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Approche des mécanismes de frittage non conventionnel et des propriétés spectroscopiques de céramiques transparentes dopées holmium pour des lasers émettant dans le moyen infrarouge

Abstract : This thesis focuses on the development of transparent ceramics for high power laser applications in the mid-infrared for the medical field and gas detection. The studied compound is lutetium oxide Lu2O3, which exhibits better thermomechanical properties than YAG. The luminescence ion is the Ho3+ ion, with main light emission around 2.1 μm. Lu2O3:Ho ceramic powders are produced by the chemical route of co-precipitation, from commercial oxide powders judiciously chosen for their purity. A calcination study is carried out to determine the best thermal conditions in order to have powders with the most homogeneous particle size, and therefore good sinterability. A study of the effect of the ionic radius of a co-dopant (Sc3+, Y3+, Gd3+) is also carried out, using dilatometric analyzes under vacuum and SPS. A study of the mechanisms of densification by Spark Plasma is performed on a nanoscale powder by using two approaches of the creep equation during pressure-assisted sintering. Knowledge of the evolution of these mechanisms during heat treatment allows the best adaptation of the application of temperature and stress profiles in future tests, thus allowing laser quality samples to be obtained. These transparent samples are studied with transmission measurements and then in photoluminescence spectroscopy in order to highlight the different electronic transitions and possible relaxations at high doping rates. The data obtained for Lu2O3:Ho are compared to YAG:Ho, the current reference material. In parallel, laser gain measurements were performed on YAG: Ho ceramics.
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Submitted on : Tuesday, April 20, 2021 - 11:12:11 AM
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Lucas Viers. Approche des mécanismes de frittage non conventionnel et des propriétés spectroscopiques de céramiques transparentes dopées holmium pour des lasers émettant dans le moyen infrarouge. Matériaux. Université de Limoges, 2021. Français. ⟨NNT : 2021LIMO0012⟩. ⟨tel-03202768⟩

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