Search results for "SPINODAL DECOMPOSITION"
showing 10 items of 76 documents
Mechanisms for the Decay of Unstable and Metastable Phases: Spinodal Decomposition, Nucleation and Late-Stage Coarsening
1989
The basic concepts on the kinetics of phase separation in alloys are introduced, and the current status of the theory is briefly reviewed. Particular emphasis is given to questions such as the conditions under which the linearized theory of spinodal decomposition is valid, the significance of spinodal curves, the possible description of coarsening in terms of power laws and structure-factor scaling, and non-equilibrium percolation phenomena.
Wetting and phase separation at surfaces
2005
We study the problem ofsurfacedirected spinodal decomposition, viz., the dynamical interplay of wetting and phase separation at surfaces. In particular, we focus on the kinetics of wetting-layer growth in a semi-infinite geometry for arbitrary surface potentials and mixture compositions. We also present representative results for phase separation in confined geometries, e.g., cylindrical pores, thin films, etc.
Surface-directed spinodal decomposition in a thin-film geometry: A computer simulation
1994
The phase separation kinetics of a two-dimensional binary mixture at critical composition confined between (one-dimensional) straight walls which preferentially attract one component of the mixture is studied for a wide range of distancesD between the walls. Following earlier related work on semiinfinite systems, two choices of surface forces at the walls are considered, one corresponding to an incompletely wet state of the walls, the other to a completely wet state (forD→∞). The nonlinear Cahn-Hilliard-type equation, supplemented with appropriate boundary conditions which account for the presence of surfaces, is replaced by a discrete equivalent and integrated numerically. Starting from a …
A distributed dynamic load balancer and its implementation on multi-transputer systems for molecular dynamics simulation
1990
Abstract A new and efficient approach is described to the dynamic load-balancing problem which is central in concurrent computing. A transputer-based implementation is tested on a molecular dynamics simulation of spinodal phase separation.
New Insights into the Crystallization Process of Calcium Carbonate by a Contact-Free in situ Scattering Technique using a Levitating Drop Method
2008
Surface effects on spinodal decomposition in binary mixtures and the interplay with wetting phenomena.
1994
The phase separation of binary mixtures in a semi-infinite geometry is investigated both by a phenomenological theory and by numerical calculations using a discrete equivalent of the descriptive equations. In the framework of ``model B'' (which describes solid binary mixtures), attention is paid to a proper treatment of the boundary conditions at the free surfaces. We confine ourselves to short-range surface forces and consider parameter values that correspond to both nonwet and wet surfaces in thermal equilibrium. During the initial stages of spinodal decomposition, after a quench from considering an initial condition that corresponds to a completely random concentration distribution, one …
Ab initio thermodynamics for the growth of ultra-thin Cu film on a perfect MgO(001) surface
2005
Controlled growth of thin metallic films on oxide substrates is important for numerous micro-and nanoelectronic applications. Our ab initio study is devoted to the periodic slab simulations for a series of ordered 2D Cu superlattices on the regular MgO(001) substrate. Submonolayer and monolayer substrate Cu coverages were calculated using the DFT-GGA method, as implemented into the CRYSTAL-98 code. The results of ab initio calculations have been combined with thermodynamic theory which allows us to predict the growth mode of ultra-thin metal films (spinodal decomposition vs. nucleation-and-growth regime) as a function of the metal coverage and the temperature, and to estimate the metal dens…
Phase separation of binary mixtures in thin films: Effects of an initial concentration gradient across the film.
2012
We study the kinetics of phase separation of a binary (A,B) mixture confined in a thin film of thickness $D$ by numerical simulations of the corresponding Cahn-Hilliard-Cook (CHC) model. The initial state consisted of 50$%$ A:50$%$ B with a concentration gradient across the film, i.e., the average order parameter profile is ${\ensuremath{\Psi}}_{\mathrm{av}}(z,t=0)=(2z/D\ensuremath{-}1){\ensuremath{\Psi}}_{g},\phantom{\rule{0.28em}{0ex}}0\ensuremath{\leqslant}z\ensuremath{\leqslant}D$, for various choices of ${\ensuremath{\Psi}}_{g}$ and $D$. The equilibrium state (for time $t\ensuremath{\rightarrow}\ensuremath{\infty}$) consists of coexisting A-rich and B-rich domains separated by interfac…
Dynamics of crystallization in hard-sphere suspensions.
1996
Density fluctuations are monitored by small-angle light scattering during the crystallization of 0.22-\ensuremath{\mu}m-radius, hard colloidal spheres. Measured structure factors show an intensity maximum at finite-scattering vectors. The shape of the intensity distribution scales at early times during nucleation and growth and again at large times during ripening. At intermediate times there is a crossover region where scaling ceases to be valid. Both the amplitude and the position of the maximum intensity show quasi-power law behavior in time. The values of the observed exponents are within the range expected for classical growth models. The breadth of the intensity distribution increases…
Spinodal Decomposition in Binary Polymer Blends: Monte Carlo Simulations and Dynamic Mean Field Theory
2001
Using large scale computer simulations we have investigated the interplay between single chain dynamics and the kinetics of phase separation in a symmetric binary polymer blend. In the framework of a coarse grained lattice model — the bond fluctuation model on a three dimensional lattice — we monitor the growth of concentration fluctuations after a quench from the one phase region into the miscibility gap. Chains of 64 effective segments are simulated in a cell of linear dimension L = 160, i.e., each simulation box contains 256 000 particles. The growth rate of composition fluctuations is averaged over 64 realizations of the temperature quench.