Effect on the structure and stability of iron phosphate glass with Sb and Te-ion loading for nuclear waste storage application

Iron phosphate glass (IPG) is emerging as an alternative to the more commonly used borosilicate glass for nuclear waste vitrification. Consequently, there is an urgent need to study the effect of loading of various elements generated as waste from nuclear fission on the structure and stability of IPG. In the present work, immobilization of inactive antimony (Sb) and tellurium (Te) in IPG has been attempted via melt quench technique. Detailed studies on the structure and composition of the resultant IPG glassform have been done to ascertain the extent of individual and co-loading of Sb/Te, which can form homogenous melts without crystallization. The FTIR and Raman spectroscopic studies give insight into the change in bonding of the associated structural units on Sb/Te loading in IPG. The Fe2+/Fe3+ redox ratio and average coordination number have been determined using Mo center dot ssbauer data which gives an insight into the cohesive energy of the Sb/Te loaded IPG. The atomic scale local structure has been analysed from X-ray absorption spectroscopy (XAS) at Fe/Sb K-edge. From extensive thermal studies it has been observed that glass transition temperature (Tg) of IPG co-loaded with 10mol% Sb and 20mol% Te is higher than that of pristine IPG and they also exhibit better glass stability as well as glass forming ability. The structural change in this co-loaded sample is not drastic as verified from FTIR and Raman spectroscopy and hence proves that IPG matrix is suitable for vitrification of antimony and tellurium containing nuclear waste.