Novel Core-Shell Magnetic Nanoparticles: Synthesis, Magnetism and Applications

Dr. You Qiang
Department of Physics
University of Idaho

Magnetic nanoparticles (MNPs) have gained increased attention recently for many applications. Most MNPs or beads currently used in those applications are based on iron oxides with very low specific magnetic moments of ~30 emu/g. In this presentation, I report room-temperature synthesis of novel iron-iron oxide core-shell MNPs by a newly developed nanocluster source.  Monodispersive iron MNPs with size of diameters from 1 to 100 nm are produced in a cluster source chamber and then transmitted into the reaction chamber where a small partial pressure of O₂ is present so that the iron MNPs are coated with uniform iron oxide shell MNPs. These shells act as passivation layers preventing further oxidation of the cores upon subsequent or continued exposure to air. The core-shell MNPs are superparamagnetic at room temperature for sizes less than 15 nm, and then become ferromagnetic when the cluster size increases. The specific magnetic moment of core-shell MNPs is size dependent and increases rapidly from about 80 emu/g at the size of 3 nm to over 200 emu/g up to the size of 100 nm. The examples of utilizations of high magnetic moment MNPs are: 1) MNPs in cancer treatment; 2) MNP-chelator conjugates for environmental remediation and spent nuclear fuel recycling, and 3) REE (real earth elements) recovering for high-tech applications.

*Research supported by NIH, DOE-BES, and NSF-EPSCoR.

Bio: Dr. Qiang is a full professor of physics and full professor in the Environmental Science Program at the University of Idaho. He received his MS degree 1985 at the Harbin Institute of Technology and Chinese Academy of Space Technology, and Ph.D. in 1997 at the University of Freiburg, Germany. He was a research faculty at the University of Nebraska-Lincoln from 1999 to 2002. Dr. Qiang’s research focuses on magnetism and magnetic nanomaterials. He has studied magnetic nanoparticles and nanocomposites for more than 30 years. His expertise includes: synthesis of monodispersive nanoclusters and nanocluster-assembled composites; characterization of magnetic and optical properties as well as transport properties by conductivity, optics, susceptibility and theoretical investigation. He applies magnetic nanomaterials in energy, environmental and biomedical science and nanotechnology.  Presently Dr. Qiang’s research interests are a) Nano-nuclear technology and magnetic separation nanotechnology for used nuclear fuel recycling; b) High temperature ferromagnetism and giant magnetoresistance of semiconductor oxide nanomaterials for spintronics; and c) Iron-based magnetic nanoparticles for cancer treatment and environmental remediation.