Reaction pathways in atomistic models of thin film growth

Lloyd, Adam L.; Zhou, Ying; Yu, Miao; Scott, Chris; Smith, Roger; Kenny, Steven D.

doi:10.1063/1.4986402

Cited by 10 publications

(9 citation statements)

References 44 publications

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“…Chemical reactions between liquid phase species and a solid surface are the precursors to growth of solid or semisolid films in a variety of applications. Understanding the pathways for these reactions is therefore an important step towards optimization of film growth parameters [1,2]. Here, we focus on reactions between tri-cresyl phosphate (TCP) and an amorphous iron oxide surface.…”

Section: Introductionmentioning

confidence: 99%

Synergistic effect of nanodiamonds on the adsorption of tricresyl phosphate on iron oxide surfaces

Khajeh

Krim

Martini

2019

Applied Physics Letters

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Nanodiamonds (NDs) have potential uses in many applications, including as additives for liquid lubricants, where they may be combined with more traditional chemicals to form protective films on sliding surfaces. It has been shown that NDs can function synergystically with tri-cresyl phosphate (TCP) to facilitate film formation on air baked iron. Here, reactive molecular dynamics simulations of TCP and NDs on an amorphous iron oxide surface reproduce experimental observations of the temperature at which film formation begins with NDs present and the effect of NDs on film composition. Analysis of chemical bonding in the simulations shows that the film formed in the presence of NDs is comprised of NDs and TCP that are both directly and indirectly bonded to the surface. Notably, the amount of phosphorous in the film, which is important for surface protection, is increased by TCP molecules that are indirectly bonded to the surface via NDs, which suggests that indirect bonding is one mechanism by which NDs facilitate film growth. The synergy of NDs and TCP has important implications for the development of NDs as emerging lubricant additives which must function with existing additives such as TCP in many applications.

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Section: Introductionmentioning

confidence: 99%

Synergistic effect of nanodiamonds on the adsorption of tricresyl phosphate on iron oxide surfaces

Khajeh

Krim

Martini

2019

Applied Physics Letters

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“…Super-basins are built on-the-fly by exploring all states connected by lowbarrier transitions and then removing these transitions from the KMC event table allowing only the escaping transitions to be included -hence accelerating the simulation time. The super-basin method implemented in our code is an extension of the on-lattice method described in [2] and the off-lattice method further described in [29] where local basins are built from defect volumes, rather than including the whole system. This allows multiple basins to exist simultaneously.…”

Section: Super Basin Methodsmentioning

confidence: 99%

“…To save computation time, a subsystem is created when making open ended saddle point searches which surrounds system defects and adatoms; typically a radius of >4NN is used. The methodology is described in more detail in [29] but typically defect volumes are created around atoms that differ in co-ordination number from those that would occur in a perfect crystal bulk or surface. If multiple defects exist within a defined distance (double the defect volume radius) from each other, the subsystems are combined to create a larger defect volume.…”

Section: Defect Volumesmentioning

confidence: 99%

Modelling thin film growth in the Ag–Ti system

et al. 2019

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Simulations of thin film growth in the Ag-Ti system are presented using molecular dynamics combined with an adaptive kinetic Monte Carlo method (AKMC) with a modified embedded atom potential fit to ab initio data for the surface energies. For the model, atoms are assumed to deposit normally with a kinetic energy of 1-3 eV, with a typical deposition rate of around 10 monolayers per second, similar to what might be expected in a sputter deposition process. For the growth of Ti on the Ag (100) and Ag (111) surfaces, the Ti adatoms prefer to exchange with the original surface layer atoms creating a mixed Ag/Ti surface. On a silver substrate, up to four mixed layers need to be formed before a pure Ti layer is obtained. Conversely, simulations of Ag depositing onto Ti (0001) showed that in the initial phase of growth, the Ag adatoms prefer to be separated before a complete first layer of Ag was obtained in a close-packed structure. The implementation of a super-basin method within AKMC allowed the simulation of 0.4s of Ti growth on the Ag substrates, with up to 3 new layers added.

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“…The AKMC approach has been used to identify many complex transition pathways and mechanisms for thin film growth. 17 Initially a substrate of dimension 2.28 Â 0.81 Â 2.63 nm (with periodic boundary conditions in the x and z directions, parallel to the surface) was used which consisted of 4 double layers with 64 O and 64 Zn atoms in each layer. Despite a small system being simulated, the substrate's dimensions in the periodic directions are much larger than the 1 nm cut-off distance applied to the bond order potential function.…”

Section: A Akmcmentioning

confidence: 99%

Growth of silver on zinc oxide via lattice and off-lattice adaptive kinetic Monte Carlo

2018

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The growth of Ag on ZnO was modeled using a reactive force field potential and a combination of molecular dynamics and adaptive kinetic Monte Carlo (AKMC) simulations. An adaptive lattice-based AKMC model is described as a method of extending timescales and length scales that can be simulated. Reusing previously found transitions to reduce computational time is discussed for both the lattice and off-lattice AKMC approaches. With these methods, growth of over 1 monolayer's worth of Ag is simulated corresponding to a real deposition time of up to 0.1 s. The results show that the deposited silver aggregates on the surface through mainly single atom moves with few concerted motions. Initially silver adatoms do not agglomerate and the energy barriers for silver dimers to form are larger than for them to break apart. The first layer of silver grows as a series of connected regions rather than forming well-defined centro-symmetric islands.

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Reaction pathways in atomistic models of thin film growth

Cited by 10 publications

References 44 publications

Synergistic effect of nanodiamonds on the adsorption of tricresyl phosphate on iron oxide surfaces

Synergistic effect of nanodiamonds on the adsorption of tricresyl phosphate on iron oxide surfaces

Modelling thin film growth in the Ag–Ti system

Growth of silver on zinc oxide via lattice and off-lattice adaptive kinetic Monte Carlo

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