Synthesis and Characterization of SrFe12O19/SiO2/TiO2 Composite Powder with Core/Shell/Shell Nanostructure

In this research study, the coating of titania particles on the SrFe12O19/SiO2 composite was successfully accomplished by the sol-gel process. For this purpose, first, the strontium hexaferrite particles were prepared by co-precipitation route with Fe3+/Sr2+ molar ratios of 11 and 12 and subsequent calcination treatment. The formation of single phase strontium hexaferrite particles, as hard magnetic cores of the composite, was attained in the molar ratio of Fe3+/Sr2+=12 after calcination at 950 °C. In the next step, the silica coating of hexaferrite particles was performed using the tetraethyl orthosilicate (TEOS) precursor via the Stöber method. In the end, the covering of titania particles on the SrFe12O19/SiO2 composite was carried out by utilizing titanium n-butoxide (TNBT) precursor. The as-prepared composites were characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), energy dispersive X-ray (EDX) and vibrating sample magnetometry (VSM) analyses. The results confirmed the core/shell/shell structure of the synthesized SrFe12O19/SiO2/TiO2 composite. The analysis of the magnetic properties showed that saturation magnetization (Ms) of strontium hexaferrite powder was obtained as 58 emu/g. After the successive coating of SiO2 and TiO2 shells, this amount has reached to 56 emu/g and 37 emu/g, respectively.