An investigation in the americium oxide system

Phase behavior of PuO2−x with addition of 9% Am

“…The transition temperature of (Pu 0.91 Am 0.09 )O 2−x from single phase to two phase (γ → γ 1 + γ 2 : about 950 • C) was higher than that of the Pu-O system (about 650 • C) [5]. This transition temperature of (Pu 0.91 Am 0.09 )O 2−x corresponded roughly to the transition temperature of the Am-O system (about 1050 • C) [6], rather than the Pu-O system [5]. Morimoto et al [10] investigated the phase transition temperature of a single fluorite phase to a two-phase fluorite for (Pu 0.94 Am 0.06 )O 2−x .…”

“…There were also indications of a phase transition at about 300 • C throughout the range of investigated O/M ratios. In this temperature, the phase transition from high temperature bcc to low temperature bcc (C → C ) might take place for (Pu 0.91 Am 0.09 )O 2−x analogous to Pu-O and Am-O systems [4][5][6]. In addition, there were also indications of phase transitions at about 630 • C below an O/M ratio of 1.96.…”

“…They found that there was a two-phase solid miscibility gap with a boundary of about 650 • C for O/Pu ratios between 1.70 and 1.98. Sari and Zamorani [6] measured the phase transition behavior of AmO 2−x by differential thermal analysis (DTA). They found that while the profile of the phase diagram for the Am-O system was similar to that of the Pu-O system, phase transition temperatures from the single phase to two phases of the Am-O system were higher than those corresponding to the Pu-O system.…”

Oxygen Dissociation Pressures and Phase Behavior in the Transplutonium Oxides.

“…These show the formation of a bcc phase (a) These results may be compared t o a recent investigation of the system by ceramographic and DTA methods by Sari and Zamorani [7].…”

“…. a greater complexity in the 1.67-1.80 region and that the a f i e l d extends t o the 1.50 composition rather than t o 1.63 a s indicated by Sari and Zamorani [7]. Clearly, these differences 'can be resolved only by equilibrium studies over the f u l l range of composition, most importantly by high temperature diffraction methods.…”