Structural and magnetic properties of spark plasma sintered Co-Mg-Zn substituted Ba-Sr hexagonal ferrite magnets

[Display omitted] •Co-Mg-Zn substituted hexaferrites were processed by spark plasma sintering.•MS of 64emu/g and HC of 3.9kOe were obtained for SPSed sample.•Temperature dependent magnetization studies were performed.•Stoner Wohlfarth model for single domain was studied for the samples. The effect of conventional and spark plasma sintering processes on the structural and magnetic properties of Ba0.5Sr0.5Fe12−2xCox(MgZn)x/2O19 (x=0.2, 0.4 and 0.6) was investigated in this study. XRD patterns of both conventionally sintered (CS) and spark plasma sintered (SPS) samples with x=0.2 and 0.4 showed the crystallization of Ba0.5Sr0.5Fe12O19-phase with space group of P63/mmc. However, in the case of SPS sample with x=0.4, a secondary peak of α-Fe2O3 was observed. SEM analysis on the SPS samples revealed dense morphology with low porosity; while the CS samples showed the presence of aggregated particles with spherical shapes. Maximum values of saturation magnetization, MS (58emu/g) and coercivity, HC (3.5kOe) were obtained for the CS samples with x=0.4; while their SPS counterparts revealed increased MS (65emu/g) and HC (3.9kOe) values. The observed magnetization reversal behaviour for both sintering conditions were not smooth in the case of x=0.2, which indicated the existence of two-phase behavior. The temperature dependent magnetization studies for x=0.2 and 0.4 were performed in order to analyze the variation in Curie temperature against Co-Mg-Zn substitution and the obtained results are discussed on the basis of crystallization of hexaferrite-phase.