Improved magnetic and magnetoelectric properties in BaFe12O19 nanostructures.

The structural, magnetic and magnetoelectric properties were investigated for sol-gel prepared BaFe12O19 nanorods and plate-like nanoparticles. Based on comparative experiments with bulk ceramics, it is found that larger structural distortion is present in nanostructures, which could cause the enhancement of magnetocrystalline anisotropy and the off-center displacement of Fe3+ ions, and thus result in improved magnetic and magnetoelectric properties in BaFe12O19 plate-like nanoparticles. Meanwhile, the local (Fe2+-Fe3+) dipoles, which usually appear during a high temperature sintering process, can also contribute to the negative magnetoelectric effect of BaFe12O19 nanorods and a large room temperature magnetodielectric coefficient of about -13% is observed at 104 Hz and 9 kOe.