Room temperature synthesis of rod-like FeC₂O₄·2H₂O and its transition to maghemite, magnetite and hematite nanorods through controlled thermal decomposition

FeC(2)O(4)·2H(2)O nanorods with diameter of about 50 nm and length of up to several micrometers were synthesized at room temperature in a surfactant-assisted system, which was obtained by dissolving bis(2-ethylhexyl)sodium sulfosuccinate (AOT) in a mixed solution composed of water and ethylene glycol (EG). The influence of reaction conditions on the morphology of FeC(2)O(4)·2H(2)O is discussed in detail. Through direct thermal decomposition of FeC(2)O(4)·2H(2)O under different calcination conditions, maghemite (γ-Fe(2)O(3)), magnetite (Fe(3)O(4)) and hematite (α-Fe(2)O(3)) can be selectively obtained, preserving the rod-like morphology. Transmission electron microscope (TEM) and high-resolution transmission electron microscope (HRTEM) characterizations showed that the as-obtained iron oxide nanorods were composed of fine particles with different crystal orientations. The magnetic properties of the as-obtained iron oxide nanorods were systematically investigated.