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First principle calculations of electronic and magnetic properties of Mn-doped CdS (zinc blende): a theoretical study

Ahmed N., Nabi A., Nisar J., Tariq M., Javid M. A., Nasim M. H.

Materials Science Poland

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2017

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Vol. 35, No. 3

479--485

EN

The electronic structure and magnetic properties of Mn doped zinc blende cadmium sulfide Cd1-xMnxS (x = 6.25 %) have been studied using spin-polarized density functional theory within the framework of Generalized Gradient Approximation (GGA), its further corrections including Hubbard U interactions (GGA + U) and a model for exchange and correlation potential Tran Blaha modified Becke-Johnson (TB-mBJ). Ferromagnetic interactions have been observed between Mn atoms via S atom due to strong p-d hybridization. The magnetic moments on Mn and its neighboring atoms have also been studied in detail using different charge analysis techniques. It has been observed that p-d hybridization reduced the value of local magnetic moment of Mn in comparison to its free space charge value and produced small local magnetic moments on the nonmagnetic S and Cd host sites. The magnetocrystalline anisotropy in [1 0 0] and [1 1 1] directions as well as exchange splitting parameters Noα and Noβ have been analyzed to confirm that ferromagnetism exists. We conclude that the ferromagnetic phase in Mn-doped CdS is not stable in “near” configuration but it is stable for “far” configuration. Mn doped CdS is a p-type semiconductor and the d-states at the top of the valence band edge give a very useful material for photoluminescence and magneto-optical devices.

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First-principle investigations of structural and electronic properties of TMAl (TM = Fe, Co, and Ni) transition metal aluminides

Bendouma D, Allel M., Mustapha I. B., Miloud B., Abdelkader T.

Materials Science Poland

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2015

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Vol. 33, No. 2

251--258

EN

In the present work, we have investigated the structural and electronic properties of TMAl (TM = Fe, Co, and Ni) transition metal aluminides in the B2 structure, using first-principle calculations of the density functional theory (DFT) based on the linearized augmented plane wave method (FP-LAPW) as implemented in the WIEN2k code, in which the energy of exchange and correlation are treated by the generalized gradient approximation (GGA), proposed in 1996 by Perdew, Burke and Ernzerhof (PBE). The ground state properties have been calculated and compared with other calculations, and the electronic structures of all FeAl, CoAl, and NiAl compounds exhibited a metallic behavior. It was depicted that the density of states is characterized by the large hybridization between the s-p (Al) and 3d (Fe, Co, and Ni) states, which creates the pseudogap in the region of anti-bonding states. Moreover, the band structures of FeAl, CoAl, and NiAl are similar to each other and the difference between them is in the energy level of each band relative to the Fermi level.

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Ab-initio study of structural, elastic, electronic and thermodynamic properties of BaxSr1-xS ternary alloys

Chelli S., Touam S., Hamioud L., Meradji H., Ghemid S., Hassan F. E.

Materials Science Poland

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2015

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Vol. 33, No. 4

879--886

EN

The structural, elastic, electronic and thermodynamic properties of BaxSr1-xS ternary alloys have been investigated using the full-potential (linearized) augmented plane wave method. The ground state properties, such as lattice constant, bulk modulus and elastic constants, are in good agreement with numerous experimental and theoretical data. The dependence of the lattice parameters, bulk modulus and band gap on the composition x was analyzed. Deviation of the lattice constant from Vegard's law and the bulk modulus from linear concentration dependence (LCD) was observed. The microscopic origins of the gap bowing were explained by using the approach of Zunger et al. The thermodynamic stability of BaxSr1-xS alloy was investigated by calculating the excess enthalpy of mixing, Delta H-m and the calculated phase diagram showed a broad miscibility gap with a critical temperature.

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Structural and elastic properties of TiN and AlN compounds: first-principles study

Fodil M, Mounir A, Ameri M., Baltache H, Bouhafs B, Al-Douri Y, Ameri I

Materials Science Poland

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2014

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Vol. 32, No. 2

220--227

EN

First-principles calculations of the lattice constants, bulk modulus, pressure derivatives of the bulk modulus and elastic constants of AlN and TiN compounds in rock-salt (B1) and wurtzite (B4) structures are presented. We have used the fullpotential linearized augmented plane wave (FP-LAPW) method within the density functional theory (DFT) in the generalized gradient approximation (GGA) for the exchange-correlation functional. Moreover, the elastic properties of cubic TiN and hexagonal AlN, including elastic constants, bulk and shear moduli are determined and compared with previous experimental and theoretical data. Our results show that the structural transition at 0 K from wurtzite to rock-salt phase occurs at 10 GPa and -26 GPa for AlN and TiN, respectively. These results are consistent with those of other studies found in the literature.

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Electronic structure and possible martensitic transformation in Ni2FeIn alloy

Gu Y., Xue F, Zhao G, Liu G., Liu Y., Li S.

Materials Science Poland

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2014

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Vol. 32, No. 3

396—401

EN

The electronic structure and magnetic properties of Heusler alloys (Ni2FeIn) have been studied by first principle calculations. The possible tetragonal martensitic transformation has been predicted and the structure optimization was made on cubic austenitic Ni2FeIn in Cu2MnAl type. The equilibrium lattice constant of austenitic Ni2FeIn is 6.03 A° . In tetragonal phase, the global energy minimum occurs at c=a = 1.29. The corresponding equilibrium lattice constants for martensite Ni2FeIn are a = b = 5.5393 °A and c = 7.1457 A° , respectively. In the austenitic phase, EF is located at the peak in the minority DOS for c=a = 0.96 to 1.20, but in the martensitic phase, EF moves to the bottom of the valley in the minority DOS, reducing the value of N(EF ) effectively. Both austenitic and martensitic phases are ferromagnetic and the Ni and Fe partial moments contribute mainly to the total moments. Therefore, the martensitic transformation behavior in Ni2FeIn is predicted.

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Nature of gallium deep centres in lead telluride based semiconductors

Petrenko T. L., Plyatsko S. V.

Opto-Electronics Review

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2010

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Vol. 18, No. 3

310-317

EN

Doped with Ga lead telluride was taken as a model object to explain the nature of group-III deep levels in IV-VI semiconductors and to elucidate the vapour phase doping mechanism. For this goal, interaction of various gallium-containing molecules with defect-free crystal as well as with native defects in PbTe was considered. Formation energies for different point defects created in PbTe as a result of interaction the Ga2Te molecules, Ga2 dimers and single Ga atoms with a host crystal were calculated using density functional theory. Particularly GaPb and Gai together with formation of accompanied self interstitials Pbi in various charge states were examined. In addition we propose the new type of defects - the impurity complex (2Ga)Pb which looks like <111>-oriented gallium dumbbell. Calculations suggest the double donor behaviour and DX-like properties of this defect together with extremely low formation energy values. Namely, (2Ga)Pb centres are preferably formed under Ga2Te doping while (Ga2)Pb+Pbi ones are formed under Ga2 or Ga doping. In all cases, formation energies are negative and resulting defect concentration is determined by reaction kinetics only. Mechanisms of the lead vacancy compensation with the vapour phase doping are considered as well.