Elastic properties of MFe3N (M=Ni, Pd, Pt) studied by ab initio calculations

Abstract

Using ab initio calculations, we have studied the correlation between the electronic structure and elastic properties of M Fe3 N phases (M=Ni, Pd, Pt). These ternary nitrides possess a bulk-modulus-to- C44 ratio from 2.3 to 2.9, a rather unusual ratio for nitrides. This may be understood based on the electronic structure: Predominantly covalent-ionic Fe-N layers are interleaved with predominantly metallic Fe-M layers. We propose that the unusually large bulk-modulus-to- C44 ratio is a consequence of weak coupling between the Fe-N and Fe-M layers (giving rise to a low C44) as well as strong coupling within Fe-N layers (giving rise to a large bulk modulus). © 2006 American Institute of Physics.