https://doi.org/10.1140/epjs/s11734-025-01480-8
Regular Article
Effects of Fe substitution by Al on the structure and magnetic properties of BaFe10Al2O19 hexaferrites
1
Institute of Electronics, Bulgarian Academy of Sciences, Sofia, Bulgaria
2
Neofit Rilski South-Western University, 66 Ivan Mihailov Str., 2700, Blagoevgrad, Bulgaria
3
Institute of Low Temperature and Structure Research, Polish Academy of Sciences, Ul. Okólna 2, 50-422, Wroclaw, Poland
4
Greenmat, Chemistry Department, University of Liege, 11 Allée du 6 Août, 4000, Liège, Belgium
Received:
31
July
2024
Accepted:
20
January
2025
Published online:
5
February
2025
M-type hexaferrites find numerous important applications as permanent magnets, high-density recording media, microwave absorption devices and stealth technology among many others. Herein, we report the effects of diamagnetic dilution of exchange interactions in M-type hexaferrites expressed through the structural, morphological, and magnetic properties of Al-substituted barium hexaferrite (BaFe12−xAlxO19, x = 2) powders investigated by X-ray and neutron diffraction, scanning electron microscopy and SQUID magnetometry. X-ray and neutron powder diffractograms revealed the formation of well crystallized single phase in the P63/mmc space group. The presence of only one magnetic entity but in different valence states and the corresponding interactions of cations distributed in the crystal lattice sites contribute to the diverse magnetic behavior. Depending on the soft chemistry method, powder samples consisting of particles with an average size of 80–200 nm were produced. The particles with a size below 110 nm did not possess a completely formed hexagonal shape. The sonochemical co-precipitation powders have an average particle size of 160 nm with well-developed hexagonal shape and the hysteresis loop shape is typical for two magnetic phase material. The critical diameter for single-domain barium hexaferrite particles is about 460 nm and makes it plausible to infer that both preparation routes resulted in single-domain BaAl2Fe10O19 nanoparticles characterized by a narrow size distribution. The particles were agglomerated due to the strong attractive magnetic force and high surface energy of the nanoparticles. Room temperature values of the saturation magnetization Ms and coercive field Hc were 59 emu/g and 2.4 kOe for sonochemical co-precipitation powders contrasting to the 15 emu/g and 5.8 kOe for the auto-combustion counterparts. The temperature dependence of magnetization in ZFC and FC measurement at 100 Oe indicated occurrence of magnetic phase transitions in the temperature range 260–300 K for the sonochemical co-precipitation powders and around 80 K for the auto-combustion powders.
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Springer Nature or its licensor (e.g. a society or other partner) holds exclusive rights to this article under a publishing agreement with the author(s) or other rightsholder(s); author self-archiving of the accepted manuscript version of this article is solely governed by the terms of such publishing agreement and applicable law.
