Physical Properties of Yttrium-Rhodium and Yttrium-Copper B2-Type Rare Earth Intermetallic Compounds: First Principles Study

The electronic structure of B2-YCu and YRh intermetallic compounds which crystallize in the CsCl structure has attracted the attention of the scientific world because of their excellent mechanical properties. The advantage of studying these materials is to answer of some industrial request in the materials that resist for high temperature and high oxidation resistance. However, high ductility has been observed in these compounds at room temperature. In this present work, we employed ab initio calculation methods while basing on the full-potential linearized augmented plane wave (FP-LAPW) method within density functional theory implanted in the Wien-2 k code, which is used to examine the various properties of these materials (YCu, YRh) like structural, electronic, and elastic properties. The results obtained are in good agreement with those found in other theoretical studies and experimental data

Influence of the interface morphology on the magnetization of Magnetic/Non-Magnetic (Fe/Cu) multilayers: a Monte Carlo investigation

A Monte Carlo investigation was used to study the magnetization of a Heisenberg multilayers system. Our model consists of an alternate staking of Magnetic and Non-Magnetic layers (M/NM) with disordered interfaces. The results indicate that the magnetization of multilayers M/NM depends on the atomic composition, the interface morphology and the exchange interactions at the interface.A Monte Carlo investigation was used to study the magnetization of a Heisenberg multilayers system. Our model consists of an alternate staking of Magnetic and Non-Magnetic layers (M/NM) with disordered interfaces. The results indicate that the magnetization of multilayers M/NM depends on the atomic composition, the interface morphology and the exchange interactions at the interface

Mössbauer study and Monte Carlo simulations of the hyperfine field distribution in Magnetic/Non-Magnetic (M/NM) multilayers

Using a Monte Carlo numerical method, we perform a complementary analysis of the hyperfine field distribution in Magnetic/Non-Magnetic (M=Fe/NM=Cu) multilayers and a comparison with Mössbauer experiment results of [Fe(40)=Cu(20)]20 multilayers. From differing relaxation rates for spins with few near neighbor spins and particularly those located at the interface, the Mössbauer result can be simulated. Our model consists of an alternate stacking of magnetic and non-magnetic layers (MnM/NMnNM) with disordered interface. The simulation results confirm that the concentration of interface alloys (M1-xNMx) and magnetic layer thickness modify systemically the magnetization distribution in the M/NM multilayers. The result is in agreement with Mössbauer experimental analysis

Atomic scale simulation of epitaxial growth: Cases of GaAs/GaAs and CdTe/GaAs

We present a kinetic Monte Carlo model describing the growth by molecular beam epitaxy (MBE) of semiconductor compounds and including a local photoemission model with reflection high-energy electron diffraction (RHEED) intensity for comparison. We investigate the cases of both homoepitaxial and heteroepitaxial growth. The valence force field approximation is used for the strain energy calculations in mismatched thin films In homoepitaxial growth of GaAs, we have study the variations of photoemission current and RHEED intensity and examined the GaAs morphology. In high lattice mismatch heteroepitaxial growth (CdTe/GaAs), we have shown the formation of grooves corresponding to (111) facets, precursor to the formation of misfit defects.We present a kinetic Monte Carlo model describing the growth by molecular beam epitaxy (MBE) of semiconductor compounds and including a local photoemission model with reflection high-energy electron diffraction (RHEED) intensity for comparison. We investigate the cases of both homoepitaxial and heteroepitaxial growth. The valence force field approximation is used for the strain energy calculations in mismatched thin films In homoepitaxial growth of GaAs, we have study the variations of photoemission current and RHEED intensity and examined the GaAs morphology. In high lattice mismatch heteroepitaxial growth (CdTe/GaAs), we have shown the formation of grooves corresponding to (111) facets, precursor to the formation of misfit defects

THE IRON SPIN TEXTURE IN ANNEALED AMORPHOUS Fe/Tb MULTI-LAYERS

Fe/Tb multilayers have been obtained by vacuum evaporation with Tb-layer thickness fixed to 40Å and amorphous Fe-layer thickness fixed to 19Å. 57Fe-Mössbauer spectrometry was used to obtain information on the structure and the spin texture of the multilayers before and after annealing at 530K for different durations of the annealing. The Mössbauer results indicate that the Perpendicular Magnetic Anisotropy (PMA) was stabilised and reinforced after annealing.Fe/Tb multilayers have been obtained by vacuum evaporation with Tb-layer thickness fixed to 40Å and amorphous Fe-layer thickness fixed to 19Å. 57Fe-Mössbauer spectrometry was used to obtain information on the structure and the spin texture of the multilayers before and after annealing at 530K for different durations of the annealing. The Mössbauer results indicate that the Perpendicular Magnetic Anisotropy (PMA) was stabilised and reinforced after annealing

Nucleation and growth mechanism of nickel electrodeposited on ITO substrate in nitrate and chloride electrolytes: Comparative study

In this work, we reported a comparative study of nickel electrodeposition mechanism on indium tin oxide (ITO) from two mediums. The nitrate electrolyte contains 0.01 M of nickel nitrate hexahydrate (Ni (NO3)2, 6H2O) with 0.1M of potassium nitrate (KNO3)and chloride bath was a mixture of 0.01 M (NiCl2, 6H2O) with 0.1 M of potassium chloride (KCl). The electrochemical techniques cyclic voltammetry (CV) and the chronoamperometry (CA) revealed that the electrodeposition of nickel (Ni) at a negative potential around -1.1 V versus SCE (saturated calomel electrode) is quasi-reversible reaction controlled by the diffusion process in the two mediums. The experimental current transient curves are compared to those calculated from Scharifker-Hills models; it was found that the nucleation and growth of Ni on the ITO substrate follows an instantaneous three-dimensional (3D) mechanism in the two solutions, which was confirmed by the micrographs of SEM analysis. The X-ray diffraction characterization of nickel thins films elaborated by chronoamperometry on ITO substrate had shown a cubic crystal structure whatever the electrolyte composition. However, in nitrate solution the formation of a nickel oxide was identified

Aging characterization of metals for exhaust systems

The mechanical characteristics of four materials used in automotive exhaust systems have been compared after an aging treatment to evaluate the combined effects of thermo-mechanical fatigue and corrosion. For this purpose, an experimental aging procedure has been developed. This procedure is composed of chemical, thermal and mechanical cycles, which are combined and repeated to simulate the actual operating conditions of automotive exhaust systems. Three austenitic steels (AISI 309, AISI 316Ti, and AISI 321) and a nickel-based alloy (Inconel 625) are tested. The results show that Inconel 625 and AISI 309 are less affected by the aging process than the other material

Electronic structure of the Magnesium hydride molecular ion

In this paper, using a standard quantum chemistry approach based on pseudopotentials for atomic core representation, Gaussian basis sets, and effective core polarization potentials, we investigate the electronic properties of the MgH$^+$ ion. We first determine potential energy curves for several states using different basis sets and discuss their predicted accuracy by comparing our values of the well depths and position with other available results. We then calculate permanent and transition dipole moments for several transitions. Finally for the first time, we calculate the static dipole polarizability of MgH$^+$ as function of the interatomic distance. This study represents the first step towards the modeling of collisions between trapped cold Mg$^+$ ions and H$_2$ molecules.Comment: submitted to J. Phys. B, special issue on Cold trapped ion