Nanocomposites and nanomaterials

Synthesis of magnetite nanoparticles by co-precipitation with different alkali under thermal treatment
O. Ye. Lipatov1, T.S. Antonenko2, N.O. Dudchenko2, A.B. Brik2, V.V. Ovsienko2, S.Yu. Tkachuk2
1 Educational and Scientific Institute “Institute of Geology” of Taras Shevchenko National University of Kyiv, Vasylkivska street, 90, Kyiv-03033, Ukraine.
E-mail: 19lipatov91@gmail.com

2 M.P. Semenenko Institute of Geochemistry, Mineralogy and Ore Formation of Natl. Acad. of Sci. of Ukraine, Palladina prosp, 34, Kyiv-03680, Ukraine. 

Nowadays, synthesis of magnetic nanoparticles is very important for solving both fundamental problems and many technological applications, for example, in magnetic storage media, for biomedical and biosensor application. All of these applications require magnetite particles with high magnetization values, a grain size less then 100 nm and a narrow size distribution [1]. The aim of this work was to synthesize highly magnetized magnetite particles under thermal treatment, using iron chlorides and various alkaline reagents. 
For magnetite synthesis, iron (II) chloride tetrahydrate (FeCl2·4H2O), iron (III) chloride hexahydrate (FeCl3·6H2O) and hydrochloric acid (HCl) have been used. The following alkaline reagents were used: potassium hydroxide (KOH), sodium hydroxide (NaOH), ammonium hydroxide (NH4OH). Magnetite nanoparticles were prepared by method of co-precipitation of Fe3+ and Fe2+ salts in alkaline medium. The preparation of the reagents was performed as follows: 2M FeCl2·4H2O and 1M FeCl3·6H2O was dissolved in 1M HCl. Then 2M alkali was added to the salts solution in hydrochloric acid, and the suspension was left under stirring at 95 °C for 20 min in a thermostat. The obtained samples were investigated by X-ray diffraction and magnetometry methods. Characteristic peaks in XRD pattern of obtained samples (for example, 4,86Å, 2,95Å, 2,52Å, 2,10Å, 1,61Å, 1,48Å) were attributed to magnetite. The saturation magnetizations of the obtained samples vary significantly. The saturation magnetization of the sample, obtained using sodium hydroxide was 20 Am2/kg; using potassium hydroxide – 28 Am2/kg; using ammonium hydroxide – 55 Am2/kg. We could conclude that the magnetization of obtained magnetite samples is rather high and makes them promising for different application.

1.	Blaney L. Magnetite (Fe3O4): Properties, Synthesis, and Applications // Paper 5. -2007. -15. -P. 33-81.