Abstract
Nano-crystalline Mn-Zn ferrite powders (Mn1-xZnxFe2O4, x=0∼1.0) have been prepared by ultrasonic spray pyrolysis method. Mn-Zn ferrite samples sintered at 700°C had the single phase of spinel-type for all of the compositions. The lattice constant decreased with increasing Zn content and followed Vegard's law. Curie temperature linearly decreased from that of MnFe2O4 (x=0) with increasing Zn substitution rate. These results indicate that the Mn-Zn ferrite formed solid solution. The Mn-Zn ferrite particles were found to be in nano-size of 20∼30 nm by scanning electron microscopy. And their crystalline diameters were 15∼30 nm, determined by the use of Scherrer equation for X-ray diffraction peak broadening. Mn0.6Zn0.4Fe2O4 sample had a magnetization value of 48 emu/g, which was lower than that of bulk sample (80 emu/g). This is possibly caused by the existence of a disordered surface region on the nanoparticles, where the crystallographic and magnetic structures are disordered due to the nearly random distribution of cations and the canted spin arrangement.
