In-situ crystallization of lanthanide titanate stannate (Ln2TiSnO7) pyrochlore in glass: A glass-ceramic system for potential nuclear waste sequestration

Abstract

Ln 2TiSnO7 (Ln = Nd-Er) pyrochlore glass-ceramics are produced by calcining the pelletized oxide mixture and sodium aluminoborosilicate glass precursor at 1200 °C for 4 h. The ceramic Ln-Ti-Sn oxide mixture is prepared by a soft chemistry route to enhance reactant reactivity and product homogeneity. X-ray diffraction, Raman spectroscopy, and electron microscopy techniques are used to confirm the formation of the pyrochlore structure in glass. The cell parameters of the pyrochlores by Le Bail fitting are consistent with the calculated data. The variation of the lanthanide on pyrochlore A-site has insignificant effect on the Raman F 2 g mode ∼ 310 cm−1, but has an apparent influence on A 1 g mode ∼ 504–512 cm−1, which gradually shifts to low frequencies with increasing Ln 3+ionic radii. The average sizes of the pyrochlore crystals are ∼ 0.31–0.62 μm, which are uniformly distributed in glass phase. These Ln 2TiSnO7 pyrochlore glass-ceramics with mixed elements on B-site, possessing high radiation tolerance feature due to the presence of Sn, could be used as nuclear waste forms. Crown Copyright © 2023 Published by Elsevier B.V. All rights reserved.