DFT and X-RAY study of structural, electronic, elastic and optical properties in Be_1–XZn_XS alloys depending on vegard’s law

Abstract

Structural, optical and electronic properties and elastic constants of Be 1-x Zn x S alloys have been studied by employing the commercial code Castep based on density functional theory. The generalized gradient approximation and local density approximation were utilized as exchange correlation. Using elastic constants for compounds, bulk modulus, band gap, Fermi energy and Kramers-Kronig relations, dielectric constants and the refractive index have been found through calculations. Apart from these, X-ray measurements revealed elastic constants and Vegard's law. It is seen that results obtained from theory and experiments are all in agreement.

A First-Principles Study of Structural, Electronic and Optical Properties of Be_0.75Zn_0.25S Semiconducting Alloy

“…The bulk modulus computed in the present work is less than all three other calculations. The elastic constants c 12 and c 44 computed in this work using PBE-GGA are in good agreement with the values computed by Glutekin et al [19], while the c 11 shows some deviation.…”

“…We found that both the PBE-GGA and PZ-LDA approaches predict direct bandgap for Be 0.75 Zn 0.25 S. However, the value of the bandgap predicted by PZ-LDA (2.86 eV) is lower than PBE-GGA (3.21 eV), inconsistent with the usual bandgap underestimation by LDA calculations than PBE. The computed bandgaps at Γ and X points of symmetry using PBE-GGA are in agreement with the previous calculations applying the PW-PP and FP-LAPW methods [19,20]; a small deviation is found with FP-LMTO results predicting bandgaps of 2.94 eV and 3.97 eV at Γ and X points. By calculating bowing parameters, Baziz et al [20] predicted a direct-to-indirect bandgap transition from Γ to X at x=0.76.…”

“…Our computed lattice constant using GGA is nearest to FP-LAPW results [20] and higher than two other calculations [19,21]. The deviation of result from the PW-PP method [19] is due to the fact that the lattice constant is computed by assuming Vegard's law in the reported work while we have computed the lattice constant is computed by fitting the E(V) data to Murnaghan equation of state. The bulk modulus computed in the present work is less than all three other calculations.…”

“…1, we also give the values computed by other workers in the absence of experimental findings for the ternary system. For this system, the Plane Wave Pseudopotential (PW-PP) is applied by Glutekin et al [19], the full-potential linear augmented plane wave (FP-LAPW) method is used by Baziz et al [20], and the fullpotential linear muffin-tin orbitals (FP-LMTO) method is applied by Ameri et al [21] to study various properties using GGA. Our computed lattice constant using GGA is nearest to FP-LAPW results [20] and higher than two other calculations [19,21].…”

“…For this system, the Plane Wave Pseudopotential (PW-PP) is applied by Glutekin et al [19], the full-potential linear augmented plane wave (FP-LAPW) method is used by Baziz et al [20], and the fullpotential linear muffin-tin orbitals (FP-LMTO) method is applied by Ameri et al [21] to study various properties using GGA. Our computed lattice constant using GGA is nearest to FP-LAPW results [20] and higher than two other calculations [19,21]. The deviation of result from the PW-PP method [19] is due to the fact that the lattice constant is computed by assuming Vegard's law in the reported work while we have computed the lattice constant is computed by fitting the E(V) data to Murnaghan equation of state.…”