2024年11月22日，Elsevier 旗下top期刊《Ceramics International》在线发表了云南师范大学物理与电子信息学院王洪恩教授团队的最新研究成果《First-Principles Investigation of the Structural, Electronic, and Thermodynamic Properties of M3AC2 MAX Phases under Varying Temperature and Pressure》。云南师范大学物理与电子信息学院王洪恩教授为通讯作者。
https://www.sciencedirect.com/science/article/pii/S0272884224054440
Abstract
This study employs first-principles (DFT) simulations to investigate the structural, electronic, and thermodynamic properties of hexagonal M3AC2 (M = Ti, V; A = Al, Si) MAX phases. The structural stability of these materials was assessed by calculating their cohesive and formation energies. Among the compounds studied, Ti3SiC2 displayed the most negative cohesive energy of -2.18 eV/atom, indicating superior stability compared to Ti3AlC2 and V3AlC2. This high stability is attributed to robust metallic bonding in titanium. The thermodynamic properties of the M3AlC2 MAX phases were further analyzed under various temperatures and pressures using the quasi-harmonic Debye approximation. This approach enabled an exploration of temperature and pressure effects on several key properties, including heat capacity (Cv and Cp), bulk modulus, thermal expansion coefficient, Debye temperature, enthalpy, entropy, and Gibbs free energy. Results showed that the bulk modulus decreases with increasing temperature, but increases with pressure, while the Debye temperature exhibits an inverse trend. Heat capacities (Cv and Cp) rise with temperature due to increased atomic thermal velocity. In contrast, higher pressure reduces atomic thermal velocity, causing an opposing effect on heat capacities. Furthermore, the slope of the Gibbs free energy shows a slight increase under constant pressure. These findings, indicating enhanced thermodynamic properties, suggest that M3AC2 MAX phases, particularly Ti3SiC2, could be promising for applications requiring resistance to high-temperature fatigue, especially in a gas turbine engine.
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