Dresden 2003 – wissenschaftliches Programm
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M: Metallphysik
M 30: Nanoskalige Materialien IV
M 30.1: Vortrag
Mittwoch, 26. März 2003, 16:30–16:45, IFW A
Alloying on the Nanoscale — •Sibylle Gemming1 and Michael Schreiber1,2 — 1Institut für Physik, Technische Universität, D-09107 Chemnitz — 2School of Engineering and Science, International University Bremen, D-28725 Bremen
The miscibility of Ag and Au is limited in the bulk phase. However, density-functional band-structure calculations indicate that alloying can take place in nano-sized objects. Three different structural modifications of two-shell nanowires have been investigated by density-functional calculations, using the plane-wave band-structure code ABINIT [1]. As discovered previously for pure Ag and Au nanowires, all investigated structures are stable local minima of the cohesive energy. The nanowires and flat dense-packed surfaces are of comparable energy with respect to pure bulk phases. The dense-packing effects at the gold wire surface, which stabilised chiral wires of pure Au [2], also prevails for Ag contents less than 50%. An No-dqisland of stabilityNo-dq is obtained for Ag contents of 10% to 30 %, with thinner wires favouring the higher Ag contents. The present investigation elucidates that an optimum balance of strain states within the two shells drives the alloying process and favours gold-coated Ag chains over the pure wires. [1] The ABINIT code is a common project of the Universite Catholique de Louvain, Corning inc., and other contributers. [2] E. Tosatti, S. Prestipino, S. Köstlmeier, A. dal Corso, F. Di Tolla, Science 291 (2001) 288.