Magneto Optical Properties of FeBxFe2-xO4 Nanoparticles

In this study, FeBxFe2-xO4 nanoparticles (NPs) were synthesized by the polyol method. The M-H hysteresis curves exhibit superparamagnetic characteristics that are both coercivity and remanent magnetization values are negligible. The particle size dependent Langevin function was applied to calculate the magnetic particle dimensions around 9 nm. The measured magnetic moments of NPs are in range of (1.52-2.2) A mu(B) and almost half or less with respect to 4 A mu(B) of bulk Fe ferrite. Magnetic anisotropy was specified as uniaxial and calculated effective anisotropy constants (K (eff) ) are between 43.3 x 10(4) and 19.4 x 10(4) emu/g. The UV-Vis diffuse reflectance spectroscopy and Kubelka-Munk theory were used to determine the optical properties. The estimated optical band gap values (2.15-2.48 eV) of FeBxFe2-xO4 NPs are bigger with respect to reported values (1.88-2.12 eV) for Fe3O4 NPs in the literature. The bigger E (g) values are mainly attributed to B concentration and partly to quantum confinement effect.