Synthesis of Nanocrystalline Nickel-Zinc Ferrites via a Microemulsion Route

Abstract

Nanostructured NiZn-ferrites were synthesized using a low-temperature co-precipitation method within the reverse micelles of ternary CTAB/1-hexanol/water microemulsions. The influence of pH on the precipitation reaction was investigated. It was found that a higher pH resulted in more crystalline particles. Subsequent oxidation of the ferrous ions and their precipitation, which leads to the formation of spinel ferrites, is discussed. Diffraction-lines broadening and specific surface area measurements revealed an average particle size of ~ 3 nm. The saturation magnetization of the samples was 20 times smaller than for traditionally synthesized NiZn-ferrites, while the coercivities were 10 - 100 times larger than for bulk NiZn-ferrites, which is consistent with the nanocrystalline nature of the synthesized magnetic material. TEM investigations were used to show the agglomerated nature of the synthesized samples, which is the reason why the samples do not show superparamagnetic behavior.