Solution Synthesis of Magnetic Nanoparticles

A number of practical applications have been envisioned using magnetic nanoparticles. Some potential applications include medical imaging, high-density data storage, and catalysis. On account of the unusual properties demonstrated by magnetic nanoparticles, much work remains to be done to gain a deeper understanding into the synthesis and characterization of these novel materials. Our studies have focused on two different systems, nickel and cobalt oxide. Nickel, while most energetically stable in the face-centered cubic (fcc) phase, has been prepared by our group in the meta-stable, hexagonally close-packed (hcp) phase, under relatively mild conditions. While hcp nickel has been prepared by various means in previous studies, our method, owing to its low-temperature, solution phase synthesis, enables a highly scalable synthetic route to production. Cobalt oxide has been formed in the wurtzite phase previously in our group, albeit with a cobalt impurity. Our work at present sought to examine the parameters that influence the formation of the wurzite phase of cobalt oxide versus the formation of the more energetically favorable rock-salt phase. Additional work focused on the preparation of cobalt oxide in either the rock-salt or wurtzite phase free of the cobalt impurity. Magnetic data were collected using a SQUID magnetometer to elucidate the magnetic character of both the rock-salt and wurtzite cobalt oxide nanoparticles.