Structural and magnetic properties of BaFe12−2xTixRuxO19

Barium hexaferrite samples BaFe12−2xTixRuxO19 were prepared by ball milling and their structural and magnetic properties were investigated using X-ray diffraction, TEM, Mössbauer spectroscopy, and vibrating sample magnetometry. It was found that the particle size increases appreciably, and the crystallinity improves with Ti–Ru substitution. Mössbauer spectroscopy revealed that the substitution of Fe3+ ions occurs at the 4f2 and 4f1 + 2a sites for low substitution, and substitution at the 2b site occurs for x ≥ 0.2. The saturation magnetization increases up to x = 0.2, and then starts to decrease for higher x values, while the coercivity decreases monotonically, recording a reduction of 55% at x = 0.4. These results were interpreted in terms of the site preferential occupation of the Ti2+ and Ru4+ ions. The thermomagnetic curves for all samples showed Hopkinson peaks indicating the presence of small superparamagnetic particles in the samples. The sample with x = 0.0 was found to consist of purely superparamagnetic particles, while the substituted samples were found to contain only 22–30% of the powders’ mass as superparamagnetic particles.