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The thermal stability of oxyfluorotellurite glass systems, (65-x)TeO2 -20ZnF2 -12PbO-3Nb2O5 - xPr2O3 , doped with praseodymium was examined. The different concentrations of praseodymium oxide (x = 0.5 and 2 mol%) were applied to verify the thermal, optical and luminescence properties of the materials under study. The relatively high values of the Dietzel (∆T) and Saad–Poulain (S or H′ ) thermal stability factors determined using a differential thermal analysis (DTA) indicate the good thermal stability of the glass matrix, which gradually improves with the content of the active dopant. The temperature dependence of optical spectra in the temperature range 300–675 K for the VIS–NIR region was investigated. The involved Pr3+ optical transition intensities and relaxation dynamic of the praseodymium luminescent level were determined. The ultrashort femtosecond pulses were utilized to examine a dynamic relaxation of the praseodymium luminescent levels. Although the measured emission of the Pr3+ active ions in the studied glass encompasses the quite broad spectral region, the observed luminescence may only be attributed to 3PJ excited states. As a result, the observed decrease in the experimental lifetime for the 3P0 level along with the increasing activator content was identified as an intensification of the Pr–Pr interplay and the associated self-quenching process. The maximum relative sensitivities (Sr) estimated over a relatively wide temperature range are ~0.46% K−1 (at 300 K) for FIR (I530/I497) and 0.20% K−1 (at 600 K) for FIR (I630/I497), which seems to confirm the possibility of using investigated glasses in optical temperature sensors. [ABSTRACT FROM AUTHOR]

Crystals of Gd3Al2.5Ga2.5O12:Er3+, (Lu0.3Gd0.7)2SiO5:Er3+ and LiNbO3:Er3+ compounds differing in origin and the nature of their inherent structural disorder were crystalized. Optical absorption and luminescence spectra for transitions between the 4I15/2 and the 4I13/2 multiplets of Er3+ ions for the crystal samples were recorded versus temperatures in the region of 80–300 K. Gathered data were analyzed thoroughly providing the in-depth knowledge of the effects of temperature on intensities, wavelengths and bandwidths of Er3+ transitions. The information acquired together with the knowledge of significant structural dissimilarities of the host crystals chosen made it possible to propose an interpretation of the impact of a structural disorder in Er3+-doped crystals on their spectroscopic properties, and to determine their lasing ability at cryogenic temperatures upon resonant (in-band) optical pumping. [ABSTRACT FROM AUTHOR]

Novel ternary fluoro-germano-tellurite (GTS) glasses doped with Er3+ ions with 0.5 mol% and 1.0 mol% were fabricated by a conventional melt and quenching method and investigated using methods of optical spectroscopy. The room-temperature absorption spectrum was recorded and analyzed to determine radiative transition rates, radiative lifetimes, and branching ratios of Er3+ luminescence. Decay curves of Er3+ luminesccence were recorded and analyzed. Temperature dependences of emission spectra and absorption spectra in the region from RT (room-temperature) up to 675 K were studied in detail. The contribution of competing radiative and nonradiative processes to the relaxation of luminescent levels of Er3+ was assessed. Absolute and relative sensitivity were established utilizing the comprehensive model based on thermally coupled 2H11/2/4S3/2 excited states of erbium. The high quantum efficiency of the first erbium-excited state and value of gain coefficient indicate that GTS:Er glass system can be considered as conceivable NIR (near infrared) laser material as well. [ABSTRACT FROM AUTHOR]

The study recorded a low-temperature emission and polarized absorption spectra for U(super 3+) ions diluted in Cs3Lu2Cl9 and Cs3Y2I9 host crystals. The inadequacy in determination of the minor atomic parameters and the insufficient inclusion of the influence of excited configuration in the applied crystal field (CF) Hamiltonian are assumed to be main deficiencies preventing a better agreement between the experimental and calculated energies of CF levels.

Lead borate based glasses are analyzed using Raman and infrared spectroscopy along with the Er-doped lead borate glasses. In comparison to the precursor glasses, the luminescence intensities are higher, whereas the half-width of the luminescence lines slightly decreases in transparent oxyfluoride glass ceramics.

Highlights: [•] LGT:Er single crystals obtained by Czochralski method. [•] Analysis of absorption and emission spectra as well as decay curves of luminescence. [•] Influence of the temperature on the LGT:Er spectroscopic properties. [•] Spectroscopic evaluation of the LGT:Er potential laser qualities. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]