Study of the thermodynamic characteristics of gold nanoclusters using a Gupta many-body potential

The Monte Carlo method has been employed to investigate the hysteresis of the process of melting and crystallization of gold nanoclusters using a many-body Gupta potential. The size dependence of the effective specific total surface energy of gold nanoclusters has been calculated and analyzed based on the Gibbs surface phase method.     

Molecular dynamics simulation of the formation of bimetallic core-shell nanostructures with binary Ni–Al nanoparticle quenching

Journal of Materials Science - Employing isothermal molecular dynamics, we simulated the self-assembly of core-shell nanostructures in the course of quenching binary Ni–Al nanoparticles (NPs)...     

A long-range influence of the argon-ion irradiation on the silicon nitride layers formed by the ion implantation

The effect of stimulating synthesis reactions for the Si₃N₄ phase in nitrogen-enriched silicon layers under the influence of argon-ion implantation into the rear side of silicon wafers was investigated. Dependences of variations in the IR absorption and the resistivity of the synthesized layers on argon-implantation dose were obtained. The morphology of a wafer surface after argon implantation with various doses was investigated by atomic-force microscopy. The effect is attributed to the action of shock waves arising owing to microbursts of argon blisters.     

Gupta multiparticle potential study of the hysteresis of the melting and solidification of gold nanoclusters

The processes of melting and solidification of gold nanoclusters consisting of 43, 55, 87, 177, 249, 381, 767, and 1055 atoms are studied using the Monte Carlo method and the Gupta multiparticle potential. It is shown that the temperature dependences of the potential part of the specific internal energy of gold nanoclusters and the average first coordination number have pronounced hystereses. The size dependences of the melting and solidification temperatures are found. Based on an analysis of the temperature dependence of the potential part of the specific internal energy of gold nanoclusters, the temperature dependence of the specific specific heat of a cluster consisting of 1055 atoms during melting and solidification has been found. The size dependence of the specific heat of nanoparticles is analyzed.     

Fractal Dimension Behaviour of Maze Domain Pattern in Ferrite-Garnet Films During Magnetisation Reversal

Journal of Superconductivity and Novel Magnetism - Experimental results of the study of magnetic bismuth-containing ferrite-garnet films grown on substrates from gadolinium-gallium garnet are...     

Electron spin resonance and photoluminescence in pyrolytic silicon nitride films irradiated with argon and molecular ions

The photoluminescence and electron spin resonance phenomena are studied at room temperature for pyrolytic silicon nitride films irradiated with argon ions or molecular nitrogen ions and annealed at temperatures in the range 500–1100°C. The absorption spectrum suggests that the broad photoluminescence band at 400–600 nm is due to electron transitions between the band tails. The low-dose irradiation with argon ions slightly reduces the photoluminescence intensity, whereas the high-dose irradiation followed by annealing at 800–900°C can induce a more than twofold increase in the intensity. At the same time, irradiation with nitrogen ions profoundly suppresses the integrated photoluminescence intensity that decreases by more than an order of magnitude. A correlation between the changes in the photoluminescence intensity and the amplitude of the ESR spectra on annealing of the silicon nitride films is observed.     

Relation between the size dependences of the melting and crystallization temperatures of metallic nanoparticles

The relation between the melting and crystallization temperatures of metallic nanoparticles is studied using a thermodynamic approach. The size dependences of the melting temperatures of tin and copper nanoparticles are calculated with allowance for the corresponding size dependences of the surface tensions of the solid and liquid phases and the interfacial tension. The size dependences of the crystallization temperature are obtained with allowance for the effective surface layer (skin layer) that forms in melting of a nanoparticle.     

Variations in the properties of an implantation-synthesized SixNy-Si heterosystem as a result of thermal and ion-beam treatments

Transmission electron microscopy, infrared spectroscopy, and the measurements of current-voltage characteristics and capacitance were used to study the influence of heat treatment and the long-range effect of irradiation of the rear side of an Si wafer with Ar, Ne, and Si ions on the state of an Si_xN_y layer synthesized at the front side of this wafer. It is ascertained that the argon-ion bombardment of the wafer heated to 500°C is the most effective method for the formation of insulating silicon-nitride layers. The fact that the properties of Si_xN_y layers are scarcely affected by irradiation with neon and silicon ions is consistent with the previously suggested model of a spontaneous-acoustic mechanism of the long-range effect produced by irradiation of silicon with argon ions.