Sol–gel obtained silicophosphates as materials to retain caesium at high temperatures

Abstract

Silicate-based and silicophosphate-based compounds containing caesium have been synthesized by a sol–gel process. The structural changes induced by thermal treatment have been studied by XRD, XRF, DRIFTS, thermogravimetric and XPS analyses. The solids crystallise upon heating and the behaviour of the crystallisation process depends on the P-content. A partial loss of caesium is observed from 900 °C in the case of the sample with no or too low P-content, but for the Cs–SiPO solids with higher P-content, no Cs or P loss are observed. It seems that there exists a threshold of P-content, above which the quantity of P is sufficient to retain caesium at least up to 900 °C. This work opens a new, promising way in potential waste confinement matrix research.