The dispersed nanocrystallite particles of ZnFe2O4 have been synthesized by sol-gel auto-combustion with the aid of ultrasonic irradiation methods using different fuel additives of glycine, urea and thiourea. The ratios of fuel- to- nitrates were maintained variously at 1.2 : 1, 2 : 1, and 3 : 1. The results revealed that, the difference in the phase composition formed are mainly attributed to the combustion process. In turn, different fuel additives exert a direct influence in the combustion reaction on the formation of a homogeneous gel, the formation of a good complex with metal cations and release chemical energy; as well as, showed that, the crystallite size of Zn ferrite powders is affected by the compositional ratios of fuel–to-nitrates. High fuel/ oxidant ratios increase the particle size and may enhance dopant segregation. The studies on the composition of phases, crystallite sizes, and morphology of the powder ferrite formed were investigated by X-Ray diffraction (XRD) and scanning electron microscopy (SEM), respectively. The results demonstrated that, the average crystal sizes distribution obtained were in the range 11-38 nm for all compositions.

Keywords: Auto combustion, Ultrasonic, Nanocrystallite particles, Zn ferrite, Fuel additives.