ACTA

Structure of Iron Oxide Nanoparticles Studied by ⁵⁷Fe NMR

P. Křišťan^a, V. Chlan^a, H. Štěpánková^a, R. Řezníček^a, P. Görnert^b, P. Payer^b
^aCharles University in Prague, Faculty of Mathematics and Physics, V Holešovičkách 2, 180 00 Prague 8, Czech Republic
^bInnovent e.V. Technologieentwicklung, Prüssingstr. 27 B, D-07745 Jena, Germany

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In this work we apply nuclear magnetic resonance (NMR) spectroscopy of ⁵⁷Fe nuclei for investigation of submicron and nanocrystalline iron oxide systems. The studied iron oxide particles are obtained from ferrous hydroxide gels (prepared from FeCl₂ and KOH) by aging at elevated temperatures (90 °C) with KNO₃ as oxidant. The ⁵⁷Fe NMR spectra of the samples are measured in temperature range 4.2-370 K in a zero external magnetic field. Signals of ⁵⁷Fe nuclei assigned to tetrahedral and octahedral iron sites are well resolved. The NMR spectra and their temperature dependences are compared with those of stoichiometric and nonstoichiometric magnetite single crystals, as well as with samples of maghemite.

DOI: 10.12693/APhysPolA.126.138
PACS numbers: 76.60.-k, 75.50.Gg, 75.50.Gg, 75.50.Tt