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Lead borate glasses doubly doped with Dy(3)(+)-Tb(3+) and Tb(3+)-Eu(3+) were investigated using optical spectroscopy. Luminescence spectra of rare earths were detected under various excitation wavelengths. The main green emission band due to (5)D4→(7)F5 transition of Tb(3+) is observed under excitation of Dy(3+), whereas the main red emission band related to (5)D0→(7)F2 transition of Eu(3+) is successfully observed under direct excitation of Tb(3+). In both cases, the energy transfer processes from Dy(3+) to Tb(3+) and from Tb(3+) to Eu(3+) in lead borate glasses occur through a nonradiative processes with efficiencies up to 16% and 18%, respectively. The presence of energy transfer process was also confirmed by excitation spectra measurements., (Copyright © 2014 Elsevier B.V. All rights reserved.)

Visible luminescence of Dy(3+) ions in oxyhalide lead borate glasses was examined. Luminescence spectra show two intense bands at 480 nm and 573 nm due to (4)F(9/2)→(6)H(15/2) (blue) and (4)F(9/2)→(6)H(13/2) (yellow) transitions of Dy(3+). Luminescence decays from (4)F(9/2) state and yellow-to-blue luminescence intensity ratios (Y/B) were analysed with PbX(2) (X=F, Cl) content. An introduction of PbX(2) to the borate glass results in the increasing of (4)F(9/2) lifetime and the decreasing of yellow-to-blue luminescence intensity ratio, which is due to reduction of covalency between Dy(3+) and O(2-)/X(-) ions., (Copyright © 2010 Elsevier B.V. All rights reserved.)

Lead-free oxyfluoride borate glasses singly doped with Pr 3+ and Er 3+ were prepared and next investigated using absorption and luminescence spectroscopy. In the studied glass system, barium oxide was substituted by BaF 2 . Two luminescence bands of Pr 3+ located at visible spectral region are observed, which correspond to 3 P 0 – 3 H 4 (blue) and 1 D 2 – 3 H 4 (reddish orange) transitions, respectively. The luminescence bands due to 1 D 2 – 3 H 4 transition of Pr 3+ are shifted to shorter wavelengths, when BaO was substituted by BaF 2 . Near-infrared luminescence spectra of Er 3+ ions in lead-free borate glasses modified by BaF 2 correspond to 4 I 13/2 – 4 I 15/2 transition. Their spectral linewidths increase with increasing BaF 2 concentration. The changes in measured lifetimes of rare earth ions are well correlated with the bonding parameters calculated from the optical absorption spectra. [ABSTRACT FROM AUTHOR]

Abstract: Ln-doped oxychloride lead borate glasses were studied using luminescence spectroscopy. Rare earth ions were limited to trivalent Pr3+, Tm3+, Eu3+ and Er3+. Luminescence spectra were registered, which correspond to 3P0–3H4 and 1D2–3H4 transitions of Pr3+, 1G4–3H5 and 1G4–3F4 transitions of Tm3+, 5D0–7F J (J=0, 1, 2, 3, 4) transitions of Eu3+ and 4S3/2,2H11/2–4I15/2 and 4I13/2–4I15/2 transitions of Er3+. Luminescence decays from the excited states of Ln3+ ions were analyzed in detail. The experimental results indicate that relatively high phonon energy of the host gives important contribution to the excited state relaxation of rare earth ions. [Copyright &y& Elsevier]

Abstract: The spectroscopic and laser properties of Nd3+ and Dy3+ ions in lead borate glass were studied. Luminescence spectra recorded in the near-infrared and visible ranges correspond to 4F3/2–4I J /2 (J=9, 11, 13) transitions of Nd3+ and 4F9/2–6H J /2 (J=11, 13, 15) transitions of Dy3+, respectively. Luminescence decay curves were analyzed as a function of activator concentration. Luminescence quenching is observed, which is due to Ln–Ln interaction increasing. Several spectroscopic parameters relevant to laser potential of Ln3+ ions (Ln=Nd, Dy) in lead borate glass were determined. The relatively large values of the quantum efficiency and the room-temperature emission cross-section for the 4F3/2–4I11/2 transition of Nd3+ at 1061nm and the 4F9/2–6H13/2 transition of Dy3+ at 573nm imply that Ln-doped lead borate glasses can be considered as promising solid-state materials for laser applications. [Copyright &y& Elsevier]

Oxychloroborate glasses containing Dy3+ ions in the B2O3-PbCl2-PbO-Al2O3-WO3 system were studied using X-ray diffraction, Raman, FT-IR, absorption, excitation and luminescence spectroscopy. The results concerning glass preparation, short-range order structure and optical properties are reported. X-ray diffraction analysis evidently indicates that the fully amorphous system was prepared. Coexistence of trigonal BO3 and tetrahedral BO4 units was evidenced by Raman and FT-IR spectroscopy. The electronic states belonging to the 4f 9 configuration of trivalent Dy3+ were determined from the absorption and excitation spectra. The luminescence bands at 480, 573 and 662 nm were registered in oxychloride glasses, which correspond to transitions originating from the 4F9/2 state to the 6HJ/2 (J = 11, 13, 15) states of Dy3+. [ABSTRACT FROM AUTHOR]

Oxyhalide lead borate glasses doped with rare earth ions have been studied before and after thermal treatment. The rare earths as optically active ions were limited to the Er3+ ions. Near-infrared luminescence due to the main 4I13/2-4I15/2 laser transition of Er3+ was registered. The introduction of PbX2 to the borate glass results in a reduction of spectral linewidth and an increase of luminescence lifetime of 4I13/2 state of Er3+ ions. The unusual large spectral linewidth for 4I13/2-4I15/2 transition of Er3+ in the oxide glass host was obtained, whereas the luminescence decay from 4I13/2 state is longer for a sample with PbF2 than PbCl2 and PbBr2. Heat treatment introduces transformation from a glass to transparent glass-ceramic (TGC). The coordination sphere around Er3+ ions is changed, giving important contribution to the luminescence characteristics. The spectroscopic consequence of this transformation is the increase of luminescence lifetime and the narrowing of spectral lines of Er3+. [ABSTRACT FROM AUTHOR]

Oxyfluoride lead borate glasses singly doped with Nd3+ and Er3+ ions have been studied before and after thermal treatment. The orthorhombic PbF2 crystallites are formed during thermal treatment, which was evidenced by X-ray diffraction analysis. Near-infrared luminescence spectra at 1.06 µm and 1.53 µm have been registered for samples before and after annealing, which correspond to the main 4F3/2-4I11/2 and 4I13/2-4I15/2 laser transitions of Nd3+ and Er3+ ions, respectively. Luminescence decays from 4F3/2 state of Nd3+ and 4I13/2 state of Er3+ have been analyzed in detail. Contrary to Nd-doped samples, the luminescence lines obtained for Er-doped transparent oxyfluoride glass-ceramics are more intense and narrowed, whereas the luminescence decays from 4I13/2 state of Er3+ are slightly longer in comparison to precursor glasses. [ABSTRACT FROM AUTHOR]

Energy transfer processes from Cr3+ to Nd3+ and NIR luminescence of Nd3+ ions at 1.06 µm in Cr-Nd co-doped lead borate glasses have been investigated. The spectroscopic investigation indicates that Cr3+ ions are located at strong-field and weak-field sites. Replacing PbO by PbF2 in lead borate glasses slightly influences the energy transfer processes between Cr3+ and Nd3+ and NIR luminescence of Nd3+ ions. The energy transfer process occurs in both oxide and oxyfluoride glass systems, which may be due to the thermally induced population of the 4T2 excited state of Cr3+ ions and the participation of lattice phonons. [ABSTRACT FROM AUTHOR]

Energy transfer processes in lead borate glasses doubly doped with Yb-Tm and Yb-Er have been investigated at room temperature under excitation of Yb at 975 nm. The non-resonant energy transfer from ²F5/2 state of Yb to ³H5 state of Tm results in up-converted emission at 850 nm due to the ³H4-³H6 transition of thulium ions. The nearly resonant transfer from ²F5/2 state of Yb to 4I11/2 state of Er results in green up-conversion and near-infrared emission, which correspond to the 4S3/2-4I15/2 and 4I13/2-4I15/2 transitions of erbium ions, respectively. High Yb concentration in both co-doped samples is required for optimal energy transfer efficiency (η > 90%). Results with the singly Yb-doped samples are also presented to clarify the energy transfer process. [ABSTRACT FROM AUTHOR]

Abstract: Dy-doped lead borate glasses were studied. The luminescence spectra showed two characteristic bands at 480 and 573nm due to 4F9/2–6H15/2 (blue) and 4F9/2–6H13/2 (yellow) transitions of Dy3+. The yellow/blue luminescence of trivalent dysprosium was analyzed as a function of the B2O3/PbO ratios, the activator (Dy3+) and the PbX2 (X=F, Cl, Br) content. [Copyright &y& Elsevier]

Abstract: Transparent glass-ceramics were successfully prepared during controlled heat treatment of lead borate glasses. The PbF2 particles were dispersed into a borate glass matrix which was evidenced by X-ray diffraction analysis. The phase identification revealed that crystalline peaks can be related to the orthorhombic PbF2 phase. Green up-conversion luminescence due to the 4S3/2–4I15/2 transition of Er3+ ions was registered. In comparison to the precursor glass the luminescence intensity was considerably higher, whereas the luminescence linewidth slightly decreased in the studied oxyfluoride transparent glass-ceramics. It indicated that apart of the trivalent erbium was incorporated into the PbF2 crystalline phase. [Copyright &y& Elsevier]

Abstract: Near-infrared luminescence spectra at 1.53μm due to main 4I13/2–4I15/2 laser transition of Er3+ ions in oxide and oxyhalide lead borate glasses were examined. Spectroscopic parameters like spectral linewidth and luminescence lifetime were analyzed with PbX2 (X=F, Cl or Br) doping. An introduction of lead halide to the borate glass results in the reduction of spectral linewidth and the increase of luminescence lifetime of Er3+. The luminescence decay from the 4I13/2 upper state of Er3+ is longer for glass sample with PbF2 than PbX2 (X=Cl or Br). [Copyright &y& Elsevier]

Lead borate glasses singly and doubly doped with Tm 3+ and Dy 3+ were prepared by traditional melt-quenching technique. The emission spectra of rare earths in studied glass systems were registered under different excitation wavelengths. The observed emission bands are located in the visible spectral region. They correspond to 1 D 2 → 3 F 4 (blue) and 1 G 4 → 3 H 6 (blue) transitions of Tm 3+ as well as 4 F 9/2 → 6 H 15/2 (blue), 4 F 9/2 → 6 H 13/2 (yellow) and 4 F 9/2 → 6 H 11/2 (red) transitions of Dy 3+ . Moreover, the energy transfer process from Tm 3+ to Dy 3+ was observed. The luminescence bands originating to characteristic transitions of thulium and dysprosium ions are present on emission spectra under direct excitation of Tm 3+ . Luminescence lifetimes for the excited states of Tm 3+ and Dy 3+ ions in lead borate glass were also determined based on decay measurements. The luminescence intensities and lifetimes depend significantly on the relative concentrations of the optically active dopants. [ABSTRACT FROM AUTHOR]