DSpace Community:https://repositorio.ufu.br/handle/123456789/51662026-09-22T04:20:49Z2026-09-22T04:20:49ZFundamentos e práticas da medicina nuclear: radiofármacos, controle de qualidade e radioproteçãohttps://repositorio.ufu.br/handle/123456789/503612026-09-21T18:54:55Z2026-08-05T00:00:00ZTitle: Fundamentos e práticas da medicina nuclear: radiofármacos, controle de qualidade e radioproteção2026-08-05T00:00:00ZTermometria óptica em vidros fosfatos dopados com Sm3+ e Ho3+: transferência de energia e modelo LIR de múltiplos processoshttps://repositorio.ufu.br/handle/123456789/502832026-09-16T06:21:38Z2026-07-27T00:00:00ZTitle: Termometria óptica em vidros fosfatos dopados com Sm3+ e Ho3+: transferência de energia e modelo LIR de múltiplos processos
Abstract: This study investigated the spectroscopic and thermo-optical properties of phosphate glas
ses belonging to the PAN10K system (40P2O5−15Al2O3−35Na2O−10K2O), doped with
Sm3+ ions and co-doped with Ho3+, with a focus on understanding energy transfer mecha
nisms and their application in optical thermometry. The samples were prepared via the
melt-quenching method and characterized using optical absorption spectroscopy, pho
toluminescence (including temperature-dependent lifetime measurements), and Raman
spectroscopy. Absorption spectra demonstrated the e cient incorporation of rare-earth
ions into the glass matrix, while Raman spectra allowed for correlating the phosphate
network structure with the observed optical processes. Analysis of Sm3+ emissions revea
led the inuence of dopant concentration on concentration quenching phenomena and on
the dynamics of radiative and non-radiative processes. In samples doped with Sm3+ and
co-doped with Ho3+, the Ho3+ ion was observed to modulate the Sm3+ electronic energy
level structure, thereby facilitating energy transfer mechanisms and altering the system’s
thermal response. The temperature dependence of luminescence intensity was descri
bed using a modi ed Arrhenius model involving multiple thermally activated processes,
enabling the determination of activation energies associated with non-radiative deactiva
tion and radiative activation mechanisms. Based on these results, a multi-process optical
thermometry model grounded in the luminescence intensity ratio (LIR) was developed;
this model is capable of accurately describing the thermal response of the samples under
various doping conditions. The sample containing 0.5% Sm3+ and 3% Ho3+ exhibited the
highest relative sensitivity, reaching 1.90% K−1 at 300 K. The results demonstrate that
the thermometric response of co-doped systems cannot be described exclusively by the
simpli ed model of coupled thermal populations, since energy transfer and non-radiative
relaxation processes can play a signi cant role in the population dynamics of the emitting
levels. Thus, this work contributes to a more comprehensive understanding of the physical mechanisms involved in luminescence-based optical thermometry.2026-07-27T00:00:00ZUma análise vertical da I maratona de Física da Universidade Federal de Uberlândia à luz da teoria antropológica do didáticohttps://repositorio.ufu.br/handle/123456789/501292026-09-05T06:21:03Z2026-03-06T00:00:00ZTitle: Uma análise vertical da I maratona de Física da Universidade Federal de Uberlândia à luz da teoria antropológica do didático2026-03-06T00:00:00ZAnálise térmica e óptica de íons de Nd e Yb em matriz PANK e seus efeitos para aplicações ópticas inovadorashttps://repositorio.ufu.br/handle/123456789/498292026-08-26T06:18:35Z2026-05-22T00:00:00ZTitle: Análise térmica e óptica de íons de Nd e Yb em matriz PANK e seus efeitos para aplicações ópticas inovadoras
Abstract: The present work employs thermoluminescent methodologies applied to a phosphate
glass (PANK) matrix doped with Nd³⁺ and Yb³⁺ rare-earth ions, aiming to determine the
thermo-optical properties of the system, whose concentrations, in weight percentage,
were systematically varied according to the xNd (4–x)Yb ratio, with x = 0, 1, 2, 3, and 4.
The experimental analyses consisted of investigating the excitation and de-excitation
processes of the 4f electrons of the dopant ions through measurements of the
luminescence peak, the emission ratio of each band, and the de-excitation lifetime. The
obtained results enabled the evaluation of luminescence dynamics, energy transfer
processes between the ions, the enhancement of emissive bands as a function of
temperature variation, and the identification of potential technological applications of the
material. Among the employed techniques, absorbance, photoluminescence (PL), and
average lifetime measurements are highlighted.2026-05-22T00:00:00Z