Title: Synthesis of tungsten oxide nanostructures by laser pyrolysis

Authors: Bonex Wakufwa Mwakikunga, Andrew Forbes, Elias Sideras-Haddad, Rudolph Marthinus Erasmus, Gift Katumba, Bathusile Masina

Addresses: School of Physics, University of the Witwatersrand, Private Bag 3, PO Wits 2050, Johannesburg, South Africa; CSIR National Centre for Nano-Structured Materials, P.O. Box 395, Pretoria 0001, South Africa; Department of Physics and Biochemical Sciences, University of Malawi, Private Bag 303, Chichiri, Blantyre 3, Malawi. ' Council for Scientific and Industrial Research, National Laser Centre, P.O. Box 395, Pretoria 0001, South Africa; School of Physics, University of Kwazulu-Natal, Private Bag X54001, Durban 4000, South Africa. ' School of Physics, University of the Witwatersrand, Private Bag 3, PO Wits 2050, Johannesburg, South Africa. ' School of Physics, University of the Witwatersrand, Private Bag 3, PO Wits 2050, Johannesburg, South Africa. ' Department of Physics, University of Zimbabwe, P.O. Box MP 167, Mt Pleasant, Harare, Zimbabwe; CSIR National Laser Centre, P.O. Box 395, Pretoria, South Africa. ' Council for Scientific and Industrial Research, National Laser Centre, P.O. Box 395, Pretoria 0001, South Africa; Department of Physics, University of Zululand, Private Bag X1001, Kwadlangezwa 3886, South Africa

Abstract: Since the proposal to synthesise materials by laser assisted pyrolysis in the 1970s, and its practical realisation in 1982, a number of researchers have used this method in obtaining nano-powders from liquid droplets. This study revisits this technique by introducing a new aspect in that it considers obtaining thin films rather than powders. A full experimental arrangement, including laser optimisation, optical layout and materials processing procedures is described. Synthesis of WO₃ nanostructures by this method is reported for the first time, with the mean diameter and length determined to be 51 nm and 6.8 µm, respectively. A possible mechanism for production of such nanostructures is proposed owing to the selective dissociation of the O-C bonds in the tungsten ethoxide precursor liquid which resonate with the 10.6 µm emission wavelength of the CO₂ laser employed.

Keywords: WO₃ nanostructures; nanorods; laser pyrolysis; multiphoton dissociation; laser beam propagation; tungsten oxide nanostructures; thin films; nanoparticles.

DOI: 10.1504/IJNP.2008.020895

International Journal of Nanoparticles, 2008 Vol.1 No.3, pp.185 - 202

Published online: 23 Oct 2008 *

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