Sol-gel auto-combustion synthesis of double metal-doped barium hexaferrite nanoparticles for permanent magnet applications

In the current work, BaZnxZrxFe12-2xO19 (x = 0.00-0.15) sub-micron particles synthesis with the help of the solgel auto-combustion technique has been carried out. XRD studies reveal the single BaM (barium hexaferrite of Mtype) phase formation and undesirable phases such as BaFe2O4 and alpha-Fe2O3 absent. The FE-SEM micrographs suggest that the size of grain increases from 241 nm (x = 0.00) to 280 nm (x = 0.15) with a substitution level. The enhancement in grain size with composition has been also confirmed by the dynamic light scattering technique (DLS). The coercivity (Hc) has been continuously decrease from 5363 Oe (x = 0.00) to 4211 Oe (x = 0.15) with increase in non-magnetic dopant concentration. On the other hand, the saturation magnetization (Ms) value increases from 70.87 emu/g (x = 0.00) to 87.04 emu/g (x = 0.15) with substitution. In the sol-gel auto-combustion synthesis of M-type hexaferrite, fuel plays an important role. It affects the magnetic properties, surface morphology, and calcination temperature of hexaferrite. In the present study, synthesis of Zr4+-Zn2+ doped BaM having a low composition (x = 0.00-0.15) using tartaric acid as fuel is first reported. The enhanced magnetic properties of Zr4+-Zn2+ doped BaM samples over undoped samples can be used in permanent magnet appliances.