Role of Si concentration on the thermodynamic properties of molybdenum silicides

Abstract Thermal stability of high-temperature materials plays an important role for high-temperature application. Although molybdenum silicides(Mo-Si) are promising ultrahigh-temperature materials, the thermodynamic properties of Mo-based silicides are unknown. In this letter, we apply the first-principles calculations to investigate the influence of Si concentration on thermodynamic properties of Mo-based silicides. We find that the Debye temperature and heat capacity of Mo-based silicides depend on the Si concentration. The Debye temperature of Mo-based silicides increases with increasing Si concentration. The calculated Debye temperature of MoSi 2 is 576 K. The reason is attributed to the vibration of Si atom and Si-Si covalent bonds.