Atomic topology and electronic structure of a melt-spun Al92U8 metallic glass

• Published in: Computational and theoretical chemistry 2014-05, Vol.1036, p.16-21
• Main Authors: Antipas, G.S.E., Mangiorou, E.
• Format: Article
• Language: English
• Subjects: Actinides; Al92U8 metallic glass; Density functional theory; Electronic structure
• ISSN: 2210-271X
• DOI: 10.1016/j.comptc.2014.03.009

[Display omitted] •U centers promoted covalent bonding with the majority of the coordinated surface Al atoms.•U engaged its valence f orbitals towards HOMO formation only when occupying a cluster center.•Cohesion of U-centered clusters was high, owing to 5f, 6d and 7s interactions with Al-t1u.•Charge was concentrated mainly between the Al species, promoting metallic bonding.•Charge was depleted around U atoms located in the periphery of Al-centered clusters. The atomic topology and electronic structure of an exotic Al92U8 glass was studied on the basis of a Reverse Monte Carlo (RMC) supercell generated from experimental total scattering XRD and EXAFS spectra. Analysis revealed that the material is a fundamentally dense structure which may be described on the basis of select atomic clusters. The most representative such clusters were selected on the basis of the atomic pair correlation statistics along the radial direction of the RMC supercell. Al-centered cluster coordination by matrix elements was between 11 and 13 while U centers were principally coordinated by 17 Al atoms. The locus of the highest concentration of 13-fold coordinated clusters was the region up to a radial distance of 3Å from the RMC simulation box origin; similarly, the most representative U-centered cluster was within the radial region of up to 2Å from the RMC box origin. The isolated clusters were also studied by Density Functional Theory (DFT) and decomposition of their binding energies indicated that U centers achieved marginally higher cohesion compared to Al, largely due to increased molecular orbitals interactions between α-valence U-5f, U-6d and U-7s populations with surface Al-t1u. The U centers also showed pronounced spin mixing close to the Fermi energy, where their spin-up density largely contributed to highest occupied and lowest unoccupied molecular orbitals (HOMO and LUMO, respectively).