Published online by Cambridge University Press: 09 July 2018
The interaction between interlamellar Lu(III) cations and the layered silicate structure has been studied by means of MAS-NMR, XRD and EDX. Irreversible fixation of exchangeable Lu(III) cations upon hydrothermal treatment at 300°C of Lu-saturated montmorillonite is reported, through the formation of the crystalline phase Lu2Si2O7. It is shown that the lowest temperature previously described for this reaction, 400°C, does not indicate a thermodynamic boundary. This basic solid-state finding is relevant for some clay applications such as those related to the safety of nuclear waste repositories with engineering barriers.