Conversion of Worm-Shaped Antiferromagnetic Hematite to Ferrimagnetic Spherical Barium-Ferrite Nanoparticles for Particulate Recording Media

We used a modified, two-step hydrothermal process to produce worm-shaped antiferromagnetic hematite-barium iron oxide particles and converted them to 25-45 nm spherical ferrimagnetic barium-ferrite (S-BaFe) nanoparticles for high-density magnetic recording media application. Saturation magnetization and coercivity of the S-BaFe nanoparticles were 50.7 emu/g and 4311 Oe, respectively. The thermal stability of KuV/k B T ≈ 81 was estimated for the S-BaFe nanoparticles from time-dependent remanent coercivity measurements.