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Gamma‐ray, fast neutron and charged particle shielding characteristics of Praseodymium (Pr3+) activated glasses with composition 10ZnF2‐(10‐x)SrO‐15Li2O‐65H3BO3‐xPr2O3(where x = 0.1, 0.5, 1.0, 1.5, and 2.0) are investigated. For this, the radiation shielding parameters are estimated by using Photon Shielding and Dosimetry (Phy‐X/PSD), Interaction of Proton, Alpha, Gamma rays, Electrons, and X‐rays with matter (PAGEX), Stopping Powers and Ranges for Electrons (ESTAR), and The Stopping and Range of Ions in Matter (SRIM) codes. Furthermore, the results are compared comprehensively and comparatively. The glasses with increasing Pr3+ content exhibited higher shielding potential. It can be said that the ZFLHBPr2.0 sample could be used as a shielding material in various applied fields. Additionally, the effect of Pr composition on structural transitions and time‐dependent volume‐collapse of this new family of borate glass doped with Pr is analyzed by molecular dynamics study (MD) based density functional tight binding method. The simulation results show that the addition of Pr led to the cubic‐orthorhombic transformation of simulation cell at determined temperature and 1 atm pressure. Also, a sudden decrease in volume are observed within a short time at 8% Pr composition (x = 2.0) atmospheric pressure. This result provides a strong connection between Pr composition and volume change with time and at constant low pressure. [ABSTRACT FROM AUTHOR]

In the presented study, Fe-Cr-Ni ternary alloy system, which is classified as medium entropy alloys, was modelled using molecular dynamics (MD) simulation method. Model system was built at specific concentration ratios in accordance with the crystal lattice structures in the phase diagrams. The potential energy function based on the Grujicic-Zhou (GZ) type embedded atom method (EAM) was chosen as the potential function suitable for the system. The phase transformation mechanisms of the model system were investigated by applying heating-cooling processes on the most stable structures. In these processes, thermodynamic parameters such as temperature, volume, potential energy and density were calculated. In addition, the phase transformation mechanism and structural properties were analysed using radial distribution functions (RDF). Three-dimensional pictures of MD cells and the number of crystal structures were obtained using the visualization and analysis software via the atomic positions obtained during the transformations. In all these processes, the results obtained by the MD calculation method were interpreted and compared with the experimental data. [ABSTRACT FROM AUTHOR]

In this study, the local order and the structural evolution of the PdAg binary alloy system during the crystallization process from the amorphous phase under different pressures was investigated using the molecular dynamics simulation method. The structural development and phase transformation of the model alloy system for pressures of 0,1, and 5 GPa are analysed based on variations of the radial distribution function, the bond orientational order parameters, and Honeycutt-Andersen bond-type index method. The simulation results showed that higher pressures favoured amorphous-type atomic clusters and had an important effect on the bond orientational order parameters of the model system of the transformation from amorphous state to stable crystal phase during the isothermal annealing. PACS Nos.: 64.70.Q-, 64.70.kd, 64.70.kj, 64.70.P-. Nous utilisons ici la methode de simulation de dynamique moleculaire pour etudier l'ordre local et revolution structurelle d'alliages binaires PdAg pendant le processus de cristallisation a partir d'une phase amorphe sous differentes pressions. Le developpement structurel et la transformation de phase, a des pressions de 0,1 et 5 GPa, sont analyses sur la base des variations de la distribution radiale, des parametres d'ordre orientationnel de lien et de la methode de lien de HoneycuttAndersen. Les resultats de la simulation montrent que la haute pression favorise la phase amorphe et a un effet important sur les parametres d'ordre orientationnel de lien dans ce modele de la transformation d'une phase amorphe stable a une phase cristalline stable pendant le recuit isotherme. [Traduit par la Redaction], 1. Introduction Amorphous alloys can be prepared through various nonequilibrium processes, such as rapid solidification, physical vapour deposition, and mechanical alloying [1]. Usually, to avoid the nucleation and growth of [...]

The electronic structure of bulk and slab PbTiO3 perovskite crystal for different layers are investigated using extended-tight binding calculations (GFN1-xTB) with self-consistent charge calculations based on density functional theory. The band structure is calculated for bulk PbTiO3, and the bandgap is determined as 4.3 eV which is in good agreement with experimental data. The bandgaps of slab PbTiO3 for (001) surfaces with five layers from n = 2 to n = 6 are calculated as 2.35, 2.49, 2.65, 2.77 and 2.83 eV, respectively. These results are compared with previous quantum mechanics calculations. Also, the total and partial density of states for five layers with (001) surface and the surface formation energies of slab PbTiO3 are discussed. [ABSTRACT FROM AUTHOR]

The aim of this study was to investigate the crystallization behavior of nano-wire SiO2-Li2O glass ceramic (GC) during the slow cooling process by using density functional theory (DFT). For this purpose, the extended tight-binding with self-consistent charge (SCC-DFTB) was used to investigate the geometric optimization and molecular dynamics (MD) process for model system. The structural development was analysed by radial distribution function (RDF) at determined temperatures. The results show that the system tends to crystallization at lower temperatures and transforms from liquid phase to crystal phase with a slow cooling rate. [ABSTRACT FROM AUTHOR]

This work aims to investigate the effect of Pt concentration on the crystal growth mechanism of a Platinum-Palladium (Pt-Pd) binary alloy system during the annealing process; starting from the amorphous phase to some definite temperatures. The calculations have been performed by using molecular dynamic (MD) simulations. Interatomic interactions are described by the Sutton-Chen type Embedded Atom Potential Energy function. In order to understand the main structural properties at the stable and unstable phases; changes in radial distribution function (RDF) curves versus time have been analyzed for different annealing temperatures. Crystalline type bonded pairs have been determined using MD calculations which is required for the computation of Avrami coefficients and for understanding crystal growth mechanism. The results demonstrate that the increase in concentration of Pt during annealing leads to migration of atoms in the crystal lattice points; elimination of dislocations and formation of perfect crystal structure. [ABSTRACT FROM AUTHOR]