Unveiling low-temperature thermal oxidation growth of W18O49 nanowires with metastable β-W films

investigated for both W films and powders. W18O49 nanowires could be steadily obtained with appropriate temperature and oxygen pressure ranges for both cases, while the growth temperature of a W film (metastable β phase dominant) could be much lower than that of W powder (α phase). The structural analysis indicates that metastable β-W is susceptible to oxidation in comparison with α-W and thus generates oxidation-induced chemical compression for nanowire growth. The growth temperature of W18O49 nanowires could be reduced to ca. 400 °C, which paves the way for the in situ patterning of W18O49 nanowires on indium-tin-oxide (ITO) glass substrates and flexible substrates.