Ab initio predicted elastic and thermodynamic properties of Imm2-BN under high pressure

The structural parameters, elastic constants, thermodynamic properties of Imm2-BN under high pressure were calculated via the density functional theory in combination with quasi-harmonic Debye approach. The results showed that the pressure has the significant effect on the equilibrium lattice parameters, elastic and thermodynamic properties of Imm2-BN. The obtained ground state structural parameters are in good agreement with previous theoretical results. The elastic constants, elastic modulus, and elastic anisotropy were determined in the pressure range of 0-90 GPa. Furthermore, by analyzing the B/G ratio, the brittle/ductile behavior under high pressure is evaluated and the elastic anisotropy of the Imm2-BN up to 90 GPa is studied in detail. Moreover, the pressure and temperature dependence of thermal expansion coefficient, heat capacity, Debye temperature, and Grüneisen parameter are predicted in a wide pressure (0-90 GPa) and temperature (0-1600 K) ranges. The obtained results are expected to provide helpful guidance for the future synthesis and application of Imm2-BN.