Kinetics of Nickel Ferrite Formation

Abstract

The rate of nickel ferrite formation is influenced by the milling technique and in the case of wet milling by the type of liquid media used. The reactivity of different types of α-Fe₂O₃ of spherical shape decreases with an increase of the surface area ratio of α-Fe₂O₃ to NiO. The particle shape of the iron oxides also affects their reactivity; cubical α-Fe₂O₃ has the least reactivity in the formation of nickel ferrite. The validity of Jander's equation in ferrite formation is reviewed. Based on present findings the rate of ferrite formation is best represented by the equation dx/dt= (a-x)/t, in which x is the percentage of ferrite formed, t the time, and a the kinetic isothermal reaction rate coefficient which is related to the surface area ratio of the reacting oxides. The application of the foregoing equation to the formation of magnesium ferrites from data found in the literature is also satisfactory.