Nanocrystallites of the permanent magnetic material SrFe12O19 were synthesised using a conventional sol-gel (CSG) and a modified sol-gel (MSG) synthesis route. In the MSG synthesis, crystallite growth takes place in a solid NaCl matrix, resulting in freestanding nanocrystallites, as opposed to the CSG synthesis, where the produced nanocrystals are strongly intergrown. The resulting nanocrystallites from both methods exhibit similar intrinsic magnetic properties, but significantly different morphology and degree of aggregation. The nanocrystallites were compacted into dense pellets using a Spark Plasma Sintering (SPS) press, this allows investigating the influence of crystallite morphology and the alignment of the nanocrystallites on the magnetic performance. A remarkable correlation was observed between the crystallites morphology and their ability to align in the compaction process. Consequently, a significant enhancement of the maximum energy product was obtained after SPS for the MSG prepared sample (22.0 kJ/m3), compared to CSG sample, which achieved an energy product of 11.6 kJ/m3.

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The relationship between nanoparticle morphology, self-induced atomic/magnetic texture and magnetic properties of high-performance hexaferrite magnets is elucidated using neutron/X-ray pole figure analysis and neutron/synchrotron powder diffraction.

The degree of alignment and its influence on the coercive force in SrFe12O19 crystallites consolidated by SPS.

Combining multiple characterization probes (neutrons, X-rays, electrons) illustrated the hierarchical structure of exchange-spring nanocomposites & revealed unreported degradation of parent phase.