First principles calculations of structural, electronic and thermodynamic properties of SrS, SrSe, SrTe compounds and SrS1−xSex alloy

AbstractThe ab initio full potential linearized augmented plane wave (FP-LAPW) method within density functional theory was applied to study the structural and electronic properties of the compounds SrS, SrSe, SrTe and their alloy SrS1−xSex in the NaCl structure. Results are obtained using both the local density approximation (LDA) and the generalized gradient approximation (GGA) for the exchange-correlation potentials. The ground-state properties, like lattice constant and bulk modulus obtained from our calculations agree very well with experimental and other theoretical calculations. We present the main features of electronic properties, where the electronic band structure shows that the fundamental energy gap is indirect (Γ→X). Moreover the alternative form of GGA proposed by Engel and Vosko (GGA-EV) is also used for band structure calculations. Results obtained with this approximation show that significant improvement over other theoretical work are closer to the experimental data. The effect of composition on lattice parameter and bulk modulus was investigated.Deviations of the lattice constant from Vegard’s law and the bulk modulus from linear concentration dependence were observed for the alloy. Moreover, the microscopic origins of the gap bowing were explained. In addition the thermodynamic stability of the alloy was investigated by calculating the critical temperature for SrS1−xSex alloy

Ab initio calculations of the structural, electronic, thermodynamic and thermal properties of BaSe1-xTex alloys

The alkaline earth metal chalcogenides are being intensively investigated because of their advanced technological applications, for example in photoluminescent devices. In this study, the structural, electronic, thermodynamic and thermal properties of the BaSe1?x Te x alloys at alloying composition x?=?0, 0.25, 0.50, 0.75 and 1 are investigated. The full potential linearized augmented plane wave plus local orbital method designed within the density functional theory was used to perform the total energy calculations. In this research work the effect of the composition on the results of the parameters and bulk modulus as well as on the band gap energy is analyzed. From our results, we found a deviation of the obtained results for the lattice constants from Vegard's law as well as a deviation of the value of the bulk modulus from the linear concentration dependence. We also carried out a microscopic analysis of the origin of the band gap energy bowing parameter. Furthermore, the thermodynamic stability of the considered alloys was explored through the measurement of the miscibility critical temperature. The quasi-harmonic Debye model, as implemented in the Gibbs code, was used to predict the thermal properties of the BaSe1?x Te x alloys, and these investigations comprise our first theoretical predictions concerning the BaSe1?x Te x alloys

Ab initio calculations of the structural, electronic, thermodynamic and thermal properties of BaSe1-xTe x alloys

The alkaline earth metal chalcogenides are being intensively investigated because of their advanced technological applications, for example in photoluminescent devices. In this study, the structural, electronic, thermodynamic and thermal properties of the BaSe1-xTe x alloys at alloying composition x = 0, 0.25, 0.50, 0.75 and 1 are investigated. The full potential linearized augmented plane wave plus local orbital method designed within the density functional theory was used to perform the total energy calculations. In this research work the effect of the composition on the results of the parameters and bulk modulus as well as on the band gap energy is analyzed. From our results, we found a deviation of the obtained results for the lattice constants from Vegard's law as well as a deviation of the value of the bulk modulus from the linear concentration dependence. We also carried out a microscopic analysis of the origin of the band gap energy bowing parameter. Furthermore, the thermodynamic stability of the considered alloys was explored through the measurement of the miscibility critical temperature. The quasi-harmonic Debye model, as implemented in the Gibbs code, was used to predict the thermal properties of the BaSe1-xTe x alloys, and these investigations comprise our first theoretical predictions concerning the BaSe1-xTe x alloys