Magnetic Susceptibilities of Cubic UO2+x at High Temperature

Abstract

Magnetic Susceptibilites of cubic UO_2+x (x=0.00₃–0.24₈) were measured over the temperature range between 77°K and 1100°K. Susceptibilities of UO₂ single crystals follow the Curie-Weiss law with a high value of the Weiss constant (-22₀°K). The phase boundaries between one phase (UO_2+x) and two phases (UO_2+x and U₄O_9-y) in helium atmosphere were obtained from the breaks in the inverse susceptibility-temperature relations of the intermediate oxides from UO₂ up to U₄O₉. The susceptibility data of UO₂ and U₄O₉ were discussed in terms of the ground state configuration f² perturbed by the crystalline field, in connection with the results of neutron diffraction.