First-principles calculations of stability of δ-Pu-Am alloys

First-principles methods are employed to study the ground-state properties of Pu-Am systems. Calculated density of delta-Pu-100-Am-c(c) alloys (c = 30 at.%) agrees well with the experimental data. The paramagnetic (PM) --> antiferromagnetic (AF) transition temperature (T-c) of Pu-100-Am-c(c) alloys is calculated by the Monte Carlo technique. By introducing Am into the system, one could lower T-c from similar to548 K (pure Pu) to 372 K (Pu70Am30). We also found that, contrary to pure Pu where this transition destabilizes the delta-phase, Pu3Am compound remains stable in the antiferromagnetic phase that correlates with recent discovery of a Curie-Weiss behavior in Pu-100-Am-c(c) system at c approximate to 24 at.%. (C) 2004 Elsevier B.V. All rights reserved.