Naslov
Chemical and microstructural properties of iron oxide powders obtained from FeCl3 solutions with decomposing urea

Autori
Musić, Svetozar ; Maljković, Miroslava ; Popović, Stanko

Izvornik
Ach : models in chemistry (1217-8969) 136 (1999), 3; 299-316

Vrsta, podvrsta i kategorija rada
Radovi u časopisima, članak, znanstveni

Sažetak
Iron oxides (group name) were precipitated from FeCl3 solutions with decomposing urea. Chemical and microstructural properties of iron oxide powders were investigated by X-ray diffraction, Fourier transform infrared spectroscopy, TGA/DTA analysis and transmission electron microscopy. In all precipitation systems, b-FeOOH was formed in the early stage of FeCl3 hydrolysis. It was found that the presence of b-FeOOH phase in the precipitates could be preserved up to pH~9, in consequence of a controlled increase of pH. The fraction of b-FeOOH in the precipitates with respect to pH depended on the concentrations of FeCl3 and urea. With an increase of pH, caused by the chemical decomposition of urea, there was also the formation of amorphous iron(III)-hydroxide, in parallel to the already formed b-FeOOH. Amorphous iron(III)-hydroxide was unstable and it transformed further to a-FeOOH and/or a-Fe2O3. The thermal behavior of iron(III)-oxyhydroxides was dependent on their chemical and microstructural properties. The mechanism of phase transitions is discussed. The influence of experimental conditions on size and morphology of the particles of iron oxides was determined.

Izvorni jezik
Engleski

Znanstvena područja
Kemija

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