In situ Observation of the Growth of Tungsten Oxide Nanostructures

Abstract

This paper describes a method for producing tungsten oxide nanostructues in an environmental scanning electron microscope. The growth is observed in real time and offers direct observation of the morphology of the tungsten oxide condensed onto the cooler part of a typical W scanning electron microscope filament. We also find that the growth of nanostructures Occurs on timescales much shorter than reported thus far. Corresponding to increasing temperatures along the tungsten filament, we find that the tungsten oxide deposits successively as nano-clusters, nano-multirods, 'pine-tree'-like structures and, ultimately, single nanowires.