Thermal evaporation growth and the luminescence property of TiO 2 nanowires

Abstract

Single crystalline TiO 2 nanowires have been successfully grown on alumina substrates using a high-frequency (350 KHz) dielectric heater at 1050 °C by a two-step of thermal evaporation method without using any catalyst. The first step is to form the high surface energy TiO 2 seeds on the low surface energy alumina substrates. The second step is to grow the single crystalline TiO 2 nanowires on the alumina substrates by the vapor–solid (VS) mechanism. The field emission electron microscopy (FESEM) image showed a uniform diameter of 60–90 nm and length of hundreds of nm to 2 μm for the TiO 2 nanowires. The high-resolution transmission electron microscopy (HRTEM) image showed that the TiO 2 nanowires are of single crystalline rutile structure. The luminescence properties were investigated by cathodoluminescence (CL) in FESEM. The result is surprising in that the TiO 2 nanowires are of rutile phase, but the luminescence properties similar to the bulk TiO 2 of anatase phase.