Estudos de materiais dopados com íons lantanídeos para aplicações em nanotermometria

• Ano de defesa: 2023
• Autor(a) principal: Silva, Daniel Lopo da
• Orientador(a): Maia, Lauro June Queiroz
• Banca de defesa: Maia, Lauro June Queiroz, Poirier, Gaël Yves, Santana, Ricardo Costa de
• Tipo de documento: Dissertação
• Tipo de acesso: Acesso aberto
• Idioma: por
• Instituição de defesa: Universidade Federal de Goiás
• Programa de Pós-Graduação: Programa de Pós-graduação em Fisica (IF)
• Departamento: Instituto de Física - IF (RMG)
• País: Brasil
• Palavras-chave em Português: Nanotermometria; Íons lantanídeos; Matrizes oxidas; Sensibilidade térmica
• Palavras-chave em Inglês: Nanothermometry; Lanthanide ions; Oxide matrices; Thermal sensitivity
• Área do conhecimento CNPq: CIENCIAS EXATAS E DA TERRA::FISICA::AREAS CLASSICAS DE FENOMENOLOGIA E SUAS APLICACOES::TRANSFERENCIA DE CALOR; PROCESSOS TERMICOS E TERMODINAMICOS
• Link de acesso: http://repositorio.bc.ufg.br/tede/handle/tede/13225

Optical phenomena such as luminescence of materials depend on several characteristics such as temperature, dopants, crystalline structure, etc. Electromagnetic emissions from materials doped with rare-earth ions can provide thermal information regarding the environment where these materials are inserted. Materials with good thermal sensitivity are considered promising for the development of technologies for nanoscale temperature measurements. In this work, nine samples previously prepared through different synthesis routes such as sol-gel process and modified Pechini were analyzed. The samples studied have matrices of several compounds such as aluminum borates (Al4B2O9) monophasic and embedded in silica, aluminum germanates (Al6Ge2O13) monophasic and embedded in silica, yttrium borates (YBO3) and yttrium aluminum silicates (YAS). Altogether, five trivalent lanthanide ions were used as dopants of the samples: Nd, Eu, Er, Tb and Yb. The emission spectra of the samples were analyzed at seven different temperatures from 25 °C to 55 °C with a variation of 5 °C. Diffuse reflectance spectra were studied to confirm the presence of ions in the matrix and enable the calculation of the energy gap for each sample. From the emission spectrum, photoluminescent intensity ratios (RIFs) were calculated for the calculation of relative thermal sensitivities. The sample that showed the highest value for relative thermal sensitivity (Sr) was the one with the composition YBO3 : Nd3+, Eu3+, Er3+, Yb3+, Tb3+ synthesized at 900°C, presenting a value of Sr = (1,52 ± 0,20) %.K-1 in the temperature range of 35°C and 55°C.