$ 5.5). The leached samples were analyzed using scanning electron microscopy coupled with energy disperse X-ray spectrometer, X-ray photoelectron spectrometry and X-ray diffraction. Dissolution kinetics were also followed by inductively coupled plasma mass spectrometry and spectrophotometry analyses of the liquid medium. The results indicate that Ce is oxidized during leaching which results in the formation of a thick amorphous Ce(IV)-containing layer, possibly CeO$_2$ with Y and probably −OH (and/or H$_2$O) species. It is hypothesized that the low solubility of Ce(IV) oxide (and/or hydroxide) is mainly responsible for the formation of this layer, thus, preventing the release of Y and Ce and to a lesser extent of Si and Al after a few days of leaching.