NMR characterization of Co sites in La+Co-doped Sr hexaferrites with enhanced magnetic anisotropy

Cation distribution analysis of Sr-La-Co M-type ferrites by neutron diffraction, extended X-ray absorption fine structure and X-ray magnetic circular dichroism

“…When the results obtained using these techniques are consistent, we can be confident with the validity of the conclusion. Furthermore, other previous studies also have suggested a possibility of 4f 1 for the cobalt preferential site from 57 Fe and 59 Co NMR analysis 7), 8) and neutron diffraction, 9) namely, those results are consistent with our analysis results.…”

Recent improvement of hard ferrite permanent magnets based on La–Co substitution

“…In agreement with the magnetic measurements, the presence of these magnetic impurities can be partly responsible for both the decrease of the coercive field and the decrease of the rectangularity for x > 0.2. The cationic distribution of Co 2+ in Sr 1−x La x Fe 12−x Co x O 19 hexagonal ferrites was recently investigated by Möss-bauer spectrometry, Raman spectroscopy, and nuclear magnetic resonance [5][6][7][8][9][10]. It was shown that most of the Co 2+ is substituted for Fe 3+ in the octahedral 4f 2 and 2a sites, in agreement with the magnetization measurements.…”

“…The intrinsic magnetic properties (anisotropy field, saturation magnetization) being strongly dependent on the atomic magnetism, investigations on the sublattice occupation of Co 2+ in the M-hexagonal crystal were recently performed for the fundamental understanding of this beneficial effect [5][6][7][8][9][10]. M ferrites crystallize in a hexagonal structure with 64 ions per unit cell on 11 different symmetry sites (P6 3 /mmc space group).…”

Improvement of the coercivity of strontium hexaferrite induced by substitution of Al3+ ions for Fe3+ ions

“…For the magnetic moment of each Fe 3+ ion is 5l B , the net magnetic moment per unit cell is 40l B and spinning upward. The magnetic properties of the SrFe 12 O 19 are mainly originated from the contribution of Fe 3+ ions located at 2a, 2b and 12k sites [32][33][34]. Theoretical research indicates that the Fe 3+ ions located at 12k and 2a sites are substituted by the Al 3+ ions when Al incorporates into M-type hexaferrite [27], which will make the net magnetic moments per unit cell decrease, that is, saturation magnetization of the SrAl x Fe 12Àx O 19 decreases with increasing annealing temperature and the nominal Al content, so the saturation magnetization of the sample decreases.…”