Ti-substituted barium hexaferrite BaFe 12 O 19 single crystals Ba-Fe 12−x Ti x O 19 with x up to 1.3 and sizes 2−8 mm were grown by spontaneous crystallization from molten sodium carbonate flux. The distribution of Ti on different crystallographic sites was determined from single crystal X-ray diffraction data. For low Ti contents up to x = 0.8 the unit cell expands; on further increase of the Ti amount the unit cell starts to shrink. This behavior for low Ti contents is most likely due to a reduction of Fe 3+ to Fe 2+ for charge balance. At higher Ti concentrations, supposedly vacancies in the transition metal substructure are formed. An increasing Ti concentration results in a monotonous reduction of the Curie temperature from 452 to 251 °C and the saturation magnetization at room temperature from 64.8 to 24.8 emu/g for powder samples and from 70.0 to 60.1 emu/g for single crystals (for x up to 0.78).

The barium hexaferrite, BaFe12O19, microcrystals were obtained by the flux crystal growth method and were characterized by XRD, SEM, and TEM methods. XPS measurements were carried out on a powder sample. The binding energy differences between the O 1s and cation core levels, ΔBa = BE­(O 1s) – BE­(Ba 3d5/2) and ΔFe = BE­(O 1s) – BE­(Fe 2p3/2), were used to characterize the valence electron transfer on the formation of Ba–O and Fe–O bonds. The chemical bonding effects were considered on the basis of our XPS results measured for BaFe12O19 and the earlier published structural and XPS data for other Ba- or Fe-containing oxide compounds. The band structure of BaFe12O19 was calculated by spin-polarized DFT methods and compared to the valence band spectrum measured by the XPS method.

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