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Particle size, morphology, phase transition and energy efficient applications of hydrothermally produced VO2(D)

Teixeira Gomez, Diana C; (2018) Particle size, morphology, phase transition and energy efficient applications of hydrothermally produced VO2(D). Doctoral thesis (Ph.D), UCL (University College London). Green open access

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Abstract

Thin films of thermochromic vanadium(IV) oxide, VO2(M), were synthesized using sol-gel/spin coating techniques and aerosol assisted chemical vapour deposition (AACVD). The effect of precursor solution aging, thickness and annealing temperature was studied. A recently reported vanadium dioxide phase, VO2(D), was studied in this work. Its structure (reported in the literature) is discussed and another possible structure is presented and analyzed in this work. VO2(D) nanoparticles of 20-30 nm were synthesized for the first time using vanadium pentoxide as a precursor via hydrothermal synthesis. The phase transition from VO2(D) to thermochromic VO2(M) was studied and reported to be the lowest phase transition temperature (165 °C) in order to obtain thermochromic VO2. The pH conditions of the starting solution were studied and reported to be a critical and important feature in the reaction. Different morphologies of VO2(D) microparticles were prepared using ammonium metavanadate as a precursor by hydrothermal synthesis. VO2(D) microparticles from 1 to 5 micron in size were reported with star shape, round-ball, elongated particles shape among others at different pH. The effect of the starting pH solution in the final product was studied. Thermochromic VO2(M) microparticles were obtained after mild calcination. Finally, thermochromic polymeric films were prepared using VO2(M) nanoparticles obtained after low temperature calcination of VO2(D) nanoparticles. The nanoparticles were encapsulated into a polyvinylpyrrolidone matrix and deposited via spin coating onto a glass substrate.

Type: Thesis (Doctoral)
Qualification: Ph.D
Title: Particle size, morphology, phase transition and energy efficient applications of hydrothermally produced VO2(D)
Event: UCL (University College London)
Open access status: An open access version is available from UCL Discovery
Language: English
UCL classification: UCL > Provost and Vice Provost Offices
UCL > Provost and Vice Provost Offices > UCL BEAMS
UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences
UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences > Dept of Chemistry
URI: https://discovery.ucl.ac.uk/id/eprint/10056325
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