Formation and hard magnetic properties of a hexagonal network of nickel ferrite nanoparticles

摘要

A novel hexagonal network structure formed by self-assembly of discrete nickel ferrite nanoparticles on a carbon-coated Cu grid is reported. Each hexagon consists of about 22 discrete nanoparticles with sizes from 120 to 250 nm. The side of the regular hexagon contains 4-6 discrete nanoparticles. The sample displays a large coercivity of 622.6 Oe, exhibiting a hard magnetic feature different from those of the corresponding bulk materials, and is closely related to the hexagonal network structure of nickel ferrite nanopaxticles.