Mechanochemical synthesis of crystalline U(vi) triperoxide solids†
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.