FeSiCrB amorphous soft magnetic composites filled with Co2Z hexaferrites for enhanced effective permeability

• Co 2 Z hexaferrites and FeSiCrB powders are compacted into toroidal Co 2 Z/FeSiCrB SMCs. • Air gaps between FeSiCrB powders are filled with Co 2 Z hexaferrites. • Co 2 Z hexaferrites increases the density of Co 2 Z/FeSiCrB SMCs and reduce Hc . • Co 2 Z hexaferrites increases conduction area and decreases demagnetization effect. • Co 2 Z/FeSiCrB SMCs possess the higher permeability and lower core loss than FeSiCrB SMCs. Z-type Sr 3 Co 2 Fe 24 O 41 hexaferrites (Co 2 Z hexaferrites) were synthesized with sol–gel method and were mechanically mixed with spherical Fe 88 Si 7 Cr 2.5 B 2.5 (FeSiCrB) amorphous powders, and then compacted to form toroidal Co 2 Z hexaferrites/FeSiCrB amorphous soft magnetic composites (Co 2 Z/FeSiCrB SMCs). The compositions, morphology and soft magnetic performance were characterized through SEM, XRD, VSM, EDS, B-H analyzer and impedance analyzer. All results reveal that Co 2 Z hexaferrites in Co 2 Z/FeSiCrB SMCs should mainly exist in air gaps between spherical FeSiCrB amorphous powders, leading to the increasing density. Saturation magnetization decreases a little for magnetic dilution and coercivity increases for the stronger magnetic interaction of Co 2 Z/FeSiCrB SMCs. The introduction of Co 2 Z hexaferrites in air gaps increases the conduction area of magnetic circuits and decreases the demagnetization effect, leading to the higher effective permeability of 27.4 for Co 2 Z/FeSiCrB SMCs, much higher than 25.0 for FeSiCrB SMCs. Furthermore, Co 2 Z/FeSiCrB SMCs present the smaller core loss and more stable DC bias characteristics owing to the insulating Co 2 Z hexaferrites.