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Structural and Electronic Properties of the BN, BP and BAs in the Different Phases of Zinc-Blende, NaCl and CsCl

100%

Bencherif K., Yakoubi A., Mebtouche H.

Acta Physica Polonica A

2017

vol. 131

issue 2

209-212

In this work we used the first ab initio calculations to study the stability of the binary alloys BN, BP and BAs and their behavior in the different phases of zinc-blende, Nacl and CsCl. The full potential linearized augmented plane wave method was employed within density functional theory. Our results show the difference in the calculated structural properties and the band structure is obtained for the zinc-blende structure. We have investigated the lattice parameters and band gap energies. We also give the valence charge density at a high pressure and the analysis of the density of states.

A Novel Theoretical Study of Elastic and Electronic Properties of M₂CdC (M = Zr, Hf, and Ta) MAX Phases

88%

Mebrek M., Mokaddem A., Doumi B., Yakoubi A., Mir A.

Acta Physica Polonica A

2018

vol. 133

issue 1

76-81

In this study, we have investigated the structural, electronic, and elastic properties of the M₂CdC (M = Ta, Zr, and Hf) MAX phases, using the first-principle methods based on the density functional theory. The calculated formation energies revealed that these compounds are thermodynamically stable in the hexagonal MAX phase. The stability is confirmed by the elastic constants and the conditions of mechanical stability criterion. Also, we have determined the bulk and shear modules of the Young modulus and the Poisson coefficient. The band structures indicate that the three materials are electrically conductive. The chemical bond in M₂CdC is covalent-ionic in nature with the presence of metallic character. For the density of states the hybridization peak between M d and C p occurs in the lower energy range. We have found that there is no gap for these materials due to the existence of a maximum peak of DOS around Fermi level.

First-Principles Study of the Structural, Electronic, Magnetic and Thermal Properties of the Cr Doped Ge₆Mn₂Te₈ and Ge₆Fe₂Te₈ Systems

64%

Semari F., Baki N., Khachai H., Yakoubi A., Méçabih S., Khenata R., Shankar A., Rai D., Bouhemadou A.

Acta Physica Polonica A

2017

vol. 132

issue 4

1242-1250

First-principles calculations have been used to study the structural, electronic, magnetic, and thermal properties of the Cr doped Ge₆Mn₂Te₈ and Ge₆Fe₂Te₈ systems. The calculations were performed using the full-potential linearized augmented plane wave plus local orbitals (FP-LAPW + LO) method based on the spin-polarized density functional theory. Additionally, the electronic exchange-correlation potential is approximated using the spin generalized gradient approximation. The structural properties of the Ge₅Mn₂CrTe₈ and Ge₅Fe₂CrTe₈ alloys are indicated by their corresponding lattice constants, values of the bulk moduli and their pressure derivatives. An analysis of the band structures and the densities of states indicate that for both alloys, they present nearly half-metallic ferromagnetism character. The band structure calculations are used to estimate the spin-polarized splitting energies, Δp_{x}(d) and Δp_{x}(pd) produced by the 3d Mn, 3d Fe and 3d Cr doped states as well as the s(p)-d exchange constants, N₀α (conduction band) and N₀β (valence band). It is observed that the p-d hybridization reduces the magnetic moment of the Mn and Fe atoms from their atomic charge values and create small local magnetic moments on the nonmagnetic Ge and Te sites. Furthermore, the calculations of the charge density indicate that both compounds have ionic bonding character. Through the quasi-harmonic Debye model, the effects of pressure P and temperature T on the bulk modulus B, the primitive cell volume V/V₀, the Debye temperature θ_{D}, the Grüneisen parameter γ, the heat capacity C_{V}, the entropy S, as well as the thermal expansion coefficient, α of the Ge₆Mn₂Te₈, Ge₅Mn₂CrTe₈, Ge₆Fe₂Te₈ and Ge₅Fe₂CrTe₈ alloys are predicted.

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3 Acta Physica Polonica A

1 2018

2 2017

3 Yakoubi A.

1 Baki N.

1 Bencherif K.

1 Bouhemadou A.

1 Doumi B.

1 Khachai H.

1 Khenata R.

1 Mebrek M.

1 Mebtouche H.

1 Mir A.

1 Mokaddem A.

1 Méçabih S.

1 Rai D.

1 Semari F.

1 Shankar A.

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Structural and Electronic Properties of the BN, BP and BAs in the Different Phases of Zinc-Blende, NaCl and CsCl

A Novel Theoretical Study of Elastic and Electronic Properties of M₂CdC (M = Zr, Hf, and Ta) MAX Phases

First-Principles Study of the Structural, Electronic, Magnetic and Thermal Properties of the Cr Doped Ge₆Mn₂Te₈ and Ge₆Fe₂Te₈ Systems