Effects of Co-Mn-Ti and Zn-Mg-Ti Substitutions on the Structural, Magnetic and Physical Properties of Barium Hexaferrites Synthesized by Co-Precipitation Method

Abstract

Barium hexaferrite nanoparticles, substituted with Co-Mn-Ti and Mg-Zn-Ti, with nominal compositions of BaCo $_x$ Mn $_x$ Ti $_{2x}$ Fe $_{12-4x}$ O $_{19}$ and BaZn $_x$ Mg $_x$ Ti $_{2x}$ Fe $_{12-4x}$ O $_{19}$ at $x = 0.0$ , $0.5, 0.7$ , and $0.9$ , were synthesized by using chlorides in the co-precipitation method. X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), field emission scanning electron microscopy (FE-SEM), and vibrating sample magnetometry (VSM) were employed to study the structural, physical, morphological, and magnetic properties of the samples. The XRD results indicate that single-phase barium hexaferrite can be achieved with a Fe $^{3+}$ /Ba $^{2+}$ molar ratio of 4 and when calcined at 1000 °C, and all of the samples were synthesized using these conditions. The structural parameters such as the lattice constants ( $a$ and $c$ ), cell volume $(V)$ , and crystallite size $(D)$ were calculated from the XRD data. The FTIR results show the characteristic absorption bonds for barium hexaferrite. The FE-SEM micrographs confirm the presence of hexagonal platelet structures. The particle sizes for both compositions were decreased by increasing the dopant levels and reducing the iron content. The hysteresis loops indicate that, by increasing the fraction of the substituted ions from $x = 0.0$ to $0.9$ , the saturation magnetization and coercivity were constantly decreased in both compositions, and the magnetic properties were changed from hard to soft.