Phase stability, electronic structure and equation of state of cubic TcN from first-principles calculations

• The phase transition pressure and electronic band structure for cubic TcN are determined.
• Particular attention is paid to investigate the equation of state parameters for cubic TcN.
• The thermodynamic properties up to 80 GPa and 3000 K are successfully predicted.

The phase transition, electronic band structure, and equation of state (EOS) of cubic TcN are investigated by first-principles pseudopotential method based on density-functional theory. The calculated enthalpies show that TcN has a transformation between zincblende and rocksalt phases and the pressure determined by the relative enthalpy is 32 GPa. The calculated band structure indicates the metallic feature and it might make cubic TcN a better candidate for hard materials. Particular attention is paid to the predictions of volume, bulk modulus and its pressure derivative which play a central role in the formulation of approximate EOSs using the quasi-harmonic Debye model.