Isothermal reduction kinetics at 900-1100 °C of NiFe2O4 sintered at 1000-1200 °C

The characteristic of the prepared nickel ferrite have been studied using X-ray diffraction analysis technique, reflected light microscope and porosity measurements. The behavior of nickel ferrite in hydrogen atmosphere at 900-1100 °C has been studied using thermogravimetric techniques. The reduction of NiFe2O4 is not found to proceed to completion at any firing or reduction temperature. The reduction proceeds via a topochemical mode. At firing temperatures 1000 and 1100 °C, the rate is controlled initially by the combined gaseous diffusion interfacial chemical reaction mechanism while at the final stages, the interfacial chemical reaction is predominantly the rate-controlling mechanism. At 1200 °C, initially the rate controlling is the interfacial chemical reaction mechanism while the solid-state diffusion is rate-controlling mechanisms at the final stages.