Analysis of Oxygen Segregation at Metal-Oxide Interfaces Using a New Lattice Monte Carlo Method

2007 ◽  
Vol 129 ◽  
pp. 111-117 ◽  
Author(s):  
Irina V. Belova ◽  
Graeme E. Murch ◽  
Nilindu Muthubandara ◽  
Andreas Öchsner
Keyword(s):  
Monte Carlo ◽  
Monte Carlo Method ◽  
Physical Properties ◽  
Atomic Oxygen ◽  
Oxide Interfaces ◽  
Bulk Properties ◽  
Ceramic Oxide ◽  
Lattice Monte Carlo ◽  
Metal Ceramic ◽  
Constant Source

The presence of atomic oxygen at internal metal-ceramic oxide interfaces significantly affects the physical properties of the interfaces which in turn affects the bulk properties of the material. We address this problem for the case of a constant source of oxygen at the surface and periodic arrangements of ceramic oxide (MgO) inclusions embedded in a metal (Ag) matrix. We simulate the time-dependence of the oxygen concentration into the material using a newly developed lattice Monte Carlo method that takes into account a constant source of diffusant.

On some Conceptual Considerations for the Finite Element Simulation of the Oxygen Out-Diffusion in Ag-MgO Composites

2009 ◽  
Vol 283-286 ◽  
pp. 1-5
Author(s):  
Andreas Öchsner
Keyword(s):  
Finite Element ◽  
Physical Properties ◽  
Atomic Oxygen ◽  
Oxide Interfaces ◽  
Bulk Properties ◽  
Nite Element ◽  
Element Simulation ◽  
Metal Ceramic ◽  
Numerical Tools ◽  
The Right

The presence of atomic oxygen at internal metal-ceramic oxide interfaces signi¯- cantly affects the physical properties of the interfaces which in turn affects the bulk properties of the material. The application of numerical tools such as the ¯nite element method requires some conceptional considerations if results from different finite element meshes of methods should be comparable. This paper summarises some of these thoughts in order to provide the right basis for comparative investigations.

scholarly journals Finite Element Modelling of Oxygen Diffusion and Segregation at Interfaces in Ag-MgO Composites: Parametric Studies

2008 ◽  
Vol 273-276 ◽  
pp. 461-466
Author(s):  
Andreas Öchsner ◽  
Irina V. Belova ◽  
Graeme E. Murch
Keyword(s):  
Finite Element ◽  
Finite Element Modelling ◽  
Atomic Oxygen ◽  
Model System ◽  
Point Of View ◽  
The Finite Element Method ◽  
Oxide Interfaces ◽  
Bulk Properties ◽  
Metal Ceramic ◽  
Parametric Studies

The presence of atomic oxygen at internal metal-ceramic oxide interfaces signifi- cantly affects the physical properties of the interfaces which in turn affects the bulk properties of the material. This problem is addressed for the model system Ag-MgO from a phenomenolog- ical point of view using the finite element method. The performed parametric studies investigate the influence of different kinetic parameters of the diffusion-segregation system.

scholarly journals Modelling of Oxygen Diffusion and Segregation at Interfaces in Ag-MgO Composites

2007 ◽  
Vol 266 ◽  
pp. 29-38
Author(s):  
Irina V. Belova ◽  
Andreas Öchsner ◽  
Nilindu Muthubandara ◽  
Graeme E. Murch
Keyword(s):  
Oxygen Diffusion ◽  
Atomic Oxygen ◽  
Composite System ◽  
Point Of View ◽  
Model Composite ◽  
Oxide Interfaces ◽  
Bulk Properties ◽  
Metal Ceramic ◽  
Phenomenological Point ◽  
Good Agreement

The presence of atomic oxygen at internal metal-ceramic oxide interfaces significantly affects the physical properties of the interfaces which in turn affects the bulk properties of the material. This problem is addressed for the model composite system Ag-MgO from a phenomenological point of view using a lattice-based Monte Carlo method and a finite element method extended with special user-subroutines. We simulate the time dependence of oxygen depth and contour profiles. We are able to show very good agreement between these two methods.

scholarly journals Calculations of the Effective Thermal Conductivity in a Model of Syntactic Metallic Hollow Sphere Structures Using a Lattice Monte Carlo Method

2008 ◽  
Vol 273-276 ◽  
pp. 216-221 ◽  
Author(s):  
Thomas Fiedler ◽  
Andreas Öchsner ◽  
Irina V. Belova ◽  
Graeme E. Murch
Keyword(s):  
Thermal Conductivity ◽  
Monte Carlo ◽  
Monte Carlo Method ◽  
Effective Thermal Conductivity ◽  
Hollow Sphere ◽  
Cutting Planes ◽  
Two Dimensional ◽  
Adhesively Bonded ◽  
Lattice Monte Carlo ◽  
The Matrix

In this paper, a Lattice Monte Carlo method is used to determine the effective thermal conductivity in two dimensional models of adhesively bonded metallic hollow sphere structures (MHSS). In contrast to earlier approaches, more realistic distributions of spheres without the simplification of cubic symmetric arrangements are considered in this study. For the Monte Carlo analyses, two-dimensional periodic lattices representing different cutting planes through MHSS are generated. Therefore, an algorithm is used which sequentially fills the lattice by adding cut spherical shells and inclusions in the matrix. Another focus of this work is the analysis of the influence of different geometric circle distributions on the effective thermal conductivity. The findings of the random arrangements are also compared to a regular primitive cubic arrangement and with a Maxwell-type approach.

scholarly journals Impurity lattice Monte Carlo for hypernuclei

2020 ◽  
Vol 56 (10) ◽  
Author(s):  
Dillon Frame ◽  
Timo A. Lähde ◽  
Dean Lee ◽  
Ulf-G. Meißner
Keyword(s):  
Field Theory ◽  
Monte Carlo ◽  
Monte Carlo Method ◽  
Effective Field Theory ◽  
Computational Effort ◽  
Effective Field ◽  
Binding Energies ◽  
Chiral Effective Field Theory ◽  
Lattice Monte Carlo ◽  
Nucleon Interactions

AbstractWe consider the problem of including $$\varLambda $$ Λ hyperons into the ab initio framework of nuclear lattice effective field theory. In order to avoid large sign oscillations in Monte Carlo simulations, we make use of the fact that the number of hyperons is typically small compared to the number of nucleons in the hypernuclei of interest. This allows us to use the impurity lattice Monte Carlo method, where the minority species of fermions in the full nuclear Hamiltonian is integrated out and treated as a worldline in Euclidean projection time. The majority fermions (nucleons) are treated as explicit degrees of freedom, with their mutual interactions described by auxiliary fields. This is the first application of the impurity lattice Monte Carlo method to systems where the majority particles are interacting. Here, we show how the impurity Monte Carlo method can be applied to compute the binding energies of the light hypernuclei. In this exploratory work we use spin-independent nucleon–nucleon and hyperon–nucleon interactions to test the computational power of the method. We find that the computational effort scales approximately linearly in the number of nucleons. The results are very promising for future studies of larger hypernuclear systems using chiral effective field theory and realistic hyperon–nucleon interactions, as well as applications to other quantum many-body systems.

Lattice Monte Carlo Simulations of Vacancy-Mediated Diffusion and Aggregation using Ab-Initio Parameters

1997 ◽  
Vol 469 ◽  
Author(s):  
Marius M. Bunea ◽  
Scott T. Dunham
Keyword(s):  
Monte Carlo ◽  
Monte Carlo Method ◽  
Nearest Neighbor ◽  
First Principle ◽  
High Concentration ◽  
Lattice Monte Carlo ◽  
First Principle Calculations ◽  
System Energy ◽  
Concentration Diffusion ◽  
Nearest Neighbor Distances

The lattice Monte Carlo method with parameters from recent first-principle calculations1,2 are used to investigate dopant diffusion in silicon. In the simulations, vacancy hopping on a silicon lattice is biased by changes in system energy, including interactions up to the sixth-nearest neighbor. We find that vacancy-mediated diffusivity increases dramatically above 1020 cm−3, in agreement with experimental observations3 and previous calculations.4 However, for very long simulation times, arsenic diffusivity is reduced due to formation of AsxV complexes, with clustering more pronounced at high doping levels. As suggested by Ramamoorthy and Pantelides,5 we find that As2V complexes are mobile, and although they diffuse much more slowly than AsV pairs, they appear likely to have a significant role in high concentration diffusion due to their much higher numbers. We also investigated dopant fluxes in a vacancy gradient. For dopants like As for which pair diffusion is limited by the dissociation to third-nearest neighbor distances, the dopant flux is less than that predicted by pair diffusion models, with greater difference at higher temperatures. In contrast, for phosphorus/vacancy pairs, whose diffusion is limited by dopant/vacancy exchange, the dopant flux is close to the predictions of pair diffusion.

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