À rede Nanofoton e ao Instituto Nacional de Fotônica, ambos do CNPq pela compra de reagentes e equipamentos necessários para as medidas de luminescência.Aos amigos que ainda estão e aos que passaram pelo laboratório pela amizade e apoio em todos os momentos.À minha família, especialmente aos meus pais, por terem me proporcionado o aprendizado, amizade e, sobretudo, o amor. À todos os que, de alguma forma, foram importantes para a realização deste trabalho.
ABSTRACTThis work presents a spectroscopic study about Eu 3+ , Nd 3+ and Er 3+ rare-earth doped germanate glasses containing metallic and semiconductor nanoparticles (NPs) aiming the development of new materials for photonic applications. These glasses have a large transmission window (400-4500 nm), high refractive index (~1.9), low phonon energy (700 cm -1 ), high mechanic resistance and chemical durability. Transmission Electronic Microscopy analysis was performed to verify the metallic and semiconductor NPs nucleation, and indicated the presence of metallic and semiconductor NPs. X ray fluorescence by energy dispersive spectroscopic (EDS) and electron diffraction analysis showed the chemical nature of the NPs. Optic absorption measurement proved the trivalent incorporation of the rare-earth ions, the responsible phenomenon for the luminescence of the glasses that allowed the measurement of the absorption bands related to the superficial plasmon resonance. Emission measurements were performed with different procedures, related to nature of the rare-earth. observed in the samples containing silver, gold, and silver together with gold NPs. For the samples containing silicon NPs it was observed a considerable enhancement of the frequency upconversion emission of the erbium. The luminescence enhancement of the samples with metallic NPs is due to the enhancement of the local field nearby the rare-earth ions and/or to the energy transfer between the NPs and the rare-earth ions. The luminescence enhancement of the samples with semiconductor NPs are due to the efficient energy transfer between the NPs and the rare-earth ions originated from the excitons recombination inside the semiconductor NPs. Therefore, the presence of the NPs plays an important role on the luminescence enhancement, allowing de development of new materials for nanophotonic applications.Keywords: metallic nanoparticles, semiconductor nanoparticles, rare-earth ions, europium, erbium, neodymium, germanate glasses. Este material exibe uma transição onde a fase amorfa possui uma descontinuidade nas propriedades termodinâmicas derivativas [33]. Essa transição é comumente chamada de 'transição vítrea' e decorre de resfriamento rápido do material em fase líquida, de modo que ele passe para fase sólida sem que haja tempo de o material cristalizar-se. Durante o processo de resfriamento rápido do material em fase líquida, a temperatura e o volume devem decrescer quase que continuamente. Caso ocorra descontinuidade na queda da temperatura na região da temperatura de cristalização (T c ), como mostra a figu...