FP-LMTO Calculations of Structural and Electronic Properties of Alkaline-Earth Chalcogenides Alloys AY:A = Ca, Sr, Ba; Y = S

Abstract

The structural and the electronic properties of the ternary Sr<sub>x</sub>Ca<sub>1-x</sub>S, Ba<sub>x</sub>Ca<sub>1-x</sub>S and Ba<sub>x</sub>Sr<sub>1-x</sub>S alloys have been calculated using the full-potential linear muffin-tin-orbital (FP-LMTO) method based on density functional theory, within both local density approximation (LDA) and generalized gradient approximation (GGA). The calculated equilibrium lattice constants and bulk modulus are compared with previous results. The concentration dependence of the electronic band structure and the direct and indirect band gaps are investigated. Using the approach of Zunger and co-workers, the microscopic origins of the band gap bowing are investigated also. A reason is found from the comparison of our results with other theoretical calculations

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

“…Considering the general trend that GGA usually overestimates the lattice parameters, our PBE-GGA results for SrS and BaS are in good agreement with the experimental and theoretical values. For the compositions x = 0.25, 0.5 and 0.75, our results are in reasonable agreement with those of Ameri et al [23] using FP-LMTO method. The small differences are related to the parameters used in both methods.…”

“…The last type of deformation, which yields C 11 + 2C 12 + 4C 44 , is a rhombohedral distortion. The calculated PBE-GGA elastic constants for the Ba x Sr 1−x S ternary [20], c [21], d [22], e [23], f [12], g [7], h [11], i [24], j [9], k [25], l [26], m [27], n [8], o [28] alloys are listed in Table 2. The requirement of mechanical stability in a cubic structure leads to the following restrictions on the elastic constants: C 11 − C 12 > 0, C 11 + 2C 12 > 0, C 11 > 0, C 44 > 0 and C 12 < B < C 11 .…”

“…[34], b [35], c [11], d [36], e [23], f [37], g [38], h [39], i [9], j [28], k [9], l [40] To analyze the physical origins of the band gap bowing, we followed the procedure of Bernard and Zunger [42] and decomposed the bowing parameter into three physically distinct contributions:…”

Highly efficient emerging Ag2BaTiSe4 solar cells using a new class of alkaline earth metal-based chalcogenide buffers alternative to CdS

“…Researchers have tried using alternatives such as ZnMgO, ZnS, ZnO, Zn(S,O), and In 2 S 3 where the native point defects, large series resistance, high interface recombination, difficulty in controlling the S-to-O ratio along with secondary phase formation, and the presence of rare earth element (In) are found to be their critical problems respectively 25 – 29 . There are non-toxic and earth-abundant options such as MgS, CaS, SrS, and BaS, which are alkaline earth metal-based chalcogenide semiconductors 30 . These materials have low reflectance, low absorbance, and high transmittance in the visible region, making them ideal buffers for thin-film solar cells.…”