Electrical conductivity variation during solid synthetic process of NiFe2O4-NiO

摘要

For the purpose of investigating the effect of additive MnO2 and TiO2 on the synthetic reaction of NiFe2O4-NiO, a new method of monitoring the electrical conductivity of samples during the solid synthetic process was utilized. NiFe2O4-NiO was synthesized from the mixed powder of NiO and Fe2O3 with the additions of l%MnO2 and 0.5%TiO2 at 11731233 K and was characterized by scanning electron microscopy (SEM). The electrical conductivity of the samples was recorded during the synthetic process and was used to study the synthetic kinetics of NiFe2O4NiO. The synthetic reaction of NiFe2O4-NiO was of diffusion-control and followed the first order kinetics equation. The rate coefficients and the activation energies of the synthetic reaction of NiFe2O4-NiO as well as the average diffusion coefficients of Ni2+ and Fe3+ wers estimated within the temperature range of 1173-1233 K. Both the additions of l%MnO2 and 0.5%TiO2 increased the electrical conductivity of the NiFe2O4-NiO and improved the surface microstructure and speeded the synthetic reaction.