Grain boundary effect on structural, optical, and electrical properties of sol-gel synthesized Fe-doped SnO2 nanoparticles

Tin oxide (SnO2) and iron-doped tin oxide (Sn1 - x Fe x O2, x = 0.05 wt%, 0.10 wt%) nanoparticles are synthesized by the simple sol-gel method. The structural characterization using x-ray diffraction (XRD) confirms tetragonal rutile phases of the nanoparticles. The variations in lattice parameters and relative intensity with Fe-doping concentration validate the incorporation of iron into the lattice. The compressive strain present in the lattice estimated by using peak profile analysis through using Williamson-Hall plot also exhibits the influence of grain boundary formation in the lattice. The radiative recombination and quenching observed in optical characterization by using photoluminescence spectrum (PL) and the shift in the band gap estimated from UV-visible diffused reflectance spectrum corroborate the grain boundary influence. Raman spectrum and the morphological analysis by using a field emission scanning electron microscope (FESEM) also indicate the formation of grain boundaries. The compositional analysis by using energy dispersive x-ray spectrum (EDAX) confirms Fe in the SnO2 lattice. The conductivity studies exhibit that the impendence increases with doping concentration increasing and the loss factor decreases at high frequencies with doping concentration increasing, which makes the Sn1 - x Fe x O2 a potential candidate for device applications.