Magnetic structure of zinc-ferrite approaching nanometer sizes

A unit cell of a spinel ferrite is just under I nm, actually about 0.8 nm. Particles approaching this size can be expected to possess properties that differ from the bulk material. Bulk polycrystalline Zn-ferrite (ZnFe2O4) ha s been ball milled; after 50 h the average particle size is about 13 nm. Th e Fe-57 Mossbauer spectra at T = 4.2 K with and without a large (52 kOe) ma gnetic field applied longitudinally establish that the antiferromagnetic st ructure of the bulk has become ferrimagnetic in the ten nanometer particles via the transfer of some Zn cations from the A (tetrahedral) sites to the B (octahedral) sites. In addition, there is a large non-collinearity in the magnetic structure.