One-Pot Reaction and Subsequent Annealing to Synthesis Hollow Spherical Magnetite and Maghemite Nanocages.

Water-soluble hollow spherical magnetite (Fe(3)O(4)) nanocages (ca. 100 nm) with high saturation magnetization are prepared in a one-pot reaction by sol-gel method and subsequent annealing to synthesise the maghemite (gamma-Fe(2)O(3)) nanocages with similar nanostructures. The nanocages have been investigated by powder X-ray diffraction (XRD), transmission electron microscope (TEM), high-resolution transmission electron microscope (HRTEM), and superconducting quantum interference device (SQUID). The results indicated that glutamic acid played an important role in the formation of the cage-like nanostructures.