Exchange-coupling behavior in soft/hard Li0.3Co0.5Zn0.2Fe2O4/SrFe12O19 core/shell composite synthesized by the two-step ball-milling-assisted ceramic process

Abstract

Soft/hard xLi0.3Co0.5Zn0.2Fe2O4@(1 − x)SrFe12O19 (x = 0.1, 0.2, and 0.3) core/shell magnetic composites have been synthesized by the two-step ball-milling-assisted ceramic process. X-ray diffraction (XRD), scanning electron microscopy (SEM), and vibrating sample magnetometer are employed to analysis of structural and magnetic features of synthesized samples. The analysis of XRD indicates the formation of hard/soft ferrite composites in combination with a small amount of the α-Fe2O3 phase. FT-IR analysis confirms the formation of soft/hard Li0.3Co0.5Zn0.2Fe2O4@SrFe12O19 ferrite composite with core/shell structure. Single smooth hysteresis loops of composites show the presence of exchange-coupling between hard and soft magnetic phases. Exchange-coupling behavior between hard and soft magnetic phases is also confirmed by the switching field distribution curves. Ferrite composite with 3.0:7.0 mass ratio of soft-to-hard magnetic phase has the highest specific saturation magnetization value (74.08 emu/g). The specific saturation magnetization (Ms) of ferrite composites is markedly increased compared with Li0.3Co0.5Zn0.2Fe2O4 and/or SrFe12O19. This is attributed to the exchange-coupling interaction between the hard and soft phases due to formation of core/shell structure. Two-step ball-milling-assisted ceramic process could be considered as a suitable method for synthesizing exchange-coupled magnet.