ABSTRACT
The synthesis of magnetic nanoparticles has been an active area of research since the development of ferrofluids in the 1950s and 1960s. As with many other inorganic nanoparticles, methods for the synthesis of magnetic nanoparticles are generally categorized as either “top-down” or “bottom-up” approaches. Top-down methods involve starting with bulk material and achieving nanoscale features through mechanical or chemical processes. A traditional top-down approach involves high-energy ball-milling of bulk material until particle dimensions reach the nanoscale. Although this process is well suited to producing large quantities of material, it is plagued by quality control issues such as impurities from the milling media and poor control over the shape and size dispersion of the resultant nanoparticles. Lithographic techniques represent an alternative top-down approach that affords excellent control over shape and size dispersion, but is limited to particles with diameters greater than 50 nm and have limited scalability.
