Production et caractérisation de nanoparticules de Ti3+: Al2O3 par ablation laser
|Abstract:||Pulsed laser ablation is a well-known technique for the production of nanoparticles that possess the same composition and properties as of the original material. Most of the experiments are done by focusing UV laser pulses on the surface of a monoatomic metallic or semiconductor targets. The technique presented in this work focuses on the use of femtosecond laser pulses to initiate the ablation of titanium doped sapphire, Ti3+: Al2O3 or Ti:sapphire. Ti:sapphire is a well-known laser gain medium, commonly used in femtosecond oscillators or amplificators. In the course of this thesis, pulsed laser ablation of Ti: sapphire and nanoparticle production were made possible by the use of two different methods. The first experiments took place in a vacuum chamber under constant pressure. The second setup used a flow of low pressure helium gas to transport the particles in a high temperature environment before they were collected. SEM and TEM observations lead to the conclusion that the produced particles and particle agglomerates were between 5 and 200 nm in diameter, with a few larger particles. Particles produced in a fixed pressure seem amorphous and their fluorescence spectra are generally blue-shifted. Particles that were passed in the high temperature volume seem to have undergone better crystallization and their spectra are closer to the spectrum of bulk Ti: sapphire. Cr3+: Al2O3 (ruby) nanoparticles were also produced with the low temperature nitrate combustion synthesis method. These experiments produced large quantities of highly agglomerated nanoparticles with very strong fluorescent properties. The fluorescent properties are similar of those of bulk ruby.|
|Document Type:||Mémoire de maîtrise|
|Open Access Date:||19 April 2018|
|Collection:||Thèses et mémoires|
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