Annealing effect on zinc nanoferrite particles synthesized by spray pyrolysis of polymer precursor

Nanosized zinc ferrite particles, prepared by spray pyrolysis method, were investigated by X-ray diffraction, transmission electron microscopy, energy dispersive spectroscopy, Fe57 Mossbauer spectroscopy, and vibrating sample magnetometer. The cubic crystalline phases were identified in all samples. The lattice parameter (a = 8.446 A) and the average particle size of all the samples were determined. The particle sizes increased as the annealing temperature increased from 250 °C to 550 ° C. The variation in structural parameters and particle size estimated from X-ray diffraction patterns of heat-treated samples suggested that the synthesized sample was in a `metastable state or a compositionally constrained state. The Mossbauer spectra of the annealed samples showed a single doublet, thereby indicating the presence of superparamagnetism. Magnetic studies using vibrating sample magnetometer also conrm the superparamagnetic nature of the material.