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XRD study of the thermal decomposition of iron choline citrate

Thermal decomposition of various iron-organic compounds has been widely used in the synthesis of magnetic iron oxides. Thermal decomposition of iron-organic compounds may be technologically interesting for the production of magnetic oxides because of its simplicity and economic value. Under well defined experimental conditions, at rather low temperatures and short reaction periods, it is possible to obtain ultrafine -Fe2O3 or Fe3O4 particles with desirable magnetic properties [S. Musić, M. Ristić, S. Popović, J. Radioanal. Nucl. Chem., 121 (1988) 61 and S. Musić, M. Gotić, S. Popović, I. Czakó-Nagy, Materials Letters, 20 (1994) 143]. In the present work we focus on the thermal decomposition of iron choline citrate, C33H57Fe2N3O24. Starting compound was heated in a tubular furnace in the temperature range from room temperature up to 460 oC for various periods. The samples were cooled down by either (a) quenching in a bidestilled water or (b) slow cooling in air. In air, self-propagating burning of samples preceded the cooling process. The thermal decomposition products were examined by X-ray powder diffraction. The XRD patterns were analysed by the individual profile fitting method [H. Toraya, J. Appl. Cryst. 19 (1986) 440]. The starting crystalline material became amorphous at ~220 oC. Further heating caused appearance of iron oxides, Fe3O4 and -Fe2O3, as only crystalline products, with Fe3O4 as the dominant phase in the rapidly cooled samples, while -Fe2O3 was dominant phase in the air cooled. The both crystalline phases showed broadened diffraction lines indicating nanosized crystallites, Fe3O4 having smaller crystallites. Also, Fe3O4 had smaller unit-cell parameter than that given in the JCPDS Powder Diffraction File, possibly indicating a substoichiometry. 57Fe Mössbauer spectroscopic measurements confirmed the results of XRD study.

thermal decomposition. Iron choline citrate. XRD

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