PHASE RELATIONSHIPS IN AMERICIUM-OXYGEN SYSTEM

Phase relations in the americium-oxygen system between 1·50 < O/Am < 2·00 were studied using Guinier and Debye diffraction methods on quenched and annealed samples. The cubic Am2O3 phase was found to be capable of dissolving excess oxygen and exists, at room temperature, over a wide range of stoichiometry. The upper boundary of this phase occurs at about AmO1·67, Between this composition and AmO2·00 at least one other intermediate phase is thought to exist. Evidence was found for what is believed to be a new Am2O3 phase which is probably monoclinic (B-type rare earth sesquioxide structure). The likelihood for the existence of this phase, as well as the cubic and hexagonal Am2O3 phases, is discussed in terms of a lanthanide/actinide oxide analogy based on considerations of ionic radii. A homologous series of substoichiometric ordered intermediate phases was not observed. The lack of such phases in this system is thought to be influenced by self-induced radiation damage caused by the alpha decay of americium-241. © 1968.