Abstract: The BaSm0.3Fe11.7O19 ferrite fibers with diameters below 1μm were successfully fabricated by sol-gel method from starting reagents of metal salts and citric acid. The precursor and calcined products were characterized by means of thermogravimetric and differential thermal analysis (TG-DSC), X-ray powder diffraction (XRD), field emission scanning electron microscopy (FE-SEM) and vibrating sample magnetometer (VSM). The results showed that the pure BaSm0.3Fe11.7O19 ferrite phase was basically formed after calcined at 750 ℃ for 1 h. With the increase of calcination temperature and holding time, the grain growth take place, the fiber surface became much rougher and plate structure become more and more obvious. At the same time, the saturation magnetization (Ms) of BaSm0.3Fe11.7O19 ferrite fibers monotonously increased, while the coercivity (Hc) initially increased, reached a maximum value of 459.2 kA/m at grain size of 58.4 nm, and then decreased with further grain growth, indicating that the single-domain critical size of BaSm0.3Fe11.7O19 ferrite fibers may be around 60 nm. The difference of Ms and Hc measured at 300K and 77K are attributed to the surface spin order nanocrystalline BaSm0.3Fe11.7O19 ferrite.

Key words: Heat-treatment, BaSm0.3Fe11.7O19 ferrite, Fiber, Magnetic property