Electronic structure and doping effect of kink in edge dislocation of body-centred cubic iron

Abstract

The self-consistent discrete variational method and the DMol method， based on the density functional theory， are employed to study the electronic structure and the doping effect （N，O） of the kink in the 1/2［111］（110） edge dislocation of body-centred cubic Fe. Our calculations of energies （impurity segregation energy and structural energy） show that N and O each have a strong segregation tendency to enter a kink region， which is related to the lattice distortion introduced by the kink. Furthermore， we find that there exist some charge accumulations between impurity and its neighbouring Fe atoms， resulting in unhomogeneous charge distribution in the kink. N and O atoms obtain electrons while the neighbouring Fe atoms lose electrons. It is found that the interactions between impurity N atom and neighbouring Fe atoms are strengthened due to the strong hybridizations between N-p and Fe-3d4s4p states. The migrations of kink and dislocation motion are impeded by N， which may be beneficial to an increase in strength of material. While the interaction between O and its neighbouring Fe atoms is weaker. The localized effect of impurity-kink complex distinctly affects the electronic structure and properties of the system.