Synthesis and characterization of stable colloidal Fe/sub 3/O/sub 4/ particles in water-in-oil microemulsions

The authors have prepared nanometer-size magnetite particles in Aerosol OT (AOT)/water/iso-octane water-in-oil (w/o) microemulsions. The sizes of the particles in the colloids were inferred from dynamic light scattering (DLS) and were on the order of one nanometer. Those in dried samples were measured using transmission electron microscopy (TEM) and were 5-20 nm. This implies that aggregation occurs during drying. X-ray diffraction showed that the particles' phase was consistent with magnetite. Magnetic properties were studied using a superconducting quantum interference device (SQUID) magnetometer. The colloids showed a superparamagnetic behavior and the dried samples showed a ferromagnetic behavior, supporting the size measurements using DLS and TEM, respectively.<
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