Synthesis, photoluminescence and dielectric properties of O-deficient SnO2 nanowires

High-quality rutile SnO2 nanowires were fabricated by a vapor-phase transport and condensation method assisted by carbothermal reduction. The composition and structure were investigated in detail. It is found that many oxygen vacancies exist in the single-crystalline rutile SnO2 nanowires and can further influence the photoluminescence (PL) and dielectric property of the nanowires. The PL spectrum only exhibits a wide yellow emission centered at 570 nm and usual near band edge emission is not observed, which is ascribed to a large amount of ionized oxygen vacancies. The dielectric measurements indicate that the dielectric response of the SnO2 nanowires is significantly enhanced in the low-frequency range. It is thought both the rotation direction polarization (RDP) and the space charge polarization (SCP) process induced by O vacancies and nanosize effects are the main reasons for the enhancement of relative dielectric constant (ɛr) of these SnO2 nanowires.