Tree-like SnO2 nanowires and optical properties

Tree-like SnO2 nanowires have been grown by a vapor–solid process using a milled SnO2 powder as the evaporation source. Phase, structural evolution and chemical composition were investigated using X-ray diffraction (XRD), X-ray spectrometry (EDS), and scanning electron microscopy (SEM). The process yields a large proportion of ultra-long rutile nanowires of 50–150 nm diameter and lengths up to several tens of micrometers. High-resolution transmission electron microscopy (HRTEM) shows that the SnO2 nanowires are single crystals in the (1 0 1) growth direction with scattered smaller crystals or nanowires as the tree branches. The SnO2 nanostructures were also examined using Fourier transform infra-red (FT-IR) and photoluminescence (PL) spectroscopy. A strong emission band centered at 548 nm dominated the PL spectrum of the tree-like nanowires.