Unveiling the Multifunctional Behavior of NaXTe2 (X = Al, Ga, In) Ternary Tellurides: A First-Principles Perspective

M. Elbaaa, S. Hairecheb, A. Khelefhoumc, d, S. Maabedd, M. Bouchenafad aLaboratory of Energy and Intelligent Systems, Faculty of Matter Sciences and Computer Science, University of Khemis Miliana, 44225, Algeria bLaboratory of Mechanics, Physics, and Mathematical Modelling, University of Medea, Medea 26000, Algeria cUniversity of Science and Technology Houari Boumediene, Faculty of Electrical Engineering, Automatic Department, BP.32, El-Alia, Bab Ezzouar, 16111 Algiers, Algeria dLaboratoire de Matériaux pour Application et Valorisation des Energies Renouvelable (LMAVER), Département de Sciences de la Matière, Université Amar Telidji Laghouat, BP 3000, Algeria

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This work presents a novel and in-depth first-principles investigation of the ternary telluride compounds NaXTe2 (X = Al, Ga, In) with the aim to systematically uncover their structural, electronic, elastic, and optical characteristics. Using density functional theory calculations, we report for the first time, within a unified framework, a comparative analysis of these compounds crystallizing in the tetragonal I4/mcm space group. Structural optimization yields lattice parameters in excellent agreement with experimental data, confirming the validity of the computational approach. A key finding of this study is the identification of direct band gaps at the Z point for all the investigated compounds, with significantly different values (1.28 eV for NaAlTe2, 0.23 eV for NaGaTe2, and 0.58 eV for NaInTe2), which have not been consistently reported in the literature. The projected density of states reveals pronounced hybridization between the X and Te orbitals, shedding new light on the nature of covalent bonding in the lattice. From a mechanical standpoint, the full elastic tensor, including directional-dependent moduli, demonstrates the mechanical stability and ductility of these compounds, while also quantifying their moderate hardness - a desirable feature for practical integration in devices. Notably, optical analyses reveal a strong absorption in the ultraviolet range, accompanied by favorable dielectric responses and refractive indices, indicating high potential for these materials in ultraviolet-optoelectronic and photovoltaic applications. Overall, this study introduces new insights into the multifunctional behavior of NaXTe2 compounds, establishes a reference dataset for future experimental validation, and highlights these materials as promising candidates for the development of next-generation semiconductors and optical devices.

DOI:10.12693/APhysPolA.149.78 topics: telluride materials, density functional theory (DFT), condensed matter, band gap