Orientador: Fernando Aparecido Sigoli

Tese (doutorado) - Universidade Estadual de Campinas, Instituto de Química

Resumo: Baseado nas propriedades ópticas e magnéticas dos íons lantanídeos, este trabalho apresenta a síntese e caracterização de nanopartículas de NaTRF4, tipo caroço@casca, dopadas com os íons ErIII, YbIII, DyIII e NdIII, de natureza multifuncional. Para isso, as composições e fases cristalinas do...

Resumo: Baseado nas propriedades ópticas e magnéticas dos íons lantanídeos, este trabalho apresenta a síntese e caracterização de nanopartículas de NaTRF4, tipo caroço@casca, dopadas com os íons ErIII, YbIII, DyIII e NdIII, de natureza multifuncional. Para isso, as composições e fases cristalinas do caroço e das cascas foram controladas de modo a otimizar suas propriedades ópticas e magnéticas. Assim, foi obtido um material em que um caroço contendo DyIII, principal responsável pelas propriedades magnéticas foi revestido por cascas contendo ErIII, YbIII e NdIII ópticas e magneticamente ativas. As nanopartículas foram sintetizadas nas fases cristalinas cúbica, hexagonal e heterogênea, sendo que, o caroço e as cascas podem apresentar fases diferentes, otimizando assim as propriedades dependentes da fase. Os resultados obtidos mostram a formação de nanopartículas cristalinas e com distribuição de tamanhos uniformes. Mapeamentos por EDS, comprovam a estrutura hierárquica dos sistemas caroço@casca, que são também confirmados por estudos sistemáticos de luminescência e magnetização. As nanopartículas que compõe este trabalho, apresentam emissões do tipo upconversion, na região visível do espectro eletromagnético, e downshifting na região do infravermelho próximo, usando com fonte de excitação lasers nos comprimentos de onda de 808, 980 e 1550 nm, em que mais de uma janela de transparência biológica pode ser explorada. Medidas de termometria, monitorando as emissões no visível e no infravermelho próximo, apresentam resultados promissores, com valor máximo de sensibilidade térmica relativa de 2,88 %.K-1 a 633K, em ampla faixa de temperatura (77K a 600K). As emissões upconversion do caroço@casca podem ser modulados por um campo magnético externo, em ao menos uma faixa de 0 a 10T. Resultados surpreendentes de sensibilidade relativa em função do campo magnético foram encontradas (23,9 % T-1 a 7,5T) evidenciando a natureza versátil do caroço@casca e sua potencialidade quanto às aplicações como sondas ópticas de campo magnético e temperatura

Abstract: Based on the optical and magnetic properties of the lanthanide ions, this work presents the synthesis and characterization of NaREF4 multifunctional core@shell nanoparticles, doped with the ions ErIII, YbIII, DyIII e NdIII. For this, core, shell compositions, and crystalline phases were...

Abstract: Based on the optical and magnetic properties of the lanthanide ions, this work presents the synthesis and characterization of NaREF4 multifunctional core@shell nanoparticles, doped with the ions ErIII, YbIII, DyIII e NdIII. For this, core, shell compositions, and crystalline phases were controlled to optimize their optical and magnetic properties. Therefore, a cubic core containing DyIII ion was obtained, mainly responsible for magnetic properties. On the other hand, the shells active are optically and magnetically from the ErIII, YbIII, and NdIII ions distributed. The nanoparticles were prepared in cubic, hexagonal and heterogeneous crystalline phases, where the core and shells may present different phases, thus optimizing phase-dependent properties. The results show the formation of high crystallinity and narrow size nanoparticles. The core@shell systems hierarchy was confirmed by EDS mapping and luminescence and systematic magnetization study. The nanoparticles that compose this work emits in the visible region (upconversion) and the NIR (downshifting) after excitation at 808, 980, and 1550 nm covering more than one biological window. Thermometry measurements were monitored by the visible region and NIR, revealing promising results, with a maximum thermal sensitivity of 2.88% K-1 to 633K, in a wide temperature range (77K to 600K). Studies of upconversion emission for core@shell nanoparticles were modulated by applying an external magnetic field in 0 to 10T. Excellent results for the relative sensitivity as to the function of the magnetic field were found of 23.9% T-1 at 7.5T, indicating the versatile nature of core@shell and their applicability as an optical probe of magnetic field and temperature.Based on the optical and magnetic properties of the lanthanide ions, this work presents the synthesis and characterization of NaREF4 multifunctional core@shell nanoparticles, doped with the ions ErIII, YbIII, DyIII e NdIII. For this, core, shell compositions, and crystalline phases were controlled to optimize their optical and magnetic properties. Therefore, a cubic core containing DyIII ion was obtained, mainly responsible for magnetic properties. On the other hand, the shells active are optically and magnetically from the ErIII, YbIII, and NdIII ions distributed. The nanoparticles were prepared in cubic, hexagonal and heterogeneous crystalline phases, where the core and shells may present different phases, thus optimizing phase-dependent properties. The results show the formation of high crystallinity and narrow size nanoparticles. The core@shell systems hierarchy was confirmed by EDS mapping and luminescence and systematic magnetization study. The nanoparticles that compose this work emits in the visible region (upconversion) and the NIR (downshifting) after excitation at 808, 980, and 1550 nm covering more than one biological window. Thermometry measurements were monitored by the visible region and NIR, revealing promising results, with a maximum thermal sensitivity of 2.88% K-1 to 633K, in a wide temperature range (77K to 600K). Studies of upconversion emission for core@shell nanoparticles were modulated by applying an external magnetic field in 0 to 10T. Excellent results for the relative sensitivity as to the function of the magnetic field were found of 23.9% T-1 at 7.5T, indicating the versatile nature of core@shell and their applicability as an optical probe of magnetic field and temperature

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