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February 11, 2026International Journal of Modern Physics B0 citations

Tailoring the structural stability, lattice parameters, phase transition, electronic, optical, mechanical, and thermoelectric preferences of AlAs1−xBix alloys: A DFT study

WGW. Gouasmia DBDjamel Boudjaadar FOF. Oumelaz

Key Points

The aim is to investigate the structural, electronic, optical, mechanical, and thermoelectric properties of AlAs1−xBix alloys using density functional theory (DFT).
Utilized the full-potential linearized augmented plane wave (FP-LAPW) method within DFT.
Applied Wu–Cohen Generalized Gradient approximation (WC-GGA) for structural stability analysis.
Evaluated electronic properties using KTB-mBJ and EV-GGA approaches.
Conducted optical, mechanical, and thermoelectric performance assessments.
Lattice constants increased from 5.679 Å to 6.359 Å with Bi concentration.
Bulk modulus decreased from 71.94 GPa to 43.39 GPa as Bi increased.
Band gap transitioned from indirect to direct with increasing Bi, ranging from 2.145 eV to 0.325 eV.
Optical properties showed redshift in absorption edges, suitable for infrared applications.
ZT values indicated promising thermoelectric performance, with maximum value of 0.77 for composition 0.

Abstract

This study employs the full-potential linearized augmented plane wave (FP-LAPW) method within the density functional theory (DFT), as implemented in the WIEN2k code, to investigate the structural, electronic, optical, mechanical, and thermoelectric properties of AlAsFormula: see textBi x alloys for Formula: see text, 0.25, 0.5, 0.75, and 1. Using the Wu–Cohen Generalized Gradient approximation (WC-GGA), the studied alloys were found to be structurally stable in the zinc-blende phase. The lattice constants exhibited a progressive increase from 5.679Formula: see textÅ to 6.359Formula: see textÅ with increasing Bi concentration, while the bulk moduli decreased correspondingly from 71.94Formula: see textGPa to 43.39Formula: see textGPa. Investigation of electronic properties using both the KTB-mBJ Formula: see text PBE and EV-GGA approaches revealed a transition from an indirect band gap at Formula: see text to direct band gaps at higher Bi concentrations, accompanied by a systematic reduction in band gap values. In particular, the band gaps calculated using the KTB-mBJ scheme were found to be 2.145, 1.919, 1.415, 0.842, and 0.325Formula: see texteV for compositions Formula: see text, 0.25, 0.5, 0.75, and 1, respectively. The optical analyses results demonstrated a redshift in the absorption edges of the alloys, indicative of their potential applicability in infrared and optoelectronic devices. Mechanical investigations confirmed that the alloys are brittle, anisotropic, and predominantly covalent in nature, with observed reductions in stiffness and hardness as Bi concentration increases. Thermoelectric performance evaluations further showed enhanced power factor values and diminished thermal conductivity with the addition of Bi. The obtained figure of merit (ZT) values for the investigated compositions were 0.77, 0.67, 0.70, 0.65, and 0.76 for Formula: see text, 0.25, 0.5, 0.75, and 1, respectively. These findings highlight the promising potential of the studied ternary alloys for use in thermoelectric technologies due to their advantageous performance indices.

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