Molecular-dynamics simulation of directional growth of binary mixtures (original) (raw)
Related papers
Molecular Dynamic Simulation of Directional Crystal Growth
Springer Proceedings in Physics, 2000
We use molecular dynamic to simulate the directional growth of binary mixtures. our results compare very well with analitical and experimental results. This opens up the possibility to probe growth situations which are difficult to reach experimentally, being an important tool for further experimental and theoretical developments in the area of crystal growth.
Molecular dynamics methodology to investigate steady-state heterogeneous crystal growth
Chemical Physics, 2007
In this paper a new molecular dynamics simulation methodology to investigate steady-state heterogeneous crystal growth from a supercooled liquid is presented. The method is tested on pure component systems such as Lennard-Jonesium and water/ice, as well as multicomponent systems such as methane hydrate crystals. The setup uses periodicity in all three directions and two interfaces; at one interface, crystallization occurs, while at the other, melting is enforced by locally heating the crystal only near that interface. Steady-state conditions are achieved when the crystal is melted at the same rate as the growth occurs. A self-adaptive scheme that automatically modifies the rate of melting to match the rate of growth, crucial for establishing steady-state conditions, is described. In contrast with the recently developed method of Razul et al. ͓Mol. Phys. 103, 1929 ͑2005͔͒, where the rates of growth ͑melting͒ were constant and the temperatures determined, the present approach fixes the supercooling temperature at the growing interface and identifies the corresponding steady-state crystal growth rate that corresponds to the thermodynamic force provided. The static properties of the interface ͑e.g., the interfacial widths͒ and the kinetics of the crystal growth are found to reproduce well previous findings. The importance of establishing steady-state conditions in such investigations is also briefly discussed.
Towards an atomic-scale understanding of crystal growth in solution
Faraday Discussions, 2007
Our understanding of crystal growth continues to increase thanks to progress in theoretical models, computer simulations and experimental techniques. A discussion of the state-of-the-art in morphology prediction and of the determination of the solid-liquid interface structure using X-ray diffraction shows, however, that there is still a large gap between experiment and theory. We expect that computer modelling, in the form of both Molecular Dynamics simulations and first-principle calculations, will play a crucial role in filling this gap.
Computer simulations of heterogeneous crystal growth of atomic systems
Molecular Physics, 2005
The systematic study of the mechanisms of heterogeneous crystal growth has proven somewhat difficult. Here we briefly review previous work in this area. We then report a novel molecular dynamics simulation methodology that has been developed to enable the creation of steady-state crystal growth-melting. We employ this methodology to examine BCC and FCC 001, 011 and 111 crystal faces of systems of spherical particles interacting through Lennard-Jones and inverse sixth-power potentials. Various growth-melting conditions are explored involving different temperature gradients and velocities. Profile functions of various quantities across the interface have been recorded; as measured in the moving frame by the present approach, these functions are effectively averaged over the molecular detail of the interface and become smooth. This characteristic allows for new ways of interpreting profile functions like the energy and local structural order parameters. We find that when the derivative of these profile functions is taken with respect to the z dimension, we obtain consistent peaks that characterize the freezing-melting interfaces. Consequently, the position and width of an interface are easily identified. The interfacial widths calculated show that it is somewhat dependent on the temperature gradient but no dependence on the growth velocity was observed. The interfacial widths are found to decrease in the order 001 >011 > 111. Furthermore we determine interfacial tensions, which arise directly out of our methodology. We are able to demonstrate that ordering and disordering are distinct and different processes occurring at both the melting and freezing interfaces.
Monte Carlo studies of equilibrium and growth shapes of a crystal
Physical review, 1989
The equilibrium and growth morphology of a crystal in a diffusion field are studied by means of a lattice-gas model in a unified way. In a closed system the crystal takes an equilibrium form, and its shape and size in two dimensions agree with those expected from the exact solutions of the corresponding Ising model. In an open system where a crystal is in contact with a gas reservoir, the crystal grows steadily. For a small crystal or at a small chemical potential difference Ap between the gas and the crystal, the growth form is polygonal. Its growth rate and the size are interpreted by a single nucleation and growth mechanism. On increasing Ap or for a large crystal, it becomes dendritic. Further increase of Ap results in a fractal aggregate, which is, however, "compact" in a large scale due to the finiteness of the gas density.
2021
The evolving domain structures in phase separating mixtures can significantly influence the final properties of materials. We present here the effect of quenched disorder (in the form of bond-disorder) on the kinetics of phase separating binary (AB) mixtures. Our particular focus is on the domain structure, phase behavior, growth laws, and dynamical scaling. The bond disorder (BD), which acts as an impurity in the system, is introduced in a regular manner. To model the evolution kinetics, we utilize the well-known conserved spin-exchange (Kawasaki) kinetics on a two-dimensional (2d) Ising system via an extensive Monte Carlo (MC) simulation study. The effect of BD is analyzed for the critical (AB) mixtures. We observed that the dynamical scaling, exhibited by the scaled correlation function and the corresponding structure factor, changes by varying the number of disordered sites at different temperatures below the critical temperature (Tc). When the system is deeply quenched at the l...
Journal of Computational Physics, 2005
A phase-field model for non-isothermal solidification in multicomponent systems [SIAM J. Appl. Math. 64 (3) (2004) 775-799] consistent with the formalism of classic irreversible thermodynamics is used for numerical simulations of crystal growth in a pure material. The relation of this approach to the phase-field model by Bragard et al. [Interface Science 10 (2-3) (2002) 121-136] is discussed. 2D and 3D simulations of dendritic structures are compared with the analytical predictions of the Brener theory [
Crystal growth mechanisms: Interface kinetics
Materials Chemistry, 1979
A survey is given of the main theories on the interfacial kinetics of the growth from vapour and solution. Apart from the classical theory of the growth of singular faces by the 2D nucleation mechanism (mononuclear and polynuclear), special stress is laid on the fundamental of the theory of Burton, Cabrera and Frank for both the surface and volume diffusion; its more significant developments are considered as well (Chernov model on the volume diffusion, Gilmer, Ghez and Cabrera analysis of combined surface and volume diffusion processes). Furthermore the analysis of the implications of the Miiller-Krumbhaar generalized equation for crystal growth is carried out, when applied to the growth of spirals under an anisotropic chemical potential
Kinetics of rapid crystal growth: phase field theory versus atomistic simulations
IOP Conference Series: Materials Science and Engineering, 2019
Kinetics of crystal growth in undercooled melts is analyzed by methods of theoretical modeling. Special attention is paid to rapid growth regimes occurring at deep undercoolings at which non-linearity in crystal velocity appears. A traveling wave solution of the phase field model (PFM) derived from the fast transitions theory is used for a quantitative description of the crystal growth kinetics. The “velocity – undercooling” relationship predicted by the traveling wave solution is compared with the data of molecular dynamics simulation (MDS) which were obtained for the crystal-liquid interfaces growing in the 〈 100〉-direction in the Ni50Al50 alloy melt.