This study primarily focuses on examining the structural, electronic, optical, and elastic characteristics of the ternary alloys B1−xGaxBi. To thoroughly investigate these attributes, we conducted calculations using the “full potential linearized augmented plane wave (FP-LAPW)” method within the framework of “density functional theory (DFT)”. Our approach involved employing “generalized gradient approximations (GGA) and modified Becke-Johnson (mBJ) potential”. Initially, we scrutinized the structural, electronic, optical, and elastic properties of the binary compounds BBi and GaBi. Subsequently, we expanded our analysis to ternary alloys B1−xGaxBi (x = 0, 0.25, 0.5, 0.75, and 1). Furthermore, we investigated the connection between composition and structure, as well as electrical properties. Interestingly, deviations from linearity were observed in both the bulk modulus (B) and the lattice constant. In addition, the elastic constants obtained confirm the mechanical stability of the studied alloy. We found that the obtained results match with both existing experimental and theoretical data. It has been shown that the ternary alloys B1−xGaxBi are classified as brittle materials, whereas the binary compounds BBi and GaBi are classified as ductile materials.

Both electronic as well as magnetic characteristics of Co 1-x Fe x MnSb ( x = 0, 0.25, 0.50, 0.75, 1) composite have been studied by employing the first principle (FP) study. The FP calculation was attained using the density functional theory (DFT). The exchange–correlation term has been examined inside the generalized gradient approximation (GGA), as implemented in the Wien2k code. According to predictions, the type 3 structure of atoms will be the tremendous, optimum, and have the smallest amount of energy. The formation energy of CoMnSb and FeMnSb was minimum so it demonstrates that these alloys are optimized. CoMnSb and FeMnSb are half-metallic (HM) having the value of magnetic moment 3µ B and 2µ B , respectively in good agreement with the Slater-Pauling rule. These results suggest that the Mn atoms are the primary source of the magnetic moment. The values of elastic constants were determined by the crystal structure’s symmetry. Additionally, the bulk modulus B , shear modulus G , Young’s modulus E , as well as Poisson’s ratio v have been determined using the Voigt-Reuss-Hill (VRH) method. Both examined compounds, CoMnSb and FeMnSb, have computed B/G ratios higher as compared to 1.75, indicating that these alloys are malleable.

Using density functional and and Boltzmann transport theories, we investigate the thermoelectric transport properties ZrCo1-xIrxSb (x = 0, 0.125, 0.25, 0.375, 0.5, 0.625, 0.75, 0.875, 1) half-Heusler alloys. The current work found that increasing the concentration of iridium ( Irx ) from x = 0 to 0.375 in the ZrCo1-xIrxSb alloys from room temperature to 800 K significantly decreased thermal and electrical conductivity due to a shorter relaxation time. Furthermore, our results show that ZrCo0.625Ir0.375Sb has the highest Seebeck coefficient (353.93 mu V/K ) at 300 K, thereby boosting its thermoelectric performance. Interestingly, the thermoelectric figure of merit (ZT) has exceptional value 1.01 by applying 25% (x = 0.25) of atomic doping of iridium (Ir) with a carrier concentration of n=1.47 & sdot;1020cm-3 at 1000 K and 37.5% (x = 0.375) of atomic doping of iridium (Ir) with a carrier concentration of n=7.23 & sdot;1019cm-3 at 800 K. Calculations present important results on the suitability of the studied alloys for thermoelectric applications.

The present study reports the properties of pressure-induced phase transition, electronic and optical of phosphides XSiP2 under pressure in chalcopyrite, sodium chloride (rock salt), and Wurtzite phases. The study shows the chalcopyrite phase as the most stable phase among the other studied phases. The obtained structural parameters in the chalcopyrite and rock-salt phases reasonably agree with the literature. The computed band structures revealed a semiconductor behavior in chalcopyrite structure and metallic behavior for rock- salt and wurtzite structures. In the energy range of 0 to 30 eV, optical parameters such as the real and imaginary parts of the dielectric constant, refractive index, and reflectivity are calculated and compared with existing data. Our optical properties findings are predictive for the rock-salt and wurtzite phases. Since no results are available in the literature, these results may serve as references for other theoretical and experimental studies. The calculations are performed by employing the “full-potential linearized augmented plane wave (FP-LAPW) method within density functional theory (DFT).”

We explored the pressure-induced structural phase transitions and elastic properties of AuMTe2 (M = Ga, In) using the full-potential linearized augmented plane wave method within the framework of density functional theory, applying both generalized gradient and local density approximations. Thermodynamic properties were further assessed through the quasi-harmonic model. We determined the transition pressures for the phase shift from the chalcopyrite structure to the NaCl rock-salt phase in both AuGaTe2 and AuInTe2. Additionally, we calculated and analyzed mechanical properties, such as bulk modulus, shear modulus, Young's modulus, Poisson's ratio, elastic anisotropy, ductility versus brittleness, and hardness for the polycrystalline forms of AuMTe2 (M = Ga, In). The study also examined how temperature and pressure affect the Debye temperature, heat capacities, thermal expansion, entropy, bulk modulus, Grüneisen parameter, and hardness, utilizing the quasi-harmonic Debye model.

In this paper, we present computational results of the structural, mechanical, electronic, elastic, and thermal properties of the binary intermetallic compound Ga3Sc by using the full potential linearized augmented plane wave method. The total energy calculations reveal that the cubic L1(2) structure for Ga3Sc is more stable than the tetragonal D0(22) and D0(23) structures. The ground-state structural and mechanical properties including the lattice constants (a, c), bulk modulus (B) and its pressure derivative (B') are estimated by different approximations. The single-crystal elastic constants C-ij are calculated. Similarly, the shear modulus (G(H)), Young's modulus (E), Poisson's ratio (nu), and the elastic anisotropy factor (A) are also derived for polycrystalline Ga3Sc using the Voigt-Reuss-Hill approximations. Analysis of the calculated elastic constants Cij, B/G ratios and the Cauchy pressure (C-12-C-44) shows that these compounds are mechanically stable and brittle in nature. The electronic and bonding properties are discussed from the calculations of band structures, densities of states and electron charge densities. The quasi-harmonic Debye model is used to predict thermodynamic properties of Ga3Sc at different temperatures and pressures.

In the present computational study, we have explored the structural, electronic and optical properties of ZnTe, CdTe and HgTe binary compounds and their ternary alloys ZnxCd1-xTe, ZnxHg1-xTe and CdxHg1-xTe as well as their ordered quaternary ZnxCdyHg1-x-yTe alloys using the full potential linearized augmented plane wave (FP-LAPW) method based on the density functional theory. We have numerically estimated the total energies, the lattice parameters, the bulk moduli and their first pressure derivative using the generalized gradient approximation (GGA). The band structure is computed using the modified Becke-Johnson (TB-mBJ) approximation. Results of our study show a nonlinear dependence of the composition on the lattice constant, bulk modulus and band gap for the binary and ternary compounds as well as for the quaternary alloys. Additionally, the dielectric function, the refractive index and the loss energy were also reported. The pressure effect on the band gap energy and optical properties were also investigated and reported. Our results are in good agreement with experimental values and theoretical data available in the literature.

Predicted results of the structural, electronic and optical properties of the cubic zinc-blende phase of BN, BAs and BP binary compounds and their related ternary and quaternary alloys are presented. The density functional theory (DFT) within full potential linearized augmented plan wave (FP-LAPW) is employed. Different exchange correlation approximations were used to calculate the structural properties as well as the total energies, lattice parameters, bulk modulus and its first pressure derivative. The electronic band structures were treated with the local density approach and Tran Blaha modified Beck-Johnson (TB-mBJ) approximation. A quadratic fit of the lattice parameter, bulk modulus and band gap was performed, where a nonlinear variation with the composition x and y is found. Moreover, the optical properties have been investigated, where the dielectric behavior, the refractive index variations and the loss energy were studied. Furthermore, the electronic and optical properties were computed under hydrostatic pressure. Our results showed great agreement with the previous available experimental and theoretical data found in the literature.

In this work, we studied the structural, electronic, elastic and thermodynamic properties of the ternary AgGaTe2 and AgInTe2 chalcopyrite semiconductors and their mixed crystals AgIn1-xGaxTe2 using the full-potential linearized augmented plane wave (FP-LAPW) method within density functional theory (DFT). The optimized equilibrium structural parameters (a, c and u) are in good agreement with the experimental and theoretical results obtained by other researchers. The electronic-structure calculations show that the ternary compounds are direct band gap semiconductors. We modeled the AgIn1-xGaxTe2 alloys at some selected compositions with ordered structures described in terms of periodically repeated supercells. The effects of the composition (x) on lattice parameters, bulk moduli and band gaps were investigated. Furthermore, the thermodynamic stability of these alloys was investigated by calculating the excess enthalpy of mixing Delta Hm as well as the phase diagram.

First-principles calculations were used to calculate the structural, electronic and half-metallic ferromagnetism of Mn2RuGe1-xSnx (x=0, 0.25, 0.50, 0.75, 1) Heusler alloys. The Hg2CuTi-type structure is found to be energetic more than Cu2MnAl-type structure for both Mn2RuGe and Mn2RuSn compounds. The calculated lattice constants for Mn2RuGe and Mn2RuSn are 5.91 Å and 6.17 Å, respectively. The electronic band structures and density of states of Mn2RuGe show a half metallic character with total magnetic moments, 2 μB per formula unit that are in good agreement with Slater-Pauling rule with indirect band gap, 0.31 eV along the direction Γ –X. It is observed that the total magnetic moment per cell increases as Sn concentration increases in the Heusler alloys.

First-principles density functional theory approach is adopted to determine the electronic, magnetic and structural characteristics of the Mn2CoAs1-xAlx (x = 0,0.25,0.50,0.75) Heusler alloys. The computations are carried out by WIEN2k code based on full-potential linearized augmented plane wave method (FP-LAPW). Moreover, the exchange-correlation energy functional is treated at the level of the generalized gradient approximation (GGA). Analysis of our computed results of the electronic band structure, as well as the density of states of the Mn2CoAs compound, show it a stable and half-metallic material with an energy band gap value of 0.48 eV. The calculated spin gap values are: 0.627 eV, 0.22 eV and 0.188 eV for Mn2CoAs0.75Al0.25, Mn2CoAs0.50Al0.50 and Mn2CoAs0.25Al0.75 respectively. Furthermore, the calculated total magnetic moment of the Mn2CoAs (4 mu B) is found to be in agreement with the Slater-Pauling rule. Thus, our calculations show the Mn2CoAs1-xAlx (x = 0, 0.25, 0.50, 0.75) Heusler alloys potential materials for near future applications in spintronic because of their half-metallic ferromagnetism property.

In the present work, we have investigated the structural, electronic and optical properties of SrF2 and CdF2 and their ternary mixed SrxCd1-xF2 alloys at some selected concentrations x (x = 0.25, 0.50, 0.75 and 1). The parent compounds SrF2 and CdF2 crystallize in Fm-3m space group, whereas the alloys adopt the cubic structure with Pm-3m space group for the composition x = 0.25 and 0.75 and the tetragonal structure with space group P4/mmm for x = 0.50. The calculations were performed using the full-potential linearized augmented plane wave (FP-LAPW) method. The exchange-correlation potential was handled with Wu and Cohen GGA approximation (WC-GGA). Moreover, the Engel-Vosko's (EV-GGA) formalism and the modified Becke Johnson (mBJ) approximation were also applied to improve the electronic band structure calculations. The computed structural parameters for SrF2 and CdF2 such as the equilibrium lattice constants and the bulk moduli are in good agreement with the available experimental and theoretical data. It is found that the lattice parameters increase with increasing composition (x) while the bulk modulus decreases for SrxCd1-xF2 alloys. The calculated band structures reveal an indirect band gap (W-G), (X-G) and (M-G) for CdF2, SrF2 and SrxCd1-xF2 for x = 0.25, 0.75 and x = 0.5, respectively. The optical constants, including the dielectric function, refractive index, reflectivity, absorption, extinction coefficient and the energy loss function were calculated using both WC-GGA and mBJ schemes for a radiation up to 40 eV. This is the first quantitative theoretical prediction of the optical properties for these alloys that requires experimental confirmation.

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, Delta(x)(d) and Delta(x)(pd) produced by the 3d Mn, 3d Fe and 3d Cr doped states as well as the s(p)-d exchange constants, N-0 alpha (conduction band) and N-0 beta (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/V-0, the Debye temperature theta(D), the Gruneisen parameter gamma, the heat capacity CV, the entropy S, as well as the thermal expansion coefficient, alpha of the Ge 6 Mn 2 Te 8, Ge5Mn2CrTe8, Ge6Fe2Te8 and Ge5Fe2CrTe8 alloys are predicted.

Bonding nature as well as structural, optoelectronic and thermal properties of the cubic X Mg 2 O 4(X = Si , Ge ) spinel compounds have been calculated using a full-potential augmented plane-wave plus local orbitals (FP-APW+lo) method within the density functional theory. The exchange-correlation potential was treated with the PBE-GGA approximation to calculate the total energy. Moreover, the modified Becke–Johnson potential (TB-mBJ) was also applied to improve the electronic band structure calculations. The computed ground-state parameters (a, B, B′ and u) are in excellent agreements with the available theoretical data. Calculations of the electronic band structure and bonding properties show that these compounds have a direct energy band gap (Γ-Γ) with a dominated ionic character and the TB-mBJ approximation yields larger fundamental band gaps compared to those obtained using the PBE-GGA. Optical properties such as the complex dielectric function ε(ω), reflectivity R(ω) and energy loss function L(ω), for incident photon energy up to 40 eV, have been predicted. Through the quasi-harmonic Debye model, in which the phononic effects are considered, the effects of pressure P and temperature T on the thermal expansion coefficient, Debye temperature and heat capacity for the considered compounds are investigated for the first time.

We theoretically study the structural, elastic, and electronic properties as well as the pressure induced solid-solid phase transitions of iridium mononitride (IrN) by using the full potential linear muffin-tin orbital method with the local density approximation as exchange and correlation functional. Six different crystal structures; the zinc-blende (B3), rock salt (B1), wurtzitc (B4), NiAs (B8(1)), CsCl (B2), and the tungsten carbide (B-h) have been considered. The transition pressures at which IrN undergoes the structural phase transition from (B3) to (B81), (B1), (Bh), and (B2) phases are calculated. The elastic constants of IrN in its different structures are determined by using the total energy variation with strain technique. The ductility mechanism is discussed via the calculated elastic constants C-ij. The Debye temperature of this compound in its stable (B3) phase is estimated from the average sound velocity. Band structure reveals that this compound has a metallic character. The obtained results classified IrN as superhard material in its (B3) phase. To our knowledge this is the first quantitative theoretical prediction of the elastic and high-pressure properties for this compound and still awaits experimental confirmations.

The full-potential linearized augmented plane-wave plus local orbitals method with the generalized gradient approximation for the exchange–correlation potential (FP-APW+lo-GGA) is used to predict the structural, elastic and high pressure properties of YX with X=S, Se and Te. Ground state properties such as lattice constant, bulk modulus and its pressure derivative are obtained. The pressures at which these compounds undergo structural phase transition from NaCl-type to CsCl-type phases are calculated. The elastic constants and their pressure dependence are calculated using the total energy variation with strain technique. The shear modulus, Young’s modulus, Poisson’s ratio and Lamé’s coefficients are estimated in framework of Voigt–Reuss–Hill approximation for polycrystalline YX aggregates. The Debye temperature is estimated from the average sound velocity. To our knowledge this is the first quantitative theoretical prediction of the elastic and high pressure properties for these compounds and still awaits experimental confirmations.

We have performed accurate ab initio total energy calculations using the full-potential linear augmented plane wave plus local orbitals method with the local density approximation for the exchange–correlation potential to investigate the systematic trends for structural and elastic properties of the cubic LaFe4A12 skutterudites’ family depending on the type of A pnicogen atom (A stands for P, As and Sb). The calculated equilibrium lattice constants and internal free parameters are in good agreement with the experimental results. For the first time, the numerical estimates of the independent elastic constants and their pressure dependence are performed using the total energy variation as function of strain technique. Isotropic elastic parameters and related properties, namely bulk modulus, shear modulus, Young’s modulus, Poisson’s ratio, Lamé’s coefficients, average sound velocity and Debye temperature, are estimated in the framework of the Voigt–Reuss–Hill approximation for ideal polycrystalline LaFe4A12 aggregates.

The structural, elastic, electronic, and optical properties of cubic spinel MgIn2S4 and CdIn2S4 compounds have been calculated using a full relativistic version of the full-potential linearized-augmented plane wave with the mixed basis FP/APW+lo method. The exchange and correlation potential is treated by the generalized-gradient approximation (GGA). Moreover, the Engel–Vosko GGA formalism is also applied to optimize the corresponding potential for band structure calculations. The ground state properties, including the lattice constants, the internal parameter, the bulk modulus, and the pressure derivative of the bulk modulus are in reasonable agreement with the available data. Using the total energy-strain technique, we have determined the full set of first-order elastic constants Cij and their pressure dependence, which have not been calculated or measured yet. The shear modulus, Young’s modulus, and Poisson’s ratio are calculated for polycrystalline XIn2S4 aggregates. The Debye temperature is estimated from the average sound velocity. Electronic band structures show a direct band gap (Г–Г) for MgIn2S4 and an indirect band gap (K–Г) for CdIn2S4. The calculated band gaps with EVGGA show a significant improvement over the GGA. The optical constants, including the dielectric function ε(ω), the refractive index n(ω), the reflectivity R(ω), and the energy loss function L(ω) were calculated for radiation up to 30eV.

Structural, electronic, elastic and optical properties of the cubic-antiperovskite-type ANSr(3). with A=As, Sb and Bi, are studied under pressure effect using the full-relativistic version of the full-potential augmented plane wave plus local orbitals method (FP-APW+lo). The exchange-correlation potential is treated by the generalized gradient approximation within the scheme of Perdew, Burke and Ernzerhof (GGA-PBE). Also we have used Engel and Vosko GGA formalism (GGA-EV) to improve the band gap results. The calculated bulk properties, including lattice constants, bulk moduli and their pressure derivatives are in reasonable agreement with the available data. The elastic constants C-ij and their pressure dependences are calculated using the total energy-strain technique. The shear modulus, Young's modulus, Poisson's ratio and Lame's coefficients are estimated in the framework of the Voigt-Reuss-Hill approximation for ideal polycrystalline ANSr(3) aggregates. The Debye temperature is estimated from the average sound velocity. Energy band structures show that the investigated materials are direct energy band gap semiconductors. Analysis of the density of states and charge density distribution shows that the bonding is a mixture of covalent and ionic character. For the first time, the real and imaginary parts of the dielectric function epsilon(omega), the refractive index n(omega), the reflectivity R(omega) and the energy loss function L(omega) are calculated for radiation up to 18 eV. (C) 2010 Elsevier B.V. All rights reserved.

First-principle calculations of structural, elastic and high pressure properties of antiperovskites XNBa3 (X=As, Sb) are performed, using the full-potential linear muffin-tin orbital (FP-LMTO) method. The local density approximation (LDA) is used for the exchange-correlation (XC) potential. Results are given for lattice constant, bulk modulus and its pressure derivatives. We have determined the elastic constants C11, C12 and C44 and their pressure dependence. We derived shear moduli, Young's modulus, Poisson's ratio and Lamé's constants for ideal polycrystalline XNBa3 aggregates. By analyzing the ratio of the bulk to shear moduli, we conclude that XNBa3 compounds are brittle in nature. We estimated the Debye temperature of XNBa3 from the average sound velocity. This is the first quantitative theoretical prediction of the elastic properties of AsNBa3 and SbNBa3 compounds, and it still awaits experimental confirmation.