Synthesis and evaluation of physical and magnetic properties of doped barium hexaferrite with BaZn0.6Zr0.3X0.3Fe10.8O19 (X=Ti,Ce,Sn) composition

In this research, barium hexaferrite samples with BaZn0.6Zr0.3X0.3Fe10.8O19 (X=Ti,Ce,Sn) composition were synthesized via mechanical activation method and were evaluated by simultaneous thermal analysis (STA), X-ray diffraction (XRD), field emission electron microscopy (FE-SEM) and vibrating sample magnetometer (VSM). All of the synthesized samples were almost single phase and with average particles size of about 450 nm and 250 nm for samples without and with dopant respectively. Significant change in magnetic properties of barium hexaferrite were observed with effect of substitution of Fe ions. According to the results maximum magnetic saturation (33.1 emu/g) and minimum coercivity force (8.14 Oe) were related to samples with composition of BaZn0.6Zr0.3Ti0.3Fe10.8O19 and BaZn0.6Zr0.3Sn0.3Fe10.8O19 respectively

Synthesis of novel hard/soft ferrite composites particles with improved magnetic properties and exchange coupling

SrFe12O19/Zn0.4Co0.2Ni0.4Fe2O4 hard/soft ferrite composite particles with 20, 40, 60 and 80 wt.% of soft phase were prepared by one-pot sol-gel auto-combustion and physical mixing methods. Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), field emission scanning electron microscope (FESEM) and vibrating sample magnetometer (VSM) were used to characterize the structural and magnetic properties of the samples. XRD spectrum revealed the formation of mixed ferrite phases in the composite particles. The hysteresis loops of the samples showed the presence of exchange coupling between the hard and soft ferrites. The composite particles with 20 and 60 wt.% of the soft phase demonstrated the highest Mr/Ms ratio, i.e. 0.29 and 0.28, respectively. In addition, the highest Ms, Mr and Hc were achieved in the composite particles with 40, 60 and 20 wt.% of the soft phase, respectively. Compared to the physical mixing method (PM), the composite particles prepared by the sol-gel auto-combustion method (OP) demonstrated better magnetic properties. The exchange coupling interaction between the hard and soft ferrite phases was similar in both methods. These composite particles exhibited magnetically single phase behaviour, however, the saturation magnetization was lower in the physical mixing pared to that of the one-pot method