Synthesis and characterization of pure single phase Ni–Zn ferrite nanopowders by oxalate based precursor method

Series of single-phase Ni 1 − x Zn x Fe 2O 4 ( x = 0.20, 0.35, 0.50 and 0.60) nanopowders with average particle size of ∼ 35 nm have been synthesized by using oxalate based precursor method. Precursor powders were synthesized by reacting aqueous solutions of metal nitrates and oxalic acid by using different total metal ions: oxalic acid molar ratios and then evaporating them to dryness. Pure, single-phase Ni–Zn ferrite nanopowder was formed by calcining the precursor with total metal ion: oxalic acid ratio of 1:0.125 at a temperature of 850 °C. The synthesized nanopowders were characterized by using X-ray diffraction, Thermo-gravimetric and Differential Scanning Calorimetric analysis, Transmission Electron Microscope and Scanning Electron Microscope. Room temperature DC resistivity of the nanopowders was measured with respect to temperature by the two-probe method and was of the order of ∼ 10 7 Ωcm. Room temperature saturation magnetization was measured by using Vibrating Sample Magnetometer and it varied between 34–49 emu/g depending on the composition. This aqueous solution based method provides a simple and cost-effective route to synthesize single phase, Ni–Zn ferrite nanopowders. An oxalate based precursor method has been developed in which the total metal ions: oxalic acid ratio has been optmised in order to synthesize pure Ni–Zn ferrite nanopowders in pure aqueous medium. XRD spectra of the powders confirmed the formation of single-phase Ni–Zn ferrite phase when the molar ratio between total metal ions and oxalic acid was 1:0.125. TEM micrographs revealed that the particles were spherical in shape with average particle size of ∼ 35 nm. ▪