Catalyst-Free Synthesis and Properties of Oxygen-Vacancy-Rich Tungsten Oxide Nanowires

Abstract

In this work, oxygen-vacancy-rich tungsten oxide nanowires were synthesized on Si via grain-by-grain thermal evaporation method without any catalyst; also, WO3-x nanowires were grown on W foils as comparison on their physical properties. High-resolution transmission electron microscopy studies show that the lattice arrays of oxygen-vacancy-rich tungsten oxide nanowires grown on Si were crystalline, while those of WO3-x nanowires grown on W foils were improved in terms of crystallization with increase of growth temperature. We demonstrated this result with x-ray diffraction analysis as well. For physical property measurements, the oxygen-vacancy-rich nanowire grown on Si had a very low resistivity of 4.55 x 10-3 Ω ‧ cm, while the resistivity of WO3-x nanowires grown on W foils decreased as the growth temperature rises. Additionally, we found that WO3-x nanowires exhibit different magnetic properties depending on the valence state of tungsten. Notably, the oxygen-vacancy-rich tungsten oxide nanowires grown on Si possessed special antiferromagnetic properties.