Abstract
Optical absorption spectra and luminescence spectra were recorded as a function of temperature between 295 K and 800 K for single crystal samples of Gd2SiO5:Dy3+, Lu2SiO5:Dy3+, LiNbO3:Dy3+, and Gd3Ga3Al2O12:Dy3+ fabricated by the Czochralski method and of YAl3(BO3)4:Dy3+ fabricated by the top-seeded high temperature solution method. A thermally induced change of fluorescence intensity ratio (FIR) between the 4I15/2→ 6H15/2 and 4F9/2 → 6H15/2 emission bands of Dy3+ was inferred from experimental data. It was found that relative thermal sensitivities SR at 350 K are higher for YAl3(BO3)4:Dy3+ and Lu2SiO5:Dy3+than those for the remaining systems studied. Based on detailed examination of the structural peculiarities of the crystals it was ascertained that the observed difference between thermosensitive features cannot be attributed directly to the dissimilarity of structural factors consisting of the geometry and symmetry of Dy3+ sites, the number of non-equivalent Dy3+ sites, and the host anisotropy. Instead, it was found that a meaningful correlation between relative thermal sensitivity SR and rates of radiative transitions of Dy3+ inferred from the Judd–Ofelt treatment exists. It was concluded that generalization based on the Judd–Ofelt parameters and luminescence branching ratio analysis may be useful during a preliminary assessment of thermosensitive properties of new phosphor materials.
Highlights
The remote temperature readout is a useful and meaningful method, and great attention has been addressed towards distinct advanced luminescence thermometers.For this purpose, various sophisticated luminescence systems and temperature sensor techniques have been proposed and elaborated on within the last decade
A temperature readout above a thousand degrees is possible for limited luminescence systems, but inorganic amorphous materials or lanthanide-doped crystals showing efficient emission within wide UV-Vis-NIR spectral regions can be satisfactorily utilized there, in contrast to fluorophores or bio-molecules, which are susceptible to destruction [6,7,8,9,10,11,12,13,14,15]
To be safe with interpreting the results, we focused our attention on the SR values at 350, and notice that these values for the YAl3 (BO3 )4 :4at.%Dy3+ (YAB):Dy and Lu2 SiO5 :5at.%Dy3+ (LSO):Dy systems are higher than those for the LiNbO3 :1.94at.%Dy3+ (LNO):Dy, GGAG:Dy, and Gd2 SiO5 :5at.%Dy3+ (GSO):Dy systems
Summary
The remote temperature readout is a useful and meaningful method, and great attention has been addressed towards distinct advanced luminescence thermometers. For this purpose, various sophisticated luminescence systems and temperature sensor techniques have been proposed and elaborated on within the last decade. In the present work we deal with the thermosensitive properties of Dy3+ -doped oxide crystals Their advantage over other rare-earth-doped phosphors stems from a specific energy level scheme of the Dy3+ ions, in which the energy separation between the 4 F9/2 luminescent level and the lower-energy dysprosium excited state is considerable, approaching 7000 cm−1.
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