Study Of Physical Nature Of Fe₁₆N₂

Fe16N2compounds have potential practical value due to its high magnetization, low coercive force, high magnetic permeability, wear-resisting and high economic value, etc. In our work, we are trying to study the preparation technology through the experiment and research the changes when we doped transition metal into Fe16N2structure by using the first-principle calculation method.This article is mainly divided into two parts:experiment and theoretical calculation.1) In experimental section, firstly, we prepared Fe3O4nano-particles with co-precipitation method, and then nitrided in NH3atmosphere to abtain Fe-N compound. We studied the factors that may affect the size of Fe3O4and successfully prepared Fe3O4magnetic nano-particles which size is less than10nanometers. After that, the precursor was nitrided in NH3atmosphere after reduction in H2atmosphere for few hours. We have researched two important factors that may affect the final product:nitriding temperature and nitriding time. It is pity that our experiment fails in the end because Fe16N2can be easily oxidized in the air and our laboratory cannot afford the protect condition yet. But what I did laid a good foundation for the further experiment preparation.2) Theoretical calculation work mainly adopts the first-principle theory based on a full-potential Linearized Augmented Plane Wave method for the calculation of electronic structure. We studied some physical properties including the electronic structure, Fe-N distance and magnetic moment, etc. Otherwise, we research the influence when Mn, Co, Ni is doped into Fe16N2.Our calculation obtains that the average magnetic moment of Fe16N2is2.43μb, Felll atom’s magnetic moment is bigger than that of Fe I atom and Fe Ⅱ atom. After doping Mn, Co, Ni atom, the Fe-N distance and total hyperfine field become smaller. In doping structure, the average magnetic moment of three kinds of Fe atom is decrease, so is the total magnetic moment. Releatively speaking, Mn doping structure is the most stable case and Ni doping structure is the worst case.