Elastic anisotropy and thermodynamic properties of chromium tetraboride from first‐principles calculations

First‐principles calculations are performed to investigate the elastic anisotropy, and thermodynamic properties of chromium tetraboride (CrB 4 ) under extreme P – T conditions. The calculated equilibrium lattice and the normalized crystal parameters as a function of pressure are in good agreement with the available experimental and theoretical data. Elastic constants C ij are calculated in the pressure range of 0–50 GPa, and the bulk modulus B , shear modulus G , and Young's modulus E are also obtained according to the Voigt–Reuss–Hill (VRH) approximation. Anisotropic indexes are employed to characterize the mechanical anisotropy. The bulk modulus and Young's modulus as a function of crystal orientations are also investigated. The obtained results suggest that CrB 4 exhibits a pronounced elastic anisotropy. It is strongest along the b ‐axis in response to compression loading, and the {100} and {001} shear planes might be the cleavage planes. The elastic anisotropy of CrB 4 may possibly limit its applications. Using the quasiharmonic Debye model, thermodynamic properties like Debye temperature, Grüneisen parameter, heat capacity, and expansion coefficient are also systematically explored under extreme P – T conditions.