Magnetic enhancement of γ-Fe2O3 nanoparticles by sonochemical coating

We show that sonochemistry is an efficient and facile route for quantitative coating of gamma-Fe2O3 nanoparticles with octadecyltrihydrosilane (OTHS, CH3(CH2)(17)SiH3). The presence of C-H stretching (2950-2850 cm(-1)) and bending (1475-1375 cm(-1)) bands, and the absence of peaks at 2150 and 925 cm(-1) (Si-H stretching and bending respectively) confirm the presence of grafted hydrocarbon chains in the irradiated sample, hence the reaction of OTHS with gamma-Fe2O3 nanoparticles. The coated nanoparticles show increased magnetization compared to the uncoated ones. X-ray diffraction, magnetization studies, Mossbauer spectra, and electron paramagnetic resonance spectra reveal that the magnetic ordering is more prominent in the OTHS-coated gamma-Fe2O3 sample because of improved crystallinity.