engleski

Microstructural characterization of radiolytically synthesized feroxyhyte and magnetite nanoparticles

Iron(III) chloride deaerated alkaline aqueous colloidal solutions in the presence of 2- propanol and DEAE-dextran (diethylaminoethyl- dextran hydrochloride) were γ-irradiated with doses of 36 and 130 kGy. The dose rates were ~7 and ~31 kGy h-1. Substoichiometric magnetite nanoparticles ~4-5 nm in size formed at a dose of 36 kGy. The dose rate had an effect on the stoichiometry of the formed magnetite. At a dose of 130 kGy and the lower dose rate, the anisotropic d-FeOOH magnetic discs with a diameter of ~256 nm and thickness of ~40 nm self-assembled. At a dose of 130 kGy and the higher dose rate, the rolled rod-like d-FeOOH magnetic nanoparticles were formed having the diffraction patterns characteristic of tubular structures. The magnetic measurements showed exceptional intrinsic room-temperature magnetic properties of both d-FeOOH nanostructures with the Curie temperature above 300 K. In order to ascertain the formation of Fe(II) intermediate products prior to their oxidation, the γ- irradiated samples were isolated by admixing glycerol. The amounts of Fe(II) in glycerol- isolated solid samples were 9.9 % and 86.0 %, as determined by Mössbauer spectroscopy at doses of 36 and 130 kGy, respectively. Carbonate Green Rust I, GR(CO32-), and Fe(OH)2 intermediate phases were confirmed by XRD and Mössbauer spectroscopy.

gamma-irradiation ; amino dextran ; green rust ; iron(II) hydroxide ; feroxyhyte ; magnetite

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