Effects of UO3 on the Structure, Thermal and Chemical Stability of Borosilicate Glass Matrix

Tolnai, I. and Osán, J. and Pinakidou, F. and Kovács, Zs. and Fábián, M. (2024) Effects of UO3 on the Structure, Thermal and Chemical Stability of Borosilicate Glass Matrix. JOURNAL OF NON-CRYSTALLINE SOLIDS, 637. No.-123054. ISSN 0022-3093 (print); 1873-4812 (online)

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Abstract

The glass matrix of composition: 55SiO2-10B2O3-25Na2O-5BaO-5ZrO2 was incorporated with 10 to 40 wt.% of UO3 by melt quenching technique. Neutron diffraction and Reverse Monte Carlo simulations revealed that the borosilicate network consists of SiO4, BO3 and BO4 units; upon adding 10 % UO3 the B-O coordination increases from 3.08 to 3.86 and subsequently decreases with a further in increase in UO3 content. X-ray absorption near edge and Extended X-ray absorption studies revealed that U exist in 5+ and 6+ oxidation states with U-O coordination numbers of 8 and 6 respectively. The thermal stability decreases and weight losses increases with the addition of UO3 in the glass matrix, the sample with 30 wt.% UO3 has thermal stability comparable to that of matrix glass and exhibits lowest dissolution rate in water. Nanoindentation measurements showed that the microstructure of sample with 30 wt.% UO3 is 11% weaker than that of the matrix glass.

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