Effects of Growth Temperature and Postgrowth Annealing Treatment on Photoluminescence of SnO2 Nanoblades Prepared by Hydrothermal Process

Large-scale SnO2 nanoblades were synthesized by a low-temperature hydrothermal process. The growth rate and degree of crystallinity of the SnO2 nanoblades were found to increase with decreasing growth temperature. An intense blue photoluminescence (PL) centered at 445 nm was observed in all the as-synthesized SnO2 nanoblades. As the growth temperature was decreased from 90 to 80 and 70 degrees C, the PL peak intensity of the SnO2 nanoblades decreased by about 29 and 41%, respectively. Meanwhile, the PL peak intensity would reduce by about 42% and enhance by about 23%, respectively, after oxygen and vacuum annealing at 400 degrees C for 4 h. The zero-crossing g value in the electron paramagnetic resonance spectra was calculated to be 2.0019, implying that there exist many singly ionized oxygen vacancies in our SnO2 nanoblades. The blue luminescence from SnO2 nanoblades can be attributed to the possible recombinations of electrons on singly ionized oxygen vacancies or conduction band and holes on the valence band, tin-oxygen vacancy centers, or doubly ionized oxygen vacancies.