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Title: VO2 thin films and nanoparticles, from chemical vapour deposition and hydrothermal synthesis, for energy efficient applications
Author: Powell, M. J.
ISNI:       0000 0004 7229 4351
Awarding Body: UCL (University College London)
Current Institution: University College London (University of London)
Date of Award: 2015
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Thin films of VO2 were synthesised by atmospheric pressure chemical vapour deposition (APCVD). The effect of deposition time on the thickness of the films was studied. The samples synthesised were the first time monoclinic VO2 has been demonstrated by the reaction between vanadium (IV) chloride and ethyl acetate under APCVD conditions. Multi-layer films of VO2/SiO2/TiO2 were also synthesised by APCVD and the effect on the thermochromism and visible light transmission were investigated. The multi-layered VO2/SiO2/TiO2 is the first such multi-layer to be demonstrated by APCVD. A specialised Fluidised Bed Chemical Vapour Deposition (FBCVD) reactor was designed and built specifically for the project, with this design being utilised to coat powder substrates with thin films of TiO2. A multi-shelled system of anatase on rutile on mica was deposited to demonstrate that the FBCVD system is capable of depositing core-shell and multi-shelled systems with fast and uniform growth rates. The different TiO2 samples were tested for their photocatalytic properties by measuring stearic acid destruction rates. VO2 nanoparticles were synthesised by Continuous Hydrothermal Flow Synthesis (CHFS), with the effect of temperature and residence time within the CHFS reactor on the phase produced and particle size distribution was evaluated. This is the first time that CHFS has been used to produce VO2 nanoparticles. Finally, CHFS was used to synthesise nanoparticles of Nb doped VO2. The effect of varying the concentration of Nb was investigated by evaluating the phase of vanadium oxide synthesised, the range of particle size and the thermochromic properties observed in the material.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available