Radium peroxide is expected to have the molecular
formula of RaO2 and the molecular weight of
258.0242 g/mol. It could be prepared by the reaction of
Ra(OH)2 with sodium peroxide in a cold solution:
Ra(OH)2+Na2O2→RaO2+2NaOH
The octahydrate is the expected product but there is
no record of this compound ever having been prepared
because of the lack of interest by industry and academia.
RaO2 is expected to have a tetragonal structure but it has not been measured. Whether the Ra2+ cation is too large to fit into the Ca2C structure, like the Sr and Ba homologues, remains unknown.