A semiconductive superhard FeB4 phase from first-principles calculations

Abstract

An oP10–FeB₄ phase [H. Gou, et al., Phys. Rev. Lett., 2013, 111, 157002] was recently synthesized based on previous theoretical predictions. In this study, a high-pressure phase of FeB₄ (tP10–FeB₄) was proposed through first-principles calculations. The tP10–FeB₄ structure, which contains two formula units per unit cell, belongs to tetragonal symmetry with the space group P4₂/nmc. The boron atoms in tP10–FeB₄ are present as tetrahedron configurations. Enthalpies as a function of pressure indicate that this new phase is probable to achieve through a phase transition from the oP10–FeB₄ phase above ∼65.9 GPa. The softening of acoustic phonon at T points in the Brillouin zone may be the driving force behind the phase transition. Further analyses reveal that the tP10–FeB₄ phase is a potential superhard semiconductor.