Effect of iron doping on ESR and Raman spectra of SnO₂ nanomaterials

Iron doped tin oxide magnetic semiconductor nanoparticles, Sn_1-xFe_xO₂ with x = 0.0, 0.1, 0.2, and 0.3% were prepared by the sol-gel method. The X-ray diffraction patterns for all samples display the rutile SnO₂ structure with no impurity peaks. At room temperature, electron spin resonance (ESR) spectra characteristic to Fe³⁺ was observed in all samples with broad and small intensity peaks. The shift of the ESR signal to lower fields and the change in the line width are attributed to the anisotropy in the non-spherical particles and to the enhanced dipolar magnetic interactions with Fe³⁺ concentrations. The Raman spectrum of pure and Fe doped SnO₂ nanoparticles was found to be of the rutile phase structure (Eg, A_1g, and B_2g). The characteristic, active modes at 320 and 690 cm^-1 appeared in Raman spectrum, in some cases the bands were broadened in due to variable laser power sources. The broadening of the Eg mode is attributed to oxygen vacancies and nanosize effects.