Investigation of nickel ferrite formation in a binary Fe(III)-Ni(II) hydroxide precipitate containing H_2O with or without Li_2O doping

摘要

The effects of calcination time, calcination temperature, particle size of the precursor precipitate, and Li_2O doping on interactions within a mixed Fe(III)-Ni(II) hydroxide precipitate were investigated using thermogravimetry (TG), differential thermal analysis (DTA), and X-ray diffraction (XRD). The results indicated that neither the reaction time nor the particle size influenced the formation of nickel ferrite. It was found that the Fe(III) hydroxides participated in solid-solid interactions with the Ni(II) hydroxides to yield nickel ferrite at temperatures above 290 deg C. Increasing the percentage of Li_2O dopant reduced the rate of nickel ferrite formation but increased that of nickel oxide formation, regardless of the calcination temperature between 400 and 700 deg C. These phenomena may be ascribed to the inhibition of crystallization of alpha-Fe_2O_3 by the substitution of some Li~+ ions into Fe_2O_3 lattice structure.