Abstract
Citric, oxalic and tartaric acids were used for synthesis of NiFe2O4 using polymeric complex precursor route. The dry precursor gels were calcined at various temperatures (400-1100 degrees C) for 2 h. All carboxylic acids produce iron-deficient NiFe2O4 with considerable amount of alpha-Fe2O3 at 400 degrees C. increase in the annealing temperature caused reaction of alpha-Fe2O3 with iron-deficient ferrite phase. The amount of initially formed alpha-Fe2O3 is directly correlated with stability constant and inversely correlated with the decomposition temperature of Fe(III) carboxylate precursors. In case of tartaric acid precursor, single phase of the ferrite was obtained at 450 degrees C. However, in case of oxalic acid and citric acid precursors, single phase ferrite was obtained at 550 degrees C and 700 degrees C, respectively. The lattice parameters were increased with increasing annealing temperature and with decreasing the amount of alpha-Fe2O3. Maximum saturation magnetization (55 emu/g) was achieved using tartaric acid precursor annealed at 1100 degrees C. (C) 2015 Elsevier B.V. All rights reserved.