Correlation between Composition and Magnetic Properties of SrFe₁₂O₁₉/Co Nanocomposite Synthesized by the High Energy Ball-Milling Process

Abstract

Nanocomposites (NCs) (100-x) SrFe12O19/x Co (x = 10, 20, and 30 wt. %) were produced using the high energy ball-milling (HEBM) process. The effects of hard/semi-hard ratio and annealing temperature (800, 900, and 1000 °C) on the exchange-spring in magnetic NCs were discussed. X-ray diffraction examination showed the coexistence of M-type hexaferrite SrFe12O19 (SFO) as the hard phase and CoFe2O4 spinel ferrite (CFO) as the semi-hard phase. Using a scanning electron microscope (SEM), the morphology and elemental analysis of the NCs were analyzed. The magnetic performances were investigated via a vibrating sample magnetometer at room temperature. With increasing the CFO content and annealing temperature, the hysteresis loop became narrower and possessed semi-hard magnetic properties. The 10 wt. % Co NCs annealed at 800 °C had the highest coercivity of Hc = 4.2 kOe. These results are correlated with switching field distribution plots that have indicated the efficient exchange-spring between SFO and CFO phases NCs annealed at 800 °C. The studied samples can be a promising candidate in permanent magnets and magnetic recording media applications.