WO3-x nanorods synthesized on a thermal hot plate

Abstract

A simple thermal vapor deposition technique to synthesize crystalline tungsten oxide nanorods in ambient condition is presented. Using a commercial thermal hot plate, a pure 99.9% tungsten foil is heated at 485 ± 5°C under ambient conditions with a piece of 150 μm thick glass cover slide pressing on the tungsten foil. Single crystalline WO3-x nanorods, with a preferential growth axis in the [001] direction, are found to deposit on the cover slide facing the heated tungsten foil. The structure, morphology, and composition of the WO3-x nanorods were characterized using the scanning electron microscopy, transmission electron microscopy, energy dispersive spectrometry, Raman spectroscopy, and X-ray diffraction. In addition, mechanical properties of the as-synthesized nanorods were investigated by employing the three-point bend test using an atomic force microscope. The elastic modulus of the nanorods was found to be in the 10-110 GPa range, and it increases with decreasing diameter of the nanorods. The tungsten oxide nanorod was also found to be a good field emitter with a field enhancement factor estimated to be 9.8 × 104 cm-1. © 2007 American Chemical Society.