Tungsten oxide nanowire growth by chemically-induced strain

TL;DR

This study explores the growth of tungsten oxide nanowires via chemical-induced strain during CVD, revealing a new growth mechanism driven by interfacial strain from tungsten carbide formation.

Contribution

It introduces a chemically-driven whisker growth mechanism for tungsten oxide nanowires, potentially applicable to other nanowire systems.

Findings

Nanowires are typically 10 nm in diameter.

Growth occurs at 900°C with hydrogen and methane.

Crystalline WO3 nanowires are formed.

Abstract

We have investigated the formation of tungsten oxide nanowires under different CVD conditions. We find that exposure of oxidized tungsten films to hydrogen and methane at 900C leads to the formation of a dense array of typically 10 nm diameter nanowires. Structural and chemical analysis shows that the wires are crystalline WO3. We propose a chemically-driven whisker growth mechanism in which interfacial strain associated with the formation of tungsten carbide stimulates nanowire growth. This might be a general concept, applicable also in other nanowire systems.