Formation of rod-shaped BaFe_(12)O_(19) nanoparticles with well magnetic properties

摘要

A facile approach to preparing rod-shaped nanoparticles of barium ferrite was developed by combination of hydrothermal and annealing process in air. The magnetic nanorods with diameters ～40 nm and lengths ～150 nm were clearly visible in TEM and SEM images. Magnetic measurements showed that the rod-like BaFe_(12)O_(19) nanoparticles exhibited a great coercive field and high saturation magnetization of up to 4511 Oe and 67.3 emu/g, respectively. It is found that heat treatment in air can create less oxygen vacancies, which dramatically affects the Fe-O-Fe superexchange coupling. The results of this paper suggest that oxygen vacancies should be responsible for the decrease of saturation magnetization in nanosized magnetic materials.