Nalazite se na CroRIS probnoj okolini. Ovdje evidentirani podaci neće biti pohranjeni u Informacijskom sustavu znanosti RH. Ako je ovo greška, CroRIS produkcijskoj okolini moguće je pristupi putem poveznice www.croris.hr
izvor podataka: crosbi

Study of the reduction and reoxidation of substoichiometric magnetite (CROSBI ID 149715)

Prilog u časopisu | izvorni znanstveni rad | međunarodna recenzija

Gotić, Marijan ; Koščec, Goran ; Musić, Svetozar Study of the reduction and reoxidation of substoichiometric magnetite // Journal of molecular structure, 924-926 (2009), SI; 347-354. doi: 10.1016/j.molstruc.2008.10.048

Podaci o odgovornosti

Gotić, Marijan ; Koščec, Goran ; Musić, Svetozar

engleski

Study of the reduction and reoxidation of substoichiometric magnetite

The commercial magnetite powder was characterised as substoichiometric magnetite (Fe2.93O4) with a small hematite fraction (∼7 wt%). It consisted of micrometer-sized particles of regular (octahedral) and irregular morphologies. Reference sample was subjected to reduction by hydrogen gas and reoxidation at a temperature of up to 600 °C. The oxidation experiments were performed in an oxygen stream. Reference sample oxidised to a maghemite– hematite mixture, whereas the fraction of each phase was very sensitive to the oxidation temperature. XRD and FT-IR spectroscopy indicated the superstructure character of obtained maghemite samples with the ordering of cation vacancies in the maghemite crystal lattice. Mössbauer spectroscopy was very sensitive to magnetite stoichiometry, however, it could not detect less than 10 wt% of hematite in the maghemite– hematite mixture. In reduction experiments, conditions for the reduction of reference sample to stoichiometric magnetite (Fe3.00O4) were found. The reduction was performed by hydrogen gas under static conditions (375 °C, 150 min). Under this static condition the relatively high amount of water condensed inside the evacuated quartz tube. The formation of water is due to the chemisorption of hydrogen molecules on the iron oxide, which then dissociate from iron oxide generating an intermediate hydroxyl group according to the general equations: 2O2-(s)+H2(g)→2OH-(s)+2e-and2OH-(s)→O2-(s)+□a+H2O(g), ; where (s) signifies a solid (hematite or substoichiometric magnetite), (g) a gas phase and □a an anionic vacancy formed in hematite or substoichiometric magnetite. Thus, in order to ensure a good reduction condition, water vapour was removed from the quartz tube and the tube was refilled with hydrogen gas every 30 min.

Magnetite ; Maghemite ; Hematite ; Stoichiometry ; Mossbauer ; FT-IR

U radu su objavljeni rezultati diplomskog rada dipl. inž. Gorana Koščeca. Rad je prezentiran na skupu XXIX European Congress on Molecular Spectroscopy : Molecular Spectroscopy and Molecular Structure 2008, održanom od 31.08.-05.09.2008., Opatija, Hrvatska.

nije evidentirano

nije evidentirano

nije evidentirano

nije evidentirano

nije evidentirano

Podaci o izdanju

924-926 (SI)

2009.

347-354

objavljeno

0022-2860

10.1016/j.molstruc.2008.10.048

Povezanost rada

Kemija

Poveznice
Indeksiranost