On the reaction kinetics of nickel ferrite from iron and nickel oxides

Nickel ferrite, NiFe2O4, is usually obtained by the ceramic method from a stoichiometric mixture of the corresponding oxides, NiO and Fe2O3, finely powdered. In this paper, an investigation of the kinetics of this reaction at temperatures in the range 850–1000 °C and times, t, 1 to 64 min, for powders with a 200 mesh particle size, is presented. Transformed fraction, α, was determined by measuring the area ratio under (220) NiFe2O4 and (104) α-Fe2O3, x-rays diffraction peaks, and interpolating this ratio with a calibration curve constructed with carefully prepared mixtures of these oxides. A study of statistics showed that this can be considered as a non-autocatalytic, deceleratory reaction, obeying an expression of the type α = Btn, where B and n are temperature-dependent. A correlation coefficient R2 = 0.995 was observed. A comparison is made with results obtained by measuring peak heights instead of peak areas, which shows a slightly lower correlation coefficient.