Self-propagating high-temperature synthesis of Y₂Ti₂O₇ pyrochlore and its aqueous durability

In this study, highly densified Y₂Ti₂O₇ pyrochlore waste forms were readily prepared within 5 min by self-propagating high-temperature synthesis plus quick pressing (SHS/QP). Fe₂O₃ was employed as the oxidant with Ti as the reductant. The as-prepared sample exhibits an analogous self-encapsulated morphology with Y₂Ti₂O₇ core and Fe cladding. The synthesized pyrochlore-based waste form possesses high density of 5.35 g/cm³ and Vickers hardness of 11.5 ± 0.2 GPa, as well as excellent aqueous durability. The 28 days normalized leaching rates of Y, Ti and Fe are as low as 1.07 × 10⁻⁶, 6.63 × 10⁻⁵ and 1.42 × 10⁻⁵ g m⁻² d⁻¹. - Highlights: • Highly densified Y₂Ti₂O₇ pyrochlore was prepared by SHS/QP within 5 min. • The prepared sample exhibits encapsulated structure with Y₂Ti₂O₇ core and Fe shell. • The pyrochlore waste form exhibits high density, hardness and aqueous durability.