Zinc ferrite nano-crystals were synthesized by a microwave assisted combustion
route with varying the urea to metal nitrates (U/N) molar ratio The process takes only a
few minutes to obtain Zinc ferrite powders. The Effect of U/N ratio on the obtained phases,
particle size, magnetization and structural properties has been investigated. The specimens
were characterized by XRD, Mossbauer and VSM techniques. The sample prepared with ¨
urea/metal nitrate ratio of 1/1 was a poorly crystalline phase with very small crystallite size.
A second phase is also detected in the sample. The crystallite size increases while the second
phase decrease with increasing the urea ratio. The saturation magnetization and coercivity
of the as prepared nano-particles changed with the change of the U/N ratio. The powder with
the highest U/N ratio showed the presence of an unusually high saturation magnetization of
16 emu/g at room temperature. The crystallinity of the as prepared powder was developed by
annealing the samples at 700 ◦C and 900 ◦C. Both the saturation magnetization (Ms) and the
remnant magnetization (Mr) were found to be highly dependent upon the annealing temperature.
Mossbauer studies show magnetic ordering in the powder even at room temperature.