Hollow Nanostructured Ni₃Fe Microspheres Obtained by Spray Pyrolysis

A study of a two-stage method for the formation of nanostructured Ni₃Fe is presented. Nanostructured Ni₃Fe hollow microspheres were synthesized by ultrasonic spray pyrolysis (URP) from a mixture of aqueous solutions (10 wt.%) of nickel(II) and iron(III) nitrates. In the first stage, hollow microspheres with diameters in the range 0.5 – 10 μm were formed from a mixture of Ni and Fe oxides. The second stage involved metallization of a mixture of Ni and Fe oxides in a tube furnace in a hydrogen atmosphere. X-ray diffraction (XRD) data of the final product showed the presence of the Ni₃Al phase and a crystallite size close to 40 nm. Scanning and transmission electron microscopy revealed the hollow morphology of the studied Ni₃Fe microspheres. Their walls were assembled from crystallites with diameters of 30 – 60 nm.