Temperature-dependent growth shapes of Ni nanoclusters on NiAl(110).
نویسندگان
چکیده
Scanning tunneling microscopy studies reveal that two-dimensional nanoscale Ni islands formed by deposition of Ni on NiAl(110) between 200-400 K exhibit far-from-equilibrium growth shapes which change systematically with temperature. Island structure reflects the two types of adsorption sites available for Ni adatoms, and island shapes are controlled by the details of adatom diffusion along island edges accounting for numerous local configurations. The temperature dependence of the island shapes is captured and elucidated by kinetic Monte Carlo simulation of a realistic atomistic-level multisite lattice-gas model incorporating precise diffusion barriers. These barriers are obtained by utilizing density functional theory to probe energetics not just at adsorption sites but also at transition states for diffusion. This success demonstrates a capability for predictive atomistic-level modeling of nanocluster formation and shape selection in systems that have a high level of energetic and kinetic complexity.
منابع مشابه
Monte Carlo modeling of low-index surfaces in stoichiometric and Ni-rich NiAl
The structure and chemical composition of low-index surfaces of NiAl are investigated by grand canonical Monte Carlo simulations. Atomic interactions in NiAl are modeled by an embedded-atom potential fit to experimental and first-principles data. The simulations are performed at the temperature of 1200 K for the stoichiometric and two Ni-rich bulk compositions. For the ~110! surface, the top su...
متن کاملSurface energy and the early stages of oxidation of NiAl(110)
We have studied the (110) surface of NiAl, an ordered alloy of B2 structure, using a plane-wave pseudopotential method. The clean surface and several oxidized surfaces were investigated, with oxygen coverages up to 1.5 ML (1 ML = 1 O-atom per surface metal atom). In order to compare the energies of the oxidized structures, which comprise different numbers of metal and oxygen atoms, one has to t...
متن کاملFirst-principles characterization of Ni diffusion kinetics in -NiAl
First-principles density functional theory calculations are performed to examine five postulated diffusion mechanisms for Ni in NiAl: next-nearest-neighbor NNN jumps, the triple defect mechanism, and three variants of the six-jump cycle. In contrast to most previous theoretical work, which employed empirical interatomic potentials, we provide a more accurate nonempirical description of the mech...
متن کاملSelf-assembly of metal nanostructures on binary alloy surfaces.
Deposition of metals on binary alloy surfaces offers new possibilities for guiding the formation of functional metal nanostructures. This idea is explored with scanning tunneling microscopy studies and atomistic-level analysis and modeling of nonequilibrium island formation. For Au/NiAl(110), complex monolayer structures are found and compared with the simple fcc(110) bilayer structure recently...
متن کاملKinetics of facile bilayer island formation at low temperature: Ag/NiAl(110).
Facile nucleation and growth of bilayer Ag(110) islands on NiAl(110) is observed by STM for Ag deposition at temperatures as low as 127 K. Density functional theory analysis for supported Ag films determines adatom adsorption energies (which favor bilayer islands), interaction energies, and diffusion barriers. Analysis of an atomistic lattice-gas model incorporating these energies elucidates th...
متن کاملذخیره در منابع من
با ذخیره ی این منبع در منابع من، دسترسی به آن را برای استفاده های بعدی آسان تر کنید
برای دانلود متن کامل این مقاله و بیش از 32 میلیون مقاله دیگر ابتدا ثبت نام کنید
ثبت ناماگر عضو سایت هستید لطفا وارد حساب کاربری خود شوید
ورودعنوان ژورنال:
- The Journal of chemical physics
دوره 135 8 شماره
صفحات -
تاریخ انتشار 2011