Propriedades de termoluminescência e luminescência opticamente estimulada do KMgF3 não dopado e dopado com terras raras

• Ano de defesa: 2022
• Autor(a) principal: Cruz, Jonathan Uendler Oliveira
• Orientador(a): Macedo, Zélia Soares
• Tipo de documento: Dissertação
• Tipo de acesso: Acesso aberto
• Idioma: por
• Programa de Pós-Graduação: Pós-Graduação em Física
• Palavras-chave em Português: termoluminescência; Luminescência opticamente estimulada; Fluoreto de potássio e magnésio (KMgF3); Terras raras
• Palavras-chave em Inglês: Thermoluminescence; Optically stimulated luminescence
• Área do conhecimento CNPq: CIENCIAS EXATAS E DA TERRA::FISICA
• Link de acesso: https://ri.ufs.br/jspui/handle/riufs/18848

The use of techniques such as optically stimulated luminescence (OSL) and thermoluminescence (TL) in the investigation of materials for applications such as radiation detectors and in the study of defects in solids has stimulated the study of luminescent materials with a wide range of properties. In the literature, it is reported that materials such as Al2O3:C and NaMgF3:Eu2+ have applications as dosimeters. Potassium magnesium fluoride (KMgF3) is a material that has high OSL sensitivity and TL peaks above 200 °C, with low fading and potential applicability in ionizing radiation dosimetry. Studies have shown that KMgF3 when doped with Ce ions has an OSL sensitivity comparable with Al2O3:C, while KMgF3 when doped with Eu ions and annealed at 800°C for 1h has a TL sensitivity comparable to LiF:Mg,Ti, and OSL comparable to Al2O3:C. Thus, in this work, we sought to investigate the TL and OSL properties of KMgF3 undoped and doped with rare earth ions (Eu, Ce and Tb), in addition to the effect of heat treatment on the luminescent sensitivity of the material. The synthesis method used was microwave-assisted hydrothermal, previously synthesized samples were used. The experimental realization of this work took place from the production of pellets and subsequent heat treatment, in addition to the use of techniques such as TL, OSL and radioluminescence (RL). The study of the influence of the heat treatment process on the sensitivity of TL emission was carried out at different temperatures (600°C, 700°C and 800°C) for 1h, 2h, 3h and 4h in an oven. The TL results showed that the annealing process at 800ºC for 1 hour favored the TL sensitivity by at least 90% compared with the as prepared sample, considering the total area. This suggests that heat treatment increases the density of defects that contribute to the TL emission of the material. Furthermore, the results showed that the samples of KMgF3, KMgF3:Eu and KMgF3:Ce present TL peaks in a range suitable for dosimetry applications. TL measurements also show that the material has no shallow traps. The RL emission spectra show that the signal is related to Ln3+ dopants and intrinsic defects induced by the sintering process. Trap depths were calculated using the multirate method and fitting the brightness curves using a first-order kinetics model. OSL measurements were performed for all samples, but only samples of KMgF3 doped with Eu and Ce showed emission.