Regensburg 2007 – wissenschaftliches Programm
Bereiche | Tage | Auswahl | Suche | Downloads | Hilfe
MM: Fachverband Metall- und Materialphysik
MM 28: Intermetallic phases I
MM 28.3: Vortrag
Donnerstag, 29. März 2007, 10:45–11:00, H16
Prediction of stable long-period superstructures in Cu-Pd, Ag-Pd and Au-Pd within a first-principles approach — •Stefan Bärthlein1, Elke Winning1, Gus Hart2, Alex Zunger3, and Stefan Müller1 — 1Festkörperphysik, Universität Erlangen-Nürnberg, Staudtstr. 7, D-91058 Erlangen — 2Department of Physics and Astronomy, Brigham Young University, Provo, Utah 84602 — 3National Renewable Energy Laboratory, Golden, Colorado 80401
One- and two-dimensional long-period superstructures (LPS), based on the L12 substructure, are systematically investigated for the noble metal-palladium alloys Cu-Pd, Ag-Pd and Au-Pd with first-principles methods. Notwithstanding the fact that the experimental phase diagrams of these systems yield totally different features, quite similar behaviour with respect to formation of low temperature ordered LPS-phases (Cu3Pd: LPS 3 [1], Ag3Pd: LPS 3, Au3Pd: LPS 2; {Cu, Au}Pd3: L12, AgPd3: not a ground state) is predicted. As a lever between via LDA obtained formation enthalpies and a thorough ground state scan, the cluster expansion method in conjunction with a genetic algorithm [2] provides adequate means for the extraction of effective interactions, which also allow for an enhanced ground state scan in the configurational space of LPS structures. As a result, the sequences and energetical hierarchies for stable LPSs in Cu-Pd, Ag-Pd and Au-Pd are predicted and compared to conclusions based on an ANNNI-approach. (Supported by DFG.)
[1] Stefan Bärthlein et al., J. Phys.: Fast Track Comm., accepted (2006)
[2] Gus L. W. Hart et al., Nature Materials 4 391 (2005)