Fósforos à base de diopsita (CaMgSi2O6) dopada com disprósio (Dy3+) foram preparados a partir da combinação dos métodos sol-gel e coprecipitação. Foram adotados três procedimentos diferentes para síntese, nos quais gel de sílica foi obtido a partir de solução de Na2SiO3 e a ele foi adicionado precipitados de hidróxidos de cálcio, magnésio e disprósio. A etapa de lavagem da mistura dos precipitados foi estudada para evitar dissolução dos hidróxidos de cálcio e magnésio. O produto lavado, após calcinação a 900°C por períodos de 1 a 3 horas, foi obtido o pó cerâmico apresentando diopsita como fase principal, confirmada por análise de DRX. O espectro de emissão de fotoluminescência do pó cerâmico apresentou os picos característicos do Dy3+, localizados nas regiões do azul e do amarelo. A partir da relação entre as intensidades desses picos, é possível obter luz branca. Foram variadas as concentrações de dopagem de disprósio nas amostras. Aquelas com concentrações de até 0,5%mol em disprósio foram as que apresentaram emissões mais próximas do branco, segundo o diagrama CIE. Foi observado um comportamento interessante da relação entre a luminescência em função do teor de dopagem de disprósio. Verificou-se que o aumento do teor de disprósio acarreta diminuição da intensidade de emissão até certo ponto onde ela volta a aumentar. As curvas de persistência luminescente apresentaram decaimento da ordem de décimos de segundos, o que pode indicar que o material não apresenta defeitos em quantidade ou profundidade suficiente para aplicações como fósforo persistente. / Dy-doped diopside (CaMgSi2O6) based phosphors were prepared by combining sol-gel and coprecipitation methods, using three different routes. Silica gel was obtained from aqueous Na2SiO3 solution, and then hydroxide precipitates of calcium, magnesium and dysprosium were added to the gel. The washing process of the mixture of precipitates step was studied to avoid dissolution of calcium and magnesium hydroxides. The washed product, after calcining at 900° C for periods of 1 to 3 hours, a ceramic powder showing diopside as main crystalline phase was reached, confirmed by XRD analysis. The emission spectrum of photoluminescence of ceramic powder presented the characteristic peaks of Dy3+, located in the regions of blue and yellow. From the relationship between the intensities of these peaks, white light can be obtained. The concentration of dysprosium was varied in the samples. Those with concentrations of up to 0.5% in dysprosium were those which presented the white emissions, according to the CIE diagram. Interesting behavior was observed relation between luminescence and of dysprosium doping content in the samples. It was found that by increasing the content of dysprosium, the emission intensity decreased to a point where it back to increasing. Persistence luminescent curves presented very fast decay, of tenths of seconds, which may indicate that the material does not present defects in quantity or enough depth for applications such as persistent phosphors.

Novel lanthanide phthalocyanines containing dysprosium, erbium and lutetium as central metals were synthesized using phthalonitrile:metal salt ratio of 4:1 or lower phthalonitrile content as well as using unmetallated phthalocyanine. They were characterized using various spectroscopic and elemental analyses. Dysprosium bis-phthalocyanine was obtained while monomers were obtained for erbium and lutetium phthalocyanines. Theopen-shelldysprosiumbis-phthalocyanine and the monomeric complex of the open-shell erbium were neither fluorescent nor showed the ability to generate singlet oxygen. The triplet states of all the lutetium phthalocyanines were found to be populated with high triplet quantum yields and corresponding high singlet oxygen quantum yields. The fluorescence quantum yields of the lutetium phthalocyanines were however found to be very low. The lutetium phthalocyanines together with unsubstituted zinc phthalocyanine and its derivatives were successfully incorporated into electrospun polymer fibers either by covalent linkage or sorption forces. Spectral characteristics of the functionalized electrospun polymer fibers indicated that the phthalocyanines were bound and their integrity maintained within the fiber matrices. Most importantly the fluorescence and photoactivity of the phthalocyanines were equally maintained within the electrospun fibers. The functionalized electrospun polymer fibers especially those containing the zinc phthalocyanines could qualitatively detect nitrogen dioxide, a known environmental air pollutant. Also all the functionalized electrospun polystyrene and polysulfone fibers containing lutetium and zinc phthalocyanines could be applied for the photoconversion of 4-chlorophenol, 4-nitrophenol and methyl orange. Those of polystyrene could be re-used. Polyacrylic acid and polyurethane functionalized electrospun fibers were found not to be suitable for photocatalytic applications in aqueous medium. 4-Chlorophenol was found to be more susceptible to photodegradation while methyl orange very difficult to degrade.

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Dans ce travail de thèse, je présente la construction d’une nouvelle expérience pour la production de gaz ultra froids de dysprosium. En tirant parti de la structure électronique à couche incomplète de ces atomes, nous visons à la réalisation de champs de jauge synthétiques, qui pourront conduire à l’observation de nouvelles phases (topologiques) de la matière. Le couplage du spin atomique avec le champ lumineux, plus efficace que pour des atomes alcalins, permettra d’atteindre des régimes d’interactions fortes qui restent, jusqu’à présent, hors de portée expérimentale. J’adapte des protocoles existants pour la réalisation de champs de jauge dans le cas de Dysprosium, en tenant compte de son grand spin électronique (J = 8 dans l’état fondamental). En outre, le dysprosium a le plus grand moment magnétique parmi les éléments stables, et il est donc le meilleur candidat pour l’étude des gaz dipolaires. Je détaille le dispositif expérimental que nous avons construit et comment nous effectuons le piégeage et le refroidissement du dysprosium. Nous étudions en détail le comportement du piège magnéto-optique, qui est réalisé sur la transition d’intercombinaison ¹S₀ ↔ ³P₁. La raie étroite et le grand spin rendent l’opération du piège très complexe. Néanmoins, je montre que sa compréhension devient assez simple dans le régime où le nuage se polarise spontanément en conséquence de la combinaison des forces optiques et gravitationnelles. Enfin, je décris les dernières étapes du transport optique et de l’évaporation, ce qui conduira à la production d’un gaz dégénéré. / In this thesis I present the construction of a new experiment producing ultra cold gases of Dysprosium. Using the favourable electronic structure of open-shell lanthanide atoms, we aim at the realisation of laser-induced synthetic gauge fields, which could lead to the observation of novel (topological) phases of matter. The coupling of the atomic spin with the light field, improved with respect to alkali atoms, opens the possibility to explore strongly interacting regimes that were up to now out of experimental reach. I adapt existing protocols for the implementation of gauge fields to the case of Dysprosium, taking into account its large electronic spin (J = 8 in the ground state). Moreover, Dysprosium has the largest magnetic moment among the stable elements, and is the best candidate for the study of dipolar gases. I describe the experimental setup that we built and how we perform the trapping and cooling of Dysprosium. We study in detail the behaviour of the magneto-optical trap, which is performed on the ¹S₀ ↔ ³P₁ intercombination line. The narrow linewidth and the large spin make the trap operation quite challenging. Nevertheless, I show that its understanding becomes quite simple in the regime where the cloud spontaneously polarises due to the interplay of optical and gravitational forces. Finally, I describe the last steps of optical transport and evaporation, which will lead to the production of a degenerate gas.