Magnetic properties of Sr0.95Nd0.05Fe12-xScxO19 hexaferrite nanoparticles

Abstract

Sr0.95Nd0.05Fe12-xScxO19 (0 ≤ x ≤ 1.56) nanocrystallites, 50–100 nm thick, were obtained by citric sol-gel method. Single P63/mmc phase with lattice parameters increasing continuously with x was proved by X-ray diffraction. Scanning electron microscope control of the microstructure shows a decrease in particle size with increasing x from 1000 to ∼250 nm. Saturated hysteresis loops were obtained in field of 5 T and magnetization switching via curling mode was observed for crystallites with sizes from 1000 to ∼600 nm. For smaller particles magnetization was switched via coherent reorientation. The effect of doping on magnetic properties was apparent in samples containing more than one Sc3+ ion substituting Fe3+ pro one unit cell (x ≥ 0.60). The saturation magnetization was found to increase on cooling from 300 K and for samples with x ≥ 0.60 exhibits local maximum at Tcone temperatures considerably lower in comparison with those of bulk counterparts. The appearance of conical magnetic order is reflected in temperature dependences of extrinsic magnetic properties, coercivity and remanence, which decrease also on doping. Temperature variation of magnetization in zero field cooling/field cooling modes shows that Tcone is shifted downwards with increasing field.