Soft magnetic materials are used in within transformers and inductors throughout the power electronics found in every hybrid drive automobile. Transformer and inductor components are based on the design of a soft magnetic core, with copper windings surrounding it. This soft magnetic core serves to allow an increased magnetic flux to operate within the device. Losses in this system (electrical component inefficiencies) can be described as a combination of hysteresis loss and eddy current loss. It was hypothesized that synthesis of nanocomposites of complex binary and ternary superparamagnetic nanoparticles could realize control of macroscopic power electronic component inefficiencies through nanometer level adjustments to the material. Reported here are the syntheses of Fe50%Co50%/SiO2 and Fe49%Co49%V2%/SiO2 core/shell nanoparticles and their characterization. XRD, TEM, and SEM EDS analysis are all consistent with the binary and ternary magnetic system formations. Post-synthesis processing investigation was conducted to realize the maximum potential of these superparamagnetic core/shell nanoparticle systems through thermal annealing. The magnetic saturation could be increased by over 100% (exceeding 105 emu/g) through proper thermal annealing conditions, while maintaining their superparamagnetic quality. Studies of both the rapid thermal annealing of low-thermal-mass samples heated in excess of 80 oC/sec by an IR oven and the slow thermal annealing conducted over hours were conducted. Local maximum in the optimum magnetic properties as annealing condition severity were increased became apparent (see figure shown here), and interpreted as the initial optimization of the nanoparticle crystal structure. Degradation of magnetic saturation and superparamagnetism at high-enough and long-enough annealing temperatures was attributed to growth of nanoparticles through aggregation as indicated by the increase of magnetic coercivity to a non-zero value. Figure 1. <img src='https://acs-archive-assets2.s3.amazonaws.com/240nm/uploads/38875_acs_figure1.jpg' alt='' />

Synthesis of binary and ternary core/shell of superparamagnetic nanoparticles and their property improvements from thermal annealing

247th National Meeting (2014)

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