Synthesis of Tungsten Oxide Nanostructures by Laser Pyrolysis

Abstract

This dissertation discusses the synthesis method known as laser pyrolysis. The theory on laser pyrolysis has been inferred since 1975, but it is insufficient in predicting the products that can be formed. This is due to the use of a laser, which leads to indecisive reaction pathways from precursor to product. In this work, the laser wavelength and power are varied to initiate a starting point in understanding the complex nature of the laser–precursor interaction, in addition to studying the resulting nanomaterial that is formed by the corresponding laser pyrolysis parameters. The results are justified based on linear and nonlinear optical processes, as well as photophysical and photochemical processes. Experiments to produce tungsten trioxide nanowires were conducted, but similar products could not be achieved, due to the difficulty in emulating ‘sensitive’ variables such as gas pressure and flow rates. However, it was discovered for the first time using this method that six-sided tungsten oxide “stars” can be grown.