Statistico-Thermodynamical Studies on the Fundamental Reactions concerning Steel-Making. IV : The Oxidation and Reduction Equilibrium of Magnetite with Gas Phases

概要

論文の詳細を見る
It is known that magnetite crystals can contain excess oxygen over the stoichiometric composition of Fe_3O_4 by high temperature oxidation, and the oxygen content depends on the oxygen pressure in atmosphere and on the temperature. The Fe_3O_4 crystal has a crystal structure of the inversed-spinel type, in which O^<--> ions occupy the closed packed cubic lattice points, and the tetrahedral lattice sites (8 f) of its unit cell are occupied by 8 Fe^<+++> ions, and octahedral lattice sites (16 c) by 8 Fe^<+++> and 8 Fe^<++> ions statistically. When the magnetite crystal contains excess oxygen under an oxidizing atmosphere, it can be assumed that a vacant site accompanying two electron defects which result in two Fe^<+++> ions is found on the octahedral lattice points occupied by Fe^<++> ions. Under these circumstances we can calculate the partition function of magnetite phase, from which the equilibrium relation between the oxygen content in magnetite, the partial pressure of oxygen in atmosphere and the temperature is deduced theoretically. These results are in good agreement with observations by Greig et al. and Darken and Gurry.
東北大学の論文