Study of the evolution in the iron oxide synthesis by hydrothermal process

A solution of Fe(NO3)(3) with a pH 9 was processed with a hydrothermal method in an autoclave. During the heating process samples were extracted at 140degreesC, 160degreesC, 180degreesC and 200degreesC and every hour for five hours after the autoclave reached 200degreesC. The samples were analyzed by Mossbauer spectroscopy and XRD. One can see the evolution of the process to obtain high-quality hematite. The main steps of this process are: at 140degreesC goethite was obtained, at 160 and 180degreesC a not well-defined stoichiometric hematite was obtained and finally at 200degreesC a well-defined hematite was obtained.