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Abstract: Effects of PbF2 concentration on spectroscopic properties of Eu3+ and Dy3+ ions in lead borate glasses have been studied. The samples where PbO was partially or totally substituted by PbF2 were examined using DSC, FT-IR, Raman, absorption and luminescence spectroscopies. Luminescence spectra and their decays were analyzed in detail. Especially, the luminescence intensity ratios R (Eu3+) and Y/B (Dy3+) as well as luminescence lifetimes of 5D0 (Eu3+) and 4F9/2 (Dy3+) excited states of rare earth ions have been determined. [Copyright &y& Elsevier]

Abstract Oxyfluoride lead-based and lead-free germanate glasses were heat-treated in order to fabricate transparent glass-ceramics. Cubic β-PbF 2 nanocrystals are well formed during crystallization of lead germanate glass. The up-conversion luminescence spectra of Er3+ ions in lead germanate glass-ceramic system are enhanced significantly due to partial incorporation of the optically active ions into fluoride crystalline phase. These effects are not significant in oxyfluoride lead-free germanate glass after heat treatment process. The crystallization of barium gallo-germanate glass with BaF 2 is more complex and the presence of four crystalline phases BaF 2 , BaO, Ba 3 Ga 2 Ge 4 O 14 and GeO 2 was verified by X-ray diffraction measurements. Highlights • Er3+-doped germanate glasses before and after heat treatment have been examined. • PbF 2 nanocrystals are formed during heat treatment of lead germanate glass. • Four crystalline phases were identified in lead-free germanate glass-ceramic. • Up-conversion emission spectra of Er3+ in glass and glass-ceramic were compared. [ABSTRACT FROM AUTHOR]

In this work, the electrical and optical properties of glasses and glass-ceramics are presented and discussed in details. Several electrical and optical parameters for glasses and glass-ceramics were determined. The conduction activation energy and DC conductivity depend on temperature, glass composition and concentration of glass modifiers. The optical properties of glasses and glass-ceramics containing Er 3+ (or Er 3+ /Yb 3+ ) ions have been analyzed for near-infrared luminescence centered at about 1.5 μm and up-conversion applications. In particular, luminescence bandwidths and lifetimes for the 4 I 13/2  →  4 I 15/2 transition of Er 3+ were determined as a function of host-matrices and then examined for near-infrared solid-state lasers and broadband optical amplifiers. The green up-conversion luminescence spectra for Er 3+ and Er 3+ /Yb 3+ doped systems are temperature-dependent and can be used to optical sensors. [ABSTRACT FROM AUTHOR]

Rare earth doped lead-free oxide and oxyfluoride germanate glasses were synthesized. The rare earths as an optically active ions were limited to trivalent Eu 3 + . One of the glass modifier components is MO (M = Ca, Sr or Ba), which was partially or totally substituted by MF 2 in chemical composition. The influence of glass modifiers on structure of lead-free-germanate glasses was examined using X-ray diffraction analysis. In contrast to samples containing modifier MO (M = Ca or Sr), samples with BaO and/or BaF 2 are fully amorphous. For the amorphous samples, the emission properties of Eu 3 + ions were studied. The emission spectra of Eu 3 + ions and their decays in glass samples with different BaF 2 contents were analyzed. Several spectroscopic parameters, such as fluorescence intensity ratio R/O (Eu 3 + ) and measured luminescence lifetime for 5 D 0 state of Eu 3 + are presented and discussed in details. [ABSTRACT FROM AUTHOR]

Abstract: Luminescence properties of Tb3+–Eu3+ doubly doped lead borate glasses were investigated. Luminescence spectra were measured under different excitation wavelengths. Characteristic luminescence bands related to electronic transitions of trivalent terbium and europium ions were detected under direct excitation of Tb3+. The energy transfer from Tb3+ to Eu3+ in lead borate glass occurs through a nonradiative process with an efficiency up to 18%. The presence of energy transfer process was also confirmed by excitation spectra measurements. [Copyright &y& Elsevier]