Microwave-hydrothermal synthesis of monodispersed nanophase α-Fe2O3

Synthesis of monodispersed nanophase alpha -Fe2O3 (hematite) powder to be used as a red pigment in porcelains was investigated using microwave- hydrothermal and conventional-hydrothermal reactions using 0.018M FeCl3. 6H(2)O and 0.01M HCl solutions at 100 degrees -160 degreesC. Acicular and yellow beta -FeOOH (akaganite) particles 300 nm in length and 40 mn in thickness were dominantly formed at 100 degreesC after 2-3 h, while spherical alpha -Fe2O3 particles 100-180 nm in diameter were preferentially formed after 13 h using a conventional-hydrothermal reaction. However, a microwave-hydrothermal reaction at 100 degreesC led to monodispersed and red alpha -Fe2O3 particles 30-66 urn in diameter after 2 h without the formation of beta -FeOOH particles. In this paper, the effect of microwave radiation during hydrothermal treatment at 100 degrees -160 degreesC on the formation yield, kinetics, morphology. phase type, and color of alpha -Fe2O3 was investigated.