Elastic and magnetic properties of cubic Fe$_{4}$C from first-principles
Abstract
First-principles based on density functional theory is used to study the phase stability, elastic, magnetic, and electronic properties of cubic (c)-FeC. Our results show that c-FeC has a ferromagnetic (FM) ground state structure compared with antiferromagnetic (AFM) and nonmagnetic (NM)states. To study the phase stability of c-FeC, BCC FeC, FCC FeC, and BCC FeC, where C is considered at tetrahedral and octahedral interstitial sites, are also considered. Although, the formation energy of c-FeC is smaller than BCC FeC, but the shear moduli of c-FeC is negative in the FM and AFM states indicating that c-FeC is dynamically not stable in the magnetic (FM/AFM) states. However, NM state has positive shear moduli which illustrates that instability in c-FeC is due to magnetism and can lead to soft phonon modes. The calculated formation energy also shows that c-FeC has higher formation energy compared with the FCC FeC indicating no possibility of c-FeC in low carbon steels at low temperature. The magnetic moment of Fe in c-FeC is also sensitive to lattice deformation. The electronic structure reveals the itinerant nature of electrons responsible for metallic behavior of c-FeC.
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@article{arxiv.1408.5489,
title = {Elastic and magnetic properties of cubic Fe$_{4}$C from first-principles},
author = {Gul Rahman and Haseen Ullah Jan},
journal= {arXiv preprint arXiv:1408.5489},
year = {2014}
}
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