Mössbauer spectroscopy control of the preparation of citric- and mandelic acid functionalized nanomagnetites
Iron-oxide nanoparticles were prepared by two ways of chemical methods when the coprecipitated nanomagnetites were functionalized by different (citric and mandelic) carboxylic acids. The colloid samples were characterized by 57Fe Mössbauer spectroscopy, electron microscopy, RAMAN spectroscopy and magnetization measurements. Considerable paramagnetic contributions are present in the 80 K Mössbauer spectra in both citric acid coated and mandelic acid coated nanomagnetites. The 5 K measurement revealed that the paramagnetic component appearing at 80 K can represent a superparamagnetic fraction due to the small particle size in the case of mandelic acid functionalized sample. However, in the case of citric acid functionalized nanomagnetite sample, the paramagnetic components occurring also in the 5 K spectra can be associated with components of precursors and of by-product phases.
Keywords57Fe Mössbauer spectroscopy Iron-oxide nanoparticles Carboxylic acid coating Superparmagnetism Control of synthesis
The financial supports from the CAPES (No A127/2013) and NKFIH-OTKA (No K115913 and K115784) as well as Hungarian-Croatian S&T (No TÉT_16-1-2016-0002) grants are acknowledged.