Modeling the thermal stability and thermodynamic properties of tetragonal monochalcogenide TlSe at high temperature and pressure

• Published in: Indian journal of physics Vol. 99; no. 8; pp. 2831 - 2842
• Main Authors: Bencheikh, Mounaim, El Farh, Larbi
• Format: Journal Article
• Language: English
• Published: New Delhi Springer India 01.07.2025; Springer Nature B.V
• Subjects: Anharmonicity; Astrophysics and Astroparticles; Bulk modulus; Debye temperature; Density functional theory; Entropy; Gibbs free energy; Gruneisen parameter; High temperature; Low temperature; Melt temperature; Original Paper; Physics; Physics and Astronomy; Plane waves; Pressure effects; Specific heat; Temperature; Thallium; Thermal conductivity; Thermal expansion; Thermal stability; Thermodynamic properties; Thermodynamics; Quasi-harmonic debye model; DFT; Monochalcogenide TlSe; Wien2k; FP-LAPW; Thermodynamic properties; Thermal stability; Gibbs 2 code
• ISSN: 0973-1458; 0974-9845
• DOI: 10.1007/s12648-024-03519-3

In this research, we employed the Full Potential Linearized Augmented Plane Wave (FP-LAPW) method, implemented within the density functional theory (DFT)-based Wien2k computational framework, to investigate the thermal stability, pressure effects on the band structure and thermodynamic properties of the monochalcogenide semiconductor thallium-selenium (TlSe). Using the quasi-harmonic Debye model and the Gibbs 2 algorithm, we analyzed the effects of pressures ranging from 0 to 25 GPa and temperatures from 0 to 600 K. The bulk modulus is 36.5 GPa at zero temperature and pressure, which aligns with the values reported in the literature. It decreases slightly with increasing temperature but rises significantly under higher pressure. The Grüneisen parameter increases with temperature, indicating greater anharmonicity, while it decreases with pressure, reflecting reduced anharmonicity under compression. The specific heat capacity ( C V ) follows a T 3 behavior at low temperatures and approaches the Dulong-Petit limit ( C V = 199.536 J . mol - 1 . K - 1 ) at higher temperatures. The calculated melting temperature ( T m ≈ 654 K) closely matches the experimental value of 615 K. As the temperature rises, thermal agitation intensifies, leading to an increase in the thermal expansion coefficient. Additionally, entropy increases with temperature, revealing new atomic configurations. Gibbs free energy decreases with increasing temperature, influenced by changes in the compound's thermodynamic properties, such as thermal conductivity. This study reveals a decrease in volume, constant-volume heat capacity, thermal expansion coefficient, Grüneisen parameter, and entropy with increasing pressure. In contrast, the bulk modulus, Debye temperature, and Gibbs free energy increase as pressure rises.