Structural and magnetic properties of Sn–Zn doped BaCo2Z-type hexaferrite powders prepared by citrate precursor method

Polycrystalline Sn–Zn substituted barium Z-type hexagonal ferrites powders Ba3Co2SnxZnxFe24−2XO41 (0≤X≤0.1) have been synthesized using the citrate precursor method. The effect of synthesis conditions on crystal structure, crystallite size, microstructure and magnetic properties was systematically studied. The results revealed that two steps annealing; pre-annealing of the hexaferrite citrate precursor at 600 °C for 4 h then post-annealed at 1250 °C for 5 h was required to form single Co2Z-type phase. Moreover, the critical Sn–Zn concentration, that was not destroy the symmetry of the hexagonal lattice, was found to be X=0.08. The crystallite size of the produced Sn–Zn doped Co2Z-type hexaferrite powders was in the range between 70 and 85 nm. Additionally, the lattice parameters, unit cell volume and the porosity were increased whereas the X-ray and bulk densities were decreased with increasing Sn–Zn concentration. The microstructure of the ferrite powders appeared as a hexagonal platelet-like structure. The saturation magnetization of Sn–Zn substituted Co2Z type hexaferrite was reached the maximum value (Ms=47.8 emu/g) at X=0.06 whereas it was reached the minimum value (Ms=43.4 emu/g) at X=0.1. Meanwhile, the coercivity and the squareness ratio were increased as X value increasing. - Highlights: ► Ba3Co2SnxZnxFe24−2XO41, X=0–0.1, are prepared by citrate precursor method. ► Single Z-type phase does not corrupt until X>0.08. ► Agglomeration of hexagonal-platelet like structure increases as X increasing. ► The preference of Sn4+ and Zn2+ ions is to occupy octahedral 4f2 sites. ► The superexchange interaction and Ms increase as X=0.06