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From iron(III) precursor to magnetite and vice versa


Gotić, Marijan; Jurkin, Tanja; Musić, Svetozar
From iron(III) precursor to magnetite and vice versa // Materials Research Bulletin, 44 (2009), 10; 2014-2021 doi:10.1016/j.materresbull.2009.06.002 (međunarodna recenzija, članak, znanstveni)


Naslov
From iron(III) precursor to magnetite and vice versa

Autori
Gotić, Marijan ; Jurkin, Tanja ; Musić, Svetozar

Izvornik
Materials Research Bulletin (0025-5408) 44 (2009), 10; 2014-2021

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

Ključne riječi
Iron oxide ; gamma-irradiation ; microemulsion ; magnetite ; Mössbauer spectroscopy

Sažetak
The syntheses of nanosize magnetite particles by wet-chemical oxidation of Fe2+ have been extensively investigated. In the present investigation the nanosize magnetite particles were synthesised without using the Fe(II) precursor. This was achieved by γ -irradiation of water-in-oil microemulsion containing only the Fe(III) precursor. The corresponding phase transformations were monitored. Microemulsions (pH ∼ 12.5) were γ -irradiated at a relatively high dose rate of ∼ 22 kGy/h. Upon 1 h of γ -irradiation the XRD pattern of the precipitate showed goethite and unidentified low-intensity peaks. Upon 6 h of γ -irradiation, reductive conditions were achieved and substoichiometric magnetite (∼ Fe2.71O4) particles with insignificant amount of goethite particles found in the precipitate. Hydrated electrons (ea q-), organic radicals and hydrogen gas as radiolytic products were responsible for the reductive dissolution of iron oxide in the microemulsion and the reduction Fe3+ → Fe2+. Upon 18 h of γ -irradiation the precipitate exhibited dual behaviour, it was a more oxidised product than the precipitate obtained after 6 h of γ -irradiation, but it contained magnetite particles in a more reduced form (∼ Fe2.93O4). It was presumed that the reduction and oxidation processes existed as concurrent competitive processes in the microemulsion. After 18 h of γ -irradiation the pH of the medium shifted from the alkaline to the acidic range. The high dose rate of ∼ 22 kGy/h was directly responsible for this shift to the acidic range. At a slightly acidic pH a further reduction of Fe3+ → Fe2+ resulted in the formation of more stoichiometric magnetite particles, whereas the oxidation conditions in the acidic medium permitted the oxidation Fe2+ → Fe3+. The Fe3+ was much less soluble in the acidic medium and it hydrolysed and recrystallised as goethite. The γ -irradiation of the microemulsion for 25 h at a lower dose rate of 16 kGy/h produced pure substoichiometric nanosize magnetite particles of about 25 nm in size and with the stoichiometry of Fe2.83O4.

Izvorni jezik
Engleski

Znanstvena područja
Kemija



POVEZANOST RADA


Projekt / tema
098-0982904-2952 - Sinteza i mikrostruktura metalnih oksida i oksidnih stakala (Mira Ristić, )
098-0982904-2955 - Odnosi struktura-svojstvo modificiranih polimernih materijala (Irina Pucić, )

Ustanove
Institut "Ruđer Bošković", Zagreb

Časopis indeksira:


  • Current Contents Connect (CCC)
  • Web of Science Core Collection (WoSCC)
    • Science Citation Index Expanded (SCI-EXP)
    • SCI-EXP, SSCI i/ili A&HCI
  • Scopus


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