Synthesis and characteristics of Fe3+-doped SnO2 nanoparticles via sol–gel-calcination or sol–gel-hydrothermal route

Fe3+-doped SnO2 nanoparticles were prepared by sol–gel-calcination and sol–gel-hydrothermal routes, respectively, and their microstructure as well as physical and chemical properties have been characterized and compared. Based on XRD, TEM, and Fourier transform infrared (FT-IR) analyses, the SnO2 crystallites with the tetragonal rutile structure formed directly during a hydrothermal process. Compared with the sol–gel-calcination route, sol–gel-hydrothermal route led to better dispersed nanoparticles with a narrower size distribution and a larger Brunauer–Emmett–Teller (BET) surface area. Also, the Fe3+-doped SnO2 nanoparticles prepared by sol–gel-hydrothermal route had a better thermal stability against agglomeration and crystalline grain size growth than those prepared by the sol–gel-calcination route. XRD, EDS, and diffuse reflectance spectra (DRS) analyses proved that the Fe3+ and SnO2 formed a solid solution in the nanoparticles with both processing routes. A significant red shift in the UV absorbing band edge was observed with the increasing Fe3+ content.