Nanophase Magnetic Materials: Synthesis and Properties

摘要

Self-assembly preparative techniques in confinedmedia that lead to magnetic materials with nanometer dimensionsare described. Synthesis of nanoparticles using the restrictedenvironments offered by surfactant systems such as water-in-oilmicroemulsions (reverse micelles) provide excellent control overparticle size, inter-particle spacing, and particle shape. Theseenvironments have been used in the synthesis of #gamma#-Fe_2O_3, Fe_3O_4, MnFe_2O_4, CoFe_2O_4, Fe and Fe/Auwith particle sizes ranging from 10-20 nm. The controlledenvironment of the reverse micelle also allows sequentialsynthesis, which can produce a core-shell type structure (e.g., ironnanoparticles with gold coatings). Lyotropic liquid crystal mediaalso offer template effects for the synthesis of non-sphericalmagnetic nanostructures. The structures, theory and modelingconcepts and novel physical properties of these materials arediscussed with emphasis given to the differences between courseand fine grained magnetic materials.