title: Synthesis and heating effect of iron/iron oxide composite and iron oxide nanoparticles.
abstract: Fe/Fe oxide nanoparticles, in which the core consists of metallic Fe and the shell is composed of Fe oxides, were obtained by reduction of an aqueous solution of FeCl3within a NaBH4solution, or, using a water-in-oil micro-emulsion with CTAB as the surfactant. The reduction was performed either in an inert atmosphere or in air, and passivation with air was performed to produce the Fe/Fe3O4core/shell composite. Phase identification and particle size were determined by X-ray diffraction and TEM. Thermal analysis was performed using a differential scanning calorimeter. The quasistatic magnetic properties were measured using a VSM, and the specific absorption rates (SARs) of both Fe oxide and Fe/Fe3O4composite nanoparticles either dispersed in methanol or in an epoxy resin were measured by Luxtron fiber temperature sensors in an alternating magnetic field of 150 Oe at 250 kHz. It was found that the preparation conditions, including the concentrations of solutions, the mixing procedure and the heat treatment, influence the particle size, the crystal structure and consequently the magnetic properties of the particles. Compared with Fe oxides, the saturation magnetization (MS) of Fe/Fe3O4particles (100-190 emu/g) can be twice as high, and the coercivity (HC) can be tunable from several Oe to several hundred Oe. Hence, the SAR of Fe/Fe3O4composite nanoparticles can be much higher than that of Fe oxides, with a maximum SAR of 345 W/g. The heating behavior is related to the magnetic behavior of the nanoparticles.
authors.affiliation: Thayer School of Engineering, Dartmouth College, Hanover, NH, USA 03755-8000.
authors.forename: Q
authors.initials: Q
authors.lastname: Zeng
authors.affiliation: Thayer School of Engineering, Dartmouth College, Hanover, NH, USA 03755-8000.
authors.forename: I
authors.initials: I
authors.lastname: Baker
authors.affiliation: Thayer School of Engineering, Dartmouth College, Hanover, NH, USA 03755-8000.
authors.forename: J A
authors.initials: JA
authors.lastname: Loudis
authors.affiliation: Thayer School of Engineering, Dartmouth College, Hanover, NH, USA 03755-8000.
authors.forename: Y F
authors.initials: YF
authors.lastname: Liao
authors.affiliation: Department of Surgery, Dartmouth Medical School, Hanover, NH, USA 03755.
authors.forename: P J
authors.initials: PJ
authors.lastname: Hoopes
keywords: Fe nanoparticles; SAR; chemical reduction; hyperthermia; magnetic nanoparticles