Mechanochemical synthesis of crystalline U(vi) triperoxide solids

Abstract

Mechanochemical reactivity of uranium trioxide (UO₃) in the presence of solid metal peroxides resulted in the formation of crystalline uranyl triperoxide phases, m₃₀-UO₃–Li₂O₂ and m₁₅-UO₃–Na₂O₂. Powder X-ray diffraction patterns of m₃₀-UO₃–Li₂O₂ and m₁₅-UO₃–Na₂O₂ corresponded to [UO₂(O₂)₃]₁₂[(UO₂(OH)₄)Li₁₆(H₂O)₂₈]₃·Li₆[H₂O]₂₆ and Na₄[UO₂(O₂)₃]·9H₂O compounds, respectively. Recrystallization of the solid phases in water after grinding resulted in the formation of uranyl carbonate mineral phases, such as čejkaite Na₄[UO₂(CO₃)₃]. This study demonstrated the first solvent-free synthetic pathway to uranyl triperoxide solids that avoid generation of radioactive liquid waste.