Atomic ordering in Au-(42 to 50) at.% Pd: A diffuse scattering and first-principles investigation
2012 (English)In: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, E-ISSN 1550-235X, Vol. 85, no 1, 014204- p.Article in journal (Refereed) Published
Atomic ordering in Au-Pd alloys was studied by diffuse x-ray scattering and first-principles methods. Diffuse scattering was done of a single crystal of Au-48 at.% Pd that was aged at 703 K for 24 days. The weakly modulated short-range-order scattering exhibits diffuse maxima with an incommensurate wave vector, which can be related to a Fermi-surface nesting mechanism. From effective pair interaction parameters determined by the inverse Monte Carlo method, a one-dimensional long-period superstructure of the CH structure, LPS1, was found for AuPd. Concurrent electronic-structure calculations of the effective cluster interaction (ECI) parameters indicated the presence of another closely related superstructure, LPS2, at 0 K. At the same time, direct first-principles calculations of the total energies of the CH structure and further one-dimensional long-period superstructures predicted the stabilization of LPS4. Although the energy differences between these structures are small and a complex behavior of the effective interactions is expected due to the Fermi-surface nesting, experimental data and theoretical results both support the stabilization of a long-period superstructure of the CH structure for AuPd at 0 K. The ECI parameters determined by the screened generalized perturbation method also predicted a ground-state structure different from Au(7)Pd(5), previously obtained from cluster expansion calculations. Its energetic preference was confirmed by direct total-energy calculations.
Place, publisher, year, edition, pages
2012. Vol. 85, no 1, 014204- p.
SHORT-RANGE-ORDER, TOTAL-ENERGY CALCULATIONS, DISORDERED BINARY-ALLOYS, GOLD-PALLADIUM ALLOYS, AUGMENTED-WAVE METHOD, ELECTRON-DIFFRACTION, FERMI SURFACES, ELASTIC CONSTANTS, BASIS-SET, X-RAY
IdentifiersURN: urn:nbn:se:kth:diva-83778DOI: 10.1103/PhysRevB.85.014204ISI: 000299423600001ScopusID: 2-s2.0-84856419060OAI: oai:DiVA.org:kth-83778DiVA: diva2:513769
FunderSwedish Research Council
QC 201204032012-04-032012-02-132012-04-03Bibliographically approved