A concise and general formula is introduced to obtain ab initio pair
potentials between atoms across a metal–ceramic interface by inversion of
the adhesive energies of the interface. Derivation of interfacial potentials
ΦAg−Mg
and ΦAg−O
from ab initio adhesive energies is performed by applying the formula to the Ag/MgO(001)
interface. Transferability of these potentials at Ag/MgO(100), Ag/MgO(110) and
Ag/MgO(111) interfaces is discussed.
This paper investigates the properties of dislocations in Pd/MgO(001)
interfaces. By constructing ideal and virtual interface structures and applying
the Chen–Mobius inversion method, we obtain interatomic potentials
ΦPd–Mg
and ΦPd–O
directly from ab initio adhesive energies. Then, by applying the above potentials, as well as
using the atomistic relaxation and molecular dynamics methods, stable interface structures
are obtained. For simplicity, we use a two-dimensional model to provide some clear physical
pictures of the dislocations. There are two kinds of mechanisms of dislocation formation:
one is insertion of an extra slice of Pd atoms; the other is increasing the number of Pd
layers, to produce dislocations via the increasing misfit stress. Finally, three-dimensional
models are investigated, with dislocations perpendicularly intersecting in the
interface. The calculated interfacial distances are in agreement with experiments.
Misfit dislocation is an important component of the semi-coherent interface.
Usually, it forms a dislocation network as the strain concentration area
on an interface and makes the other part coherent. This is the regular
case, but there are also some exceptions. In this work, we show that the
Ni/(Al2O3)Al
interface has a reconstruction at the first monolayer of the
metal side, which works as a transition layer between Ni and
Al2O3
lattices. Under these conditions, the misfit dislocation cannot be confirmed by drawing a
Burgers circuit because the interface is incoherent. However, due to the lattice misfit, there
are areas of strain concentration and areas without strain distributed on the interface
plane. So, for describing this strain distribution, we again use the concept of a dislocation
network but redefine it as the separate line between these two parts. As a result, we find
that the dislocation network appears when the metal part is thicker than 12.4 Å, and it
shrinks as the metal film grows, resulting in an ultimate structure with a mesh size of 28.1 Å.
The atomistic simulation of a metal/oxide interface is a challenge in surface science and
technology. It requires a systematic way of obtaining the interatomic potentials across
the interface. In this work, we use a Chen–Möbius inversion method to study the
Ni/Al2O3
interface, and get a concise and general inversion formula, which is used to extract pair
potentials from ab initio adhesive energies. A series of checks show that the inversed
potentials are self-consistent and also partially transferable. These potentials prefer to treat
the Al terminated interface, but are not so good for the O terminated interface. In
summary, the present work provides a novel way to get the ab initio based pair potentials
across an interface, with the derivation of an inversion formula of both theoretical and
practical importance.
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