Ab Initio Study of Ga-stabilized δ-Pu Bulk and Surfaces

摘要

The high-temperature face-centered-cubic phase of plutonium (Pu) (the 8-phase; exists at 600 K) is ductile and malleable. However in order to stabilize the 8-phase to ambient temperatures (typically 300 K), it must be alloyed with impurities such as gallium (Ga) or aluminum, making it suitable for technological applications. With as low as 1 atomic percent, Ga can stabilize the 8-phase and it is known that Ga occupies a 8-Pu fcc lattice site. The negative thermal expansion that is seen in unalloyed δ-Pu disappears with the addition of Ga. Therefore, such impurities may affect the structural and electronic properties of the material and a thorough understanding of the effects of Ga impurities on the physical properties of δ-Pu is necessary for the bulk and surfaces. Also it has been observed that the presence of Ga in δ-Pu makes it more corrosion-resistant in comparison to unalloyed Pu. Ab initio modeling allows us to gain atomistic insights into the processes that drive the interaction of the Ga impurities within the δ-Pu lattice and the effects of Ga on the interaction of the δ-Pu surfaces with common environmental gases such as oxygen, hydrogen, and water.