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.