Modulation on Structural Stability and Magnetic Properties of RFe12 (R = Rare Earth) by Substitution of Mo or V for Fe at the 8i Crystal Position

Abstract

In this study, empirical electron theory is used to investigate the valence electron structures and magnetic properties of RFe₁₀T₂ (R = rare earth; T = Mo or V) intermetallic compounds for revealing the mechanisms of their structural stabilities and magnetic properties. The calculated bond length and magnetic moment as well as the Curie temperature are in agreement with the observed ones, and the cohesive energy and melting point match the experimentally evaluated ones. It is suggested that structural stability and magnetic moment are strongly related to the valence electron structures of Fe atoms modulated by Mo or V at the 8i crystal position. The increase of the covalence electron number is helpful for enhancing the structural stability. The melting point and cohesive energy are positively related to the maximum number of covalence electron pairs n_α^M on the strongest bond and covalence electrons n_c/atom, respectively. Curie temperature depends on the numbers of 3d magnetic electrons of Fe sublattices and 4f moments of rare earths. However, the effect of nitrogen absorption can cause the electron transformation from a covalence electron to a magnetic electron in the Fe atom, which induces the increases of moment and Curie temperature. The bonding interaction is enhanced by introducing a valence electron of nitrogen.