(679b) Tunable Magnetic Core-Shell Nanoparticles: An Interplay between Composition, Size, Shape and Architecture
In this work, a modified thermal decomposition method is used in order to control the composition, morphology, architecture of Fe3O4 nanostructures with critical dimensions between 20-30 nm. Initially, composition of the nanostructures is determined through the synthesis of an MxFe1-x oleate (M= Co2+, Ni2+, Fe2+/3+ or Mn2+/3+) during the initial precursor synthesis, where the Co dopant increases coercivity and Ni/Mn dopants increases the remanent magnetization. These precursors are then used to synthesize spheres, cubes, plates, and pyramids based on the ratio of oleate to oleic acid precursor via a steric hindrance mechanism on the difference surface facets. Finally, core-shell nanostructures, with conformal and non-conformal coatings, are fabricated through a subsequent deposition on a magnetic core, in order to facilitate magnetic coupling across the interface, and non-magnetic structures, to overcome the ~20 nm critical dimension that results in agglomeration of the particles. Furthermore, this two-step process allows for the synthesis of high aspect ratio 1D and 2D magnetic structures which have not been previously reported. In addition to standard characterization techniques, the chemical and structural control will be highlighted using high resolution electron microscopy and specially resolved energy spectroscopy coupled with magnetic characterization to introduce design parameter for engineered materials.