טכניון מכון טכנולוגי לישראל
הטכניון מכון טכנולוגי לישראל - בית הספר ללימודי מוסמכים  
Ph.D Thesis
Ph.D StudentAdham Hashibon
SubjectAtomistic Study of Structural Correlations at a Model
Solid/Liquid-Metal Interface
DepartmentDepartment of Physics
Supervisors Dr. Adler Joan
Professor Emeritus Lipson Stephen
Full Professor Kaplan Wayne D.


Abstract

Despite its relevance to technology, the understanding of the structure at solid-liquid interfaces is still incomplete.  In this study a model system for a solid-liquid metal heterophase interface is introduced.  The solid is assumed to be composed of static atoms positioned in an ideal lattice with a fixed symmetry, and the liquid is introduced adjacent to several different terminating planes of the solid. The molecular dynamics technique is applied to study structural correlations between the liquid metal and the solid on systems of up to 4500 atoms.  The density profile and the ordering within the liquid were investigated for different substrate crystallographic orientations and temperatures.  The density profile showed periodic oscillations, in which the magnitude of the oscillations dampens exponentially with distance from the solid. The decay constant k, of the density oscillations defines a quantitative measure of disorder across the interface. A strong correlation between the amount of ordering, as given by the inverse of k, in the liquid phase and the underlying substrate orientation was found. It was also found that k depends on the strength of the solid-liquid interaction. It was also concluded that the ordering of the liquid at the interface is governed by both the structure of the solid substrate, and the properties of the liquid metal. If good wetting exists between the solid and the liquid materials, the liquid will form layers adjacent to the interface. If, in addition, the structure of the solid and the structure of the metal upon freezing are compatible, substantial in-plane ordering within the liquid layers occurs, whereas in the case of incompatible materials the layers will be liquid like.