Magnetic Enhancement of γ-Fe₂O₃ Nanoparticles by Sonochemical Coating

We show that sonochemistry is an efficient and facile route for quantitative coating of γ-Fe 2 O 3 nanoparticles with octadecyltrihydrosilane (OTHS, CH 3 (CH 2 ) 17 SiH 3 ). 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 γ-Fe 2 O 3 nanoparticles. The coated nanoparticles show increased magnetization compared to the uncoated ones. X-ray diffraction, magnetization studies, Mössbauer spectra, and electron paramagnetic resonance spectra reveal that the magnetic ordering is more prominent in the OTHS-coated γ-Fe 2 O 3 sample because of improved crystallinity.