First-principles study of elastic and thermodynamic properties of orthorhombic OsB4 under high pressure

The first-principles study on the elastic properties, elastic anisotropy and thermodynamic properties of the orthorhombic OsB4 is reported using density functional theory method with the ultrasoft pseudopotential scheme in the frame of the generalized gradient approximation. The calculated equilibrium parameters are in good agreement with the available theoretical data. A complete elastic tensor and crystal anisotropies of the ultra-incompressible OsB4 are determined in the pressure range of 0–50 GPa. By the elastic stability criteria, it is predicted that the orthorhombic OsB4 is stable below 50 GPa. By using the quasi-harmonic Debye model, the heat capacity, the coefficient of thermal expansion, and the Grüneisen parameter of OsB4 are also successfully obtained in the present work.

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► The elastic and thermodynamic properties of OsB4 under pressure were studied unified.
► It is predicted that the orthorhombic OsB4 is stable below 50 GPa
► The orthorhombic OsB4 exhibits larger elastic anisotropy under higher pressure.
► The thermodynamic parameters are also successfully obtained by the Debye model.