Magnetic and Optical Properties of Mn sub(1-x)Zn sub(x)Fe sub(2)O sub(4) Nanoparticles

Mn sub(1-x)Zn sub(x)Fe sub(2)O sub(4) (x = 0.0-1.0) NPs (MZF NPs) were synthesized by a citric acid assisted sol-gel process. MZF NPs show superparamagnetic characteristics at room temperature. Saturation magnetization (M sub(s)) of MnFe sub(2)O sub(4) NPs is 70.52 emu/g is very close to the bulk saturation magnetization value of 80 emu/g. The observed M sub(s) = 35.90 emu/g value for ZnFe sub(2)O sub(4) particles is much greater than the bulk M sub(s) value of 5 emu/g. This case is attributed to cation distribution change from normal spinel to mixed structure. The small M sub(r)/M sub(s) ratios (the maximum 0.147) specify uniaxial anisotropy in the Mn sub(1-x)Zn sub(x)Fe sub(2)O sub(4) NPs. The average crystallite diameter (D sub(mag) )was evaluated from magnetic analyses. The obtained D sub(mag )values are between 27.67 and 33.60 nm and this range is in great accordance with the results calculated from XRD measurements. Among the NPs, the samples with more zinc content show higher diffuse reflectance. The optical direct band gap of MZF NPs is found to decrease from 2.1 to 1.90 eV as the zinc content rises.