NANO LETTERS
Tungsten Oxide Nanowires on Tungsten Substrates
2002 Vol. 2, No. 8 849-851
Gang Gu,† Bo Zheng,† W. Q. Han,‡ Siegmar Roth,§ and Jie Liu*,† Department of Chemistry, Duke UniVersity, Durham North Carolina 27708, Department of Physics, UniVersity of California, Berkeley, California 94720-7300, and Max-Planck-Institut fu¨ r Festko¨ rperforschung, Heisenbergstrasse 1, D-70569 Stuttgart, Germany Received May 17, 2002
ABSTRACT A simple method was discovered to prepare tungsten oxide nanowires directly from tungsten metal. The structure and composition of the nanowires were characterized by high resolution tunneling electron microscopy (HRTEM) and energy dispersive X-ray scattering (EDX), respectively. The growth mechanism and potential applications of this material are discussed.
Transition metal oxides are a large family of materials that show many interesting properties such as superconductivity, colossal magnetoresistance, and piezoelectricity. Nanosized transition metal oxides, because of their huge surface areas, are promising candidates for a vast range of applications including lithium-ion batteries1,2 catalysts,3 electrochromic materials,4,5 and sensors.6,7 Moreover, investigation on properties of nanosized metal oxides will shed light on mechanisms of superconductivity and colossal magnetoresistance of these materials. Among transition metal oxides, sodium tungsten bronze NaxWO3 with x ∼ 0.05 was recently reported to be a high-temperature superconductor with Tc ∼ 90 K.8 Before that, Matthias et al. reported superconductivity with Tc ∼ 3-5 K9 for the same material but with a different doping level with 0.1 < x
