Crystal structure, magnetic properties, and Raman spectra of solid solutions BaFe$_{12-x}$Al$_{x}$O$_{19}$

The crystal structures of solid solutions of hexagonal ferrites BaFe$_{12-x}$Al$_{x}$O$_{19}$ ($x$ = 0.1–1.2) have been studied using X-ray diffraction. It has been found that, at normal conditions, the samples are characterized by space group $P$6$_3$/$mmc$. It has been noted that the diamagnetic substitution of Al$^{3+}$ ions for Fe$^{3+}$ leads to a decrease in the unit cell parameters due to the smaller aluminum ion radius. The field dependences of the specific magnetic moment have been studied in fields of $\pm$2T at 5 and 300 K using vibrating magnetometry. It has been found that the specific magnetic moment decreases from 49.6 emu/g ($x$ = 0.1) to 32 emu/g ($x$ = 1.2) as the concentration of the diamagnetic ions increases. The microstructure has been studied using scanning electron microscopy. The Raman spectra have been measured in the range of 200–800 cm$^{-1}$.