Synthesis of Tungsten Oxide Nanoslab Bundles by Microwave Plasma-Enhanced Chemical Vapor Deposition

Abstract

A large quantity of tungsten oxide nanoslabs was synthesized within 4 min by microwave plasma-enhanced chemical vapor deposition (MPECVD). The structural, geometrical, and chemical compositions of these nanoslabs were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), energy-dispersive X-ray spectroscopy (EDS), and Raman spectroscopy. The results of these characterizations confirmed that the nanoslabs with [010] as the major growth direction have a W(18)O(49) structure with thicknesses of 30-50 nm, widths of up to 300-500 nm, and, lengths of up to 800-2000 nm. In XRD spectra, the reflection peaks are representative of monoclinic W(18)O(49). A vapor-solid (VS) mechanism was confirmed for this growth process because no catalyst was used in this growth process. (C) 2011 The Japan Society of Applied Physics