Growth and lattice dynamics of single-crystalline SnO2 nanowires prepared by annealing a gel precursor

A large amount of ultra-long single-crystalline SnO2 nanowires were successfully synthesized through a polymeric sol–gel approach followed by a post-annealing in a crucible covered with a lid. The experimental results indicate that the product is composed of tetragonal SnO2 nanowires, and moreover, their growth mechanism should arise from the self-catalyzed Sn-terminated polar surfaces due to the enrichment of Sn at the growth front of nanowires. In Raman scattering spectrum, in addition to three fundamental vibrational modes, some infrared (IR) active and surface phonon modes (SPM) are also observed due to size and shape confinement effects and surface disorder. Similarly, low frequency non-active IR and surface phonon mode absorptions are also observed in IR spectra.