Anomalous thermodynamic properties and phase stability of delta-Pu1-xMx (M = Ga and Al) alloys from first-principles calculations

• The composition-dependent crystal structure, volume, elastic constants, and electronic structure of delta-Pu1-xMx (M = Ga and Al, 0 <= x <= 0.1) alloys are systematically studied by using first-principles EMTO-CPA calculations. It is shown that the fcc and L1(2) structures co-exist in the alloys with x <= 0.04 whereas for x > 0.04, the L1(2) structure is more and more preferable and around x = 0.1, it tends to be stabilized alone. The evaluated V similar to x of the L1(2) structure, being negative deviation from Vegard's law, turns out to be in good agreement with the experimental result. For x <= 0.04, the estimated E, G, nu, and Theta of both the fcc and L1(2) structures are in line with the measured data, whereas when x > 0.04, only those of the L1(2) structure are close to the experimental results. The electronic hybridization between Pu and M atoms is dominated by Pu for the s, d, and f states but M for the p state. The strong interactions between Pu and M atoms in the same site of the L1(2) structure should be responsible for its relative stability in the alloys withx > 0.04. The electron-phonon coupling further decreases the phase stability of delta-Pu1-xMx with increasing x.

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NATURVETENSKAP  -- Fysik (hsv//swe)

NATURAL SCIENCES  -- Physical Sciences (hsv//eng)

NATURVETENSKAP  -- Fysik -- Den kondenserade materiens fysik (hsv//swe)

NATURAL SCIENCES  -- Physical Sciences -- Condensed Matter Physics (hsv//eng)

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