Wyniki wyszukiwania - BazTech

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Surface diffusion and cluster formation of gold on the silicon (111)

Plechystyy V., Shtablavyi I., Rybacki K., Winczewski S., Mudry S., Rybicki J.

Journal of Achievements in Materials and Manufacturing Engineering

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2020

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Vol. 101, nr 2

49--59

EN

Purpose: Investigation of the gold atoms behaviour on the surface of silicon by molecular dynamics simulation method. The studies were performed for the case of one, two and four atoms, as well as incomplete and complete filling of gold atoms on the silicon surface. Design/methodology/approach: Investigations were performed by the method of molecular dynamics simulation using the Large-scale Atomic/Molecular Massively Parallel Simulator (LAMMPS). MEAM potential of interatomic interaction was used for modelling. Molecular dynamic simulations were carried out in isothermal-isobaric ensemble (NpT) with a timestep 1.0 fs. Findings: As a result of studies, the preferred interaction between gold atoms and the formation of clusters at temperatures up to 800 K was revealed. Analysis of the temperature dependences of the number of large jumps of atoms made it possible to calculate the activation energy of a single jump. It was found that activation energy of single atomic displacement decreases with increasing number of gold atoms. Research limitations/implications: Only a limited number of sets of atoms were used in the study. It is possible that for another combination of atoms and a larger substrate surface, the formation of gold nanoislands on the silicon surface can be observed, which requires further research. Practical implications: The research results can be used to select the modes of gold sputtering to create gold nanoislands or nanopillars on the silicon surface. Originality/value: Computer modelling of the behaviour of gold atoms on the surface of silicon with the possibility of their self-organization and cluster formation was performed for the first time.

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Improvements to the two-phase sandwich method for calculating the melting points of pure metals

Rybacki K., Winczewski S., Pleechystyy V., Rybicki J.

Computational Methods in Science and Technology

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2019

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Vol. 25, No. 2

105--116

EN

The thermophysical properties of metal alloys are often investigated via molecular dynamics (MD) simulations. An exact and reliable estimation of the thermophysical parameters from the MD data requires a properly and carefully elaborated methodology. In this paper, an improved two-phase sandwich method for the determination of the metal melting temperature is proposed, based on the solid-liquid equilibrium theory. The new method was successfully implemented using the LAMMPS software and the C++11 Standard Libraries and then applied to aluminum and copper systems. The results show that the proposed procedure allows more precise calculations of the melting temperature than the widely used onephase boundary methods.

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Structure and thermal expansion of liquid bismuth

Mudry S., Shtablavyi I., Liudkevych U., Winczewski S.

Materials Science Poland

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2015

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Vol. 33, No. 4

767--773

EN

Experimental structural data for liquid Bi were used for estimation of the main structure parameters as well as the thermal expansion coefficient both in super cooled and superheated temperature ranges. It was shown that the equilibrium melt had a positive thermal expansion coefficient within a temperature range upon melting and a negative one at higher temperatures. The former was related to structure changes upon melting, whereas the latter with topologic disordering upon further heating. It was found that the superheated melt had a negative thermal expansion coefficient. The results obtained from structural data were compared with the thermal expansion coefficient calculated from the data of density for liquid Bi.

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Structure of Small Platinum Clusters Revised

Winczewski S., Rybicki J.

Computational Methods in Science and Technology

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2011

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Vol. 17, No. 1-2

75-85

EN

Systematic studies on the structure of platinum clusters consisting of N = 2-15 atoms were performed using density functional theory. The results show that up to N = 9 atoms planar structures are as stable as three- dimensional ones. For larger clusters, both distorted and disordered spatial structures are preferred. The global minima of N = 10- and 14-atom clusters were found to possess fcc-like structures with significantly higher stability.