Structural and magnetic properties of nanometric Zn-ferrite prepared by different methods

This work has the objective of studying the influence of preparation methods on the structural, morphology and magnetic properties of ZnFe2O4 ferrites. The samples were prepared by various methods of synthesis (conventional ceramic method, sol-gel, freeze-drying and hydrothermal method), and were characterized by X-ray diffraction (XRD), (SEM) and (TEM) micrographs and magnetization measurements. The characteristics of ZnFe2O4 sample prepared by different methods have been studied to select the better method, i.e. the one that is the simplest and does not require an elaborate instrumental set-up. The results indicated that the hydrothermal method gives the lowest value for the lattice parameter (8.4261 angstrom) and small nanosizes of particles (14 nm), while the highest values (a=8.4394 angstrom and d=158.5 nm) are obtained with the ceramic method. The DC magnetization (2-300 K) measurements reveal a superparamagnetic behaviour for this sample prepared by hydrothermal method with a blocking temperature (T-B=12K). In the case the ceramic method T-B equal to 20K. Over the TB all the samples ZnFe2O4 show a paramagnetic behavior.