Microstructure and magnetic properties of M-type strontium hexagonal ferrites with Y-Co substitution

•Y-Co substitution in strontium hexaferrites have been prepared and investigated systematically for the first time.•Lattice constants a and c for all the samples are very different with that of unsubstituted ferrites.•The Ms and Hc are very high, from which may provide an important significance of research and development of high performance products. According to the formula Sr0.95Y0.05Fe12−xCoxO19 (x=0.00, 0.08, 0.16, 0.24, 0.32, 0.40), the replacement of Y-Co in M-type strontium hexagonal ferrites have been successfully prepared by ceramic process for the first time. The phase compositions of magnetic powders were examined by X-ray diffraction. The results of XRD showed that the single phase was obtained in magnetic powders with the increase of Co content (x), and α-Fe2O3 occurred when x>0.24. The morphology of the magnets was investigated by scanning electron microscopy (SEM). The micro-morphology of the particles exhibited the uniform plane hexagonal structures of M-type ferrites with different Co content. Magnetic properties of the ferrite magnets were measured by a physical property measurement system-vibrating sample magnetometer (PPMS-VSM). The Ms increases constantly with the increase of Co content. The Hc first increases and then decreases with the increase of Co content, and the value of coercivity (Hc) is up to 3774 Oe when x=0.24.