Synthesis And Optical Properties Of SnO₂ Micro-/Nanomaterials

SnO2 nanospheres, nanocubes and SnO2/Y2O3, SnO2/TiO2 micro-/nano multi-oxide have been synthesized via simple and facile methods. The structures and optical properties of as-prepared products were thoroughly characterized using X-ray diffraction (XRD), thermogravimetry-differential thermal analysis (TG-DTA), Brunner-Emmett-Teller (BET) method, scanning electron microscope (SEM), transmission electron microscope (TEM), high-resolution transmission electron microscope (HRTEM), UV-Vis spectra, NIR spectra respectively. The results are summarized as follows.We have prepared different shaped and sized SnO2 nanoparticles through a simple sol–gel method by different alkaline. SnO2 nanoparticles in the ultraviolet region have a strong absorption band. With the enhancement of crystal size, nanoparticles absorption edge occurred red shift. In the visible and near infrared region they have high reflectance. As the temperature increased, the particle size is increasing, and reducing its scattering coefficient. These all cause the decreasement of diffuse reflectance.And using NH4OH as precipitant we got the smallest particle size and the best dispersion nanospheres along with the highest reflectance, which has the most reflected boundaries and the most scattering coefficient.We have studied the impact factors of the the optical properties of SnO2/Y2O3 multi-oxide. The electronic (hole) concerntration of semiconductor have been changed by Y ion doped or Y2O3 recombinated which improved its near-infrared reflectance. With the enhacement of the concentration of Y ion or the content of Y2O3, the band gap of semiconductor increased and the free carrier concentration of compound semiconductor material reduced. Reducing its carrier absorption in the infrared region is in order to increase the reflectance of near infrared and thermal insulation capacity.We have prepared different molar ratio of SnO2/TiO2 precursor by sol-gel method, and after 500 ?C calcined got different content rutile TiO2 of SnO2/TiO2 nano-particles. And we also reduced the phase transition temperature of rutile TiO2 by 150 ?C. With the increasing content of rutile TiO2, the absorption increased in the ultraviolet region. We also researched the best molar ratio and got 83% rutile TiO2 crystal of the SnO2/TiO2 nano particles under 500 ?C which has the similar high reflect with the rutile TiO2 in near-infrared region.