Surface functionalization of magnetite nanoparticle: A new approach using condensation of alkoxysilanes

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Rodriguez, A. F. R.
Costa, T. P. [UNESP]
Bini, R. A. [UNESP]
Faria, F. S. E. D. V.
Azevedo, R. B.
Jafelicci, M. [UNESP]
Coaquira, J. A. H.
Martinez, M. A. R.
Mantilla, J. C.
Marques, R. F. C. [UNESP]

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Elsevier B.V.


In this study we report on successful production of two samples (BR15 and BR16) comprising magnetite (Fe3O4) nanoparticles (similar to 10 nm) surface-functionalized via hydrolysis and condensation of alkoxysilane agents, namely 3-aminopropyl-trimethoxisilane (APTS) and N-propyl-trimethoxisilane (NPTS). The as-produced samples were characterized using transmission electron microscopy (TEM), x-ray diffraction (XRD), magnetization measurements (5 K and 300 K hysteresis cycles and zero field-cooled/field-cooled measurements), and Mossbauer spectroscopy (77 and 297 K). The Mossbauer data supported the model picture of a core-shell magnetite-based system. This material system shows shell properties influenced by the surface-coating design, either APTS-coated (BR15) or APTS+NPTS-coated (sample BR16). Analyses of the Mossbauer spectra indicates that the APTS-coated sample presents Fe(III)-rich core and Fe(II)-rich shell with strong hyperfine field; whereas, the APTS+NPTS-coated sample leads to a mixture of two main nanostructures, one essentially surface-terminated with APTS whereas the other surface-terminated with NPTS, both presenting weak hyperfine fields compared with the single surface-coated sample. Magnetization measurements support the core-shell picture built from the analyses of the Mossbauer data. Our findings emphasize the capability of the Mossbauer spectroscopy in assessing subtle differences in surface-functionalized iron-based core-shell nanostructures.



Magnetite nanoparticles, Surface-functionalization, Hydrolysis and condensation reactions, X-ray diffraction, Mossbauer spectroscopy, Zero-field-cooled/field-cooled traces

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Physica B-condensed Matter. Amsterdam: Elsevier Science Bv, v. 521, p. 141-147, 2017.