Refinement of Magnetite Nanoparticles by Coating with Organic Stabilizers.
Magnetite nanoparticles are of great importance in nanotechnology and nanomedicine and have found manifold applications. Here, the effect of coating of magnetite nanoparticles with organic stabilizers, such asO-phosphoryl ethanolamine, glycerol phosphate, phospho-l-ascorbic acid, phospho-d,l-serine, glycolic acid, lactic acid, d,l-malic acid, and d,l-mandelic acid was studied. Remarkably, this procedure led to an improvement of saturation magnetization in three cases rather than to an unfavorable decrease as usually observed. Detailed X-ray powder diffraction investigations revealed that changes in the average crystallite occurred in the coating process. Surprisingly, changes of the average crystallite sizes in either direction were further observed, when the exposure time to the stabilizer was increased. These results imply a new mechanism for the well-known coating of magnetite nanoparticles with stabilizers. Instead of the hitherto accepted simple anchoring of the stabilizers to the magnetite nanoparticle surfaces, a more complex recrystallization mechanism is likely, wherein partial re-dispersion of magnetite moieties from the nanoparticles and re-deposition are involved. The results can help producers and users of magnetite nanoparticles to obtain optimal results in the production of core shell magnetite nanoparticles.
National Institute of Research and Development for Isotopic and Molecular Technologies, Donat 67-103, RO-400293 Cluj-Napoca, Romania. moni3_circu@yahoo.com.
Monica
M
Cîrcu
National Institute of Research and Development for Isotopic and Molecular Technologies, Donat 67-103, RO-400293 Cluj-Napoca, Romania. alexandrina.nan@itim-cj.ro.
Alexandrina
A
Nan
National Institute of Research and Development for Isotopic and Molecular Technologies, Donat 67-103, RO-400293 Cluj-Napoca, Romania. borodi@itim-cj.ro.
Gheorghe
G
Borodi
National Institute of Research and Development for Isotopic and Molecular Technologies, Donat 67-103, RO-400293 Cluj-Napoca, Romania. liebscher@chemie.hu-berlin.de.|Department of Chemistry, Humboldt-University Berlin, Brook-Taylor-Str. 2, 12489 Berlin, Germany. liebscher@chemie.hu-berlin.de.
Jürgen
J
Liebscher
National Institute of Research and Development for Isotopic and Molecular Technologies, Donat 67-103, RO-400293 Cluj-Napoca, Romania. rodica.turcu@itim-cj.ro.
Rodica
R
Turcu
X-ray photoelectron spectroscopy; X-ray powder diffraction; coating; crystallite size; magnetic measurements; magnetite nanoparticles