Deformation-induced bonding evolution of iron tetraboride and its electronic origin

First-principles density functional calculations are employed to provide a fundamental understanding of the structural features, mechanical properties, deformation behaviours and its electronic origin for the new synthesized FeB4. The calculated elastic moduli suggest that FeB4 has a low compressibility, but results of ideal shear strength and theoretical hardness indicate that FeB4 is a hard material, not a superhard material. We find that the collapse of the unique corrugated B-6 units ring in FeB4 under deformation is responsible for the failure under tensile and shear deformation based on the calculated charge density distribution and bonding evolution. ((c) 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)