Conversion of Nano-Sized Spherical Magnetite to Spherical Barium Ferrite Nanoparticles for High Density Particulate Recording Media

We report 24-30 nm spherical barium ferrite (S-BaFe) particles having extremely narrow size distribution without any superparamagnetic phase. We have converted spherical magnetite (S-Mag) nanoparticles to S-BaFe nanoparticles using a unique adsorption-diffusion process. The synthesized S-BaFe nanoparticles were characterized by X-ray diffractometer, Mossbauer spectrometer, transmission electron microscope (TEM), and vibrating magnetometer (VSM) for magnetic and physical properties. Saturation magnetization and coercivity of the S-BaFe nanoparticles were found to be 41.4 emu/g and 4075 Oe, respectively. The thermal stability of K
_u
V/k
_B
T ap 107 was estimated for the S-BaFe nanoparticles from time-dependent remanent coercivity measurement.