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Highlights: [•] Spectroscopic properties of rare earth doubly doped lead borate glasses were investigated. [•] Luminescence of Tb3+ was successfully detected under excitation of Dy3+. [•] Luminescence of Eu3+ was successfully detected under excitation of Tb3+. [•] The energy transfer processes between rare earth ions in lead borate glass were evidenced. [Copyright &y& Elsevier]

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]

Abstract: Lead borate glasses were prepared and then heat treated in order to obtain transparent glass-ceramics. Controlled crystallization of precursor lead borate glass at appropriate annealing temperature and time led to formation of the PbWO4 crystallites. The observed broad blue emission band is related to the PbWO4 crystallites. The influence of PbX2 content (X=F, Cl, Br), PbF2 concentration and lanthanide doping (Eu, Dy) on the excitation and emission spectra of lead borate glass-ceramics containing PbWO4 phase was examined. The relationship between Pb–X bond and spectral line width of the blue emission can be successfully observed, when halogen X ions (X=F, Cl or Br) are also present in the distorted PbWO4 crystallites. [Copyright &y& Elsevier]

Abstract: Structural and optical properties of Eu3+ and Dy3+ ions in PbO–Ga2O3–XO2 (X=Te, Ge, Si) glasses have been examined using X-ray diffraction, FT-IR and luminescence spectroscopy. Several crystalline phases such as TeO2, PbTe3O7, PbO and PbO2 were identified in lead tellurite system using X-ray diffraction analysis, in contrast to PbO–Ga2O3–XO2 (X=Ge, Si) glass samples. Characteristic emission bands due to the 5D0 → 7F J (J =0–4) transitions of Eu3+ and the 4F9/2 → 6H J /2 (J =15, 13, 11) transitions of Dy3+ were registered. Two spectroscopic parameters, such as luminescence intensity ratios associated to 5D0 → 7F2 and 5D0 → 7F1 transitions of Eu3+ as well as 4F9/2 → 6H13/2 and 4F9/2 → 6H15/2 transitions of Dy3+, and luminescence lifetimes for excited states of rare earth ions were determined. The luminescence intensity ratios for Eu3+ and Dy3+ ions decrease, whereas 5D0 (Eu3+) and 4F9/2 (Dy3+) luminescence lifetime increases, when covalence between Ln3+ and O2− ions is reduced and the phonon energy of the host glass is increased in PbO–TeO2 →PbO–GeO2 →PbO–SiO2 direction. It was confirmed by FT-IR measurements. [Copyright &y& Elsevier]

Heavy metal lead borate glasses doped with rare earth ions were examined. The influence of heavy metal oxide PbO and activator concentration on luminescence properties of rare earth ions are discussed. Rare earth ions were limited to Eu3+, Dy3+ and Tb3+ which are emitting in the visible light. Increasing concentration of lead oxide in relation to boron oxide causes an increase in R (Eu3+), Y/B (Dy3+) and G/B (Tb3+) spectroscopic factors which correspond to the relative integrated luminescence intensities of 5D0-7F2/5D0-7F1, 4F9/2-6H13/2/4F9/2-6H15/2 and 5D4-7F5/5D4-7F6 transitions, respectively. Moreover, the influence of heavy metal oxide and activator concentration on luminescence decays from excited states of rare earth ions was examined in details. [ABSTRACT FROM AUTHOR]

Abstract: Luminescence of lead bismuthate glasses PbO-Bi2O3-Ga2O3 containing Dy3+ ions has been studied. Two overlapping luminescence bands corresponding to 3P1–1S0 transition of Bi3+ and 4F9/2 –6H13/2 transition of Dy3+ were detected under 480nm excitation. Comparison of luminescence features for the system under study to those reported for dysprosium-doped lead borate glass PbO-B2O3-Ga2O3 indicates that the luminescence of Dy3+ is efficiently quenched by Bi3+ ions. Analysis of luminescence dynamics implies that the excitation energy transfer from Dy3+ to Bi3+ is nonradiative. The theoretical calculations using Inokuti–Hirayama model confirm strong luminescence of Dy3+ ions in lead bismuthate glasses. [Copyright &y& Elsevier]

Abstract: Dysprosium-doped heavy metal glasses and transparent glass–ceramics have been investigated using optical spectroscopy. Visible luminescence due to 4F9/2–6H J /2 (J =11, 13, 15) transitions of Dy3+ was registered. Based on excitation and emission spectra as well as luminescence decay analysis, some spectroscopic parameters for Dy3+ ions in glass samples before and after annealing were determined. Especially, the yellow-to-blue luminescence intensity ratios Y/B corresponding to the 4F9/2–6H15/2 and 4F9/2–6H13/2 transitions of Dy3+ ions were analyzed as a function of glass host composition and thermal treatment. [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]

The results presented in this communication concern visible and near-IR emission of Pr3+ ions in selected inorganic glasses, i.e., borate-based glass with Ga2O3 and BaO, lead-phosphate glass with Ga2O3, gallo-germanate glass modified by BaO/BaF2, and multicomponent fluoride glass based on InF3. Glasses present several emission bands at blue, reddish orange, and near-infrared spectral ranges, which correspond to 4f–4f electronic transitions of Pr3+. The profiles of emission bands and their relative intensity ratios depend strongly on glass-host. Visible emission of Pr3+ ions is tuned from red/orange for borate-based glass to nearly white light for multicomponent fluoride glass based on InF3. The positions and spectral linewidths for near-infrared luminescence bands at the optical telecommunication window corresponding to the 1G4 → 3H5, 1D2 → 1G4, and 3H4 → 3F3,3F4 transitions of Pr3+ are dependent on glass-host matrices and excitation wavelengths. Low-phonon fluoride glasses based on InF3 and gallo-germanate glasses with BaO/BaF2 are excellent candidates for broadband near-infrared optical amplifiers. Spectroscopic properties of Pr3+-doped glasses are compared and discussed in relation to potential optical applications. [ABSTRACT FROM AUTHOR]

This study presented an analysis of the TeO2/GeO2 molar ratio in an oxide glass system. A family of melt-quenched glasses with the range of 0–35 mol% of GeO2 has been characterized by using DSC, Raman, MIR, refractive index, PLE, PL spectra, and time-resolved spectral measurements. The increase in the content of germanium oxide caused an increase in the transition temperature but a decrease in the refractive index. The photoluminescence spectra of europium ions were examined under the excitation of 465 nm, corresponding to 7F0 → 5D2 transition. The PSB (phonon sidebands) analysis was carried out to determine the phonon energy of the glass hosts. It was reported that the red (5D0 → 7F2) to orange (5D0 → 7F1) fluorescence intensity ratio for Eu3+ ions decreased from 4.49 (Te0Ge) to 3.33 (Te15Ge) and showed a constant increase from 4.58 (Te20Ge) to 4.88 (Te35Ge). These optical features were explained in structural studies, especially changes in the coordination of [4]Ge to [6]Ge. The most extended lifetime was reported for the Eu3+ doped glass with the highest content of GeO2. This glass was successfully used for the drawing of optical fiber. [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]

Abstract: Results of X-ray diffraction, infrared spectroscopy, differential scanning calorimetry and optical emission together with lifetime measurements of phosphate fluoroindate glasses activated by Pr3+ ions are reported. Structural, thermal and optical behavior of multicomponent oxyfluoride glasses has been analyzed as a function of P2O5 concentration. Short glass-forming region exists for InF3-based system with P2O5 additives. For low (4–12%) P2O5 concentration, thermally stable and transparent non-crystalline oxyfluoride samples based on InF3 with relatively high ΔT factors were prepared, which can be promising for fiber drawing. For higher (16%) P2O5 concentrations, several diffraction lines due to the InOF polycrystalline phase were identified. Absorption edge and luminescence bands for Pr3+ ions in fluoroindate glasses are shifted in the direction of the lower frequency region with increasing of P2O5 content. Luminescence from both 3P0 and 1D2 excited states of Pr3+ ions was registered. The 1D2 luminescence lifetime close to about 35μs is independent on P2O5 concentration. [Copyright &y& Elsevier]

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: Influence of rare earth ions on structural behavior in lead borate glasses has been investigated using infrared spectroscopy. The structural changes have been analyzed with increasing rare earth concentration. Partial BO3↔BO4 conversion as a function of rare earth concentration is observed only for the smaller heavier lanthanides, whereas for the larger lighter lanthanides the concentration effect has not been found. [Copyright &y& Elsevier]

Glasses containing two different network-forming components and doped with optically active ions exhibit interesting properties. In this work, glass systems based on germanium dioxide and boron trioxide singly doped with lanthanides (Eu3+) and transition metals (Cr3+) ions are research subjects. Optical spectroscopy was the major research tool used to record excitation and emission spectra in a wide spectral range for studied systems. The emitted radiation of glasses doped with Cr3+ ions is dominated by broadband luminescence centered at 770 nm and 1050 nm (4T2 → 4A2). Interestingly, the increase of concentration of one of the oxides contributed to the detectable changes of the R-line (2E → 4A2) of Cr3+ ions. Moreover, EPR spectroscopy confirmed the paramagnetic properties of the obtained glasses. The influence of molar ratio GeO2:B2O3 on spectroscopic properties for Eu3+ ions is discussed. The intensity of luminescence bands due to transitions of trivalent europium ions as well as the ratio R/O decrease with the increase of B2O3. On the other hand, the increase in concentration B2O3 influences the increasing tendency of luminescence lifetimes for the 5D0 state of Eu3+ ions. The results will contribute to a better understanding of the role of the glass host and thus the prospects for new optical materials. [ABSTRACT FROM AUTHOR]

Modified barium gallo-germanate glass hosts are still worthy of attention in studying structure–property relationships. In this work, two different series of glass systems based on (60-x)GeO2-xTiO2-30BaO-10Ga2O3 and (60-x)GeO2-xB2O3-30BaO-10Ga2O3 (x = 10, 30, 50 mol%) were synthesized, and their properties were studied using spectroscopic techniques. X-ray diffraction (XRD) patterns revealed that all fabricated glasses were fully amorphous material. The absorption edge shifted toward the longer wavelengths with a gradual substitution of GeO2. The spectroscopic assignments of titanium ions were performed with excitation and emission spectra compared to the additional sample containing an extremely low content of TiO2 (0.005 mol%). On the basis of Raman and FT-IR investigations, it was found that increasing the TiO2 content caused a destructive effect on the GeO4 and GeO6 structural units. The Raman spectra of a sample containing a predominantly TiO2 (50 mol%) proved that the band was located near 650 cm−1, which corresponded to the stretching vibration of Ti-O in TiO6 unit. The deconvoluted IR results showed that the germanate glass network consisted of the coexistence of two BO3 and BO4 structural groups. Based on the experimental investigations, we concluded that the developed materials are a promising candidate for use as novel glass host matrices for doping rare-earth and/or transition metal ions. [ABSTRACT FROM AUTHOR]

In this paper, the effect of the GeO2:TiO2 molar ratio in glass composition on the spectroscopic properties of germanate glasses was systematically investigated. The visible luminescence bands associated with characteristic 1D2 → 3H4 (red), 5S2, 5F4 → 5I8 (green), and 1D2 → 3F4 (blue) transitions of Pr3+, Ho3+, and Tm3+ ions in systems modified by TiO2 were well observed, respectively. It was found that the luminescence intensity of glasses containing Pr3+ and Ho3+ ions increases, whereas, for Tm3+-doped systems, luminescence quenching with increasing content of TiO2 was observed. Based on Commission Internationale de I'Eclairage (CIE) chromaticity coordinates (x, y) analysis, it was demonstrated that the value of chromaticity coordinates for all glasses depends on the GeO2:TiO2 molar ratio. The addition of TiO2 to system compositions doped with Tm3+ ions shifts the (x, y) to the center of the CIE diagram. However, chromaticity coordinates evaluated for glasses containing Pr3+ ions move to a purer red color. Our results confirm that the spectroscopic properties of the studied glasses strongly depend on TiO2 content. Moreover, it can be stated that germanate-based glass systems modified by TiO2 can be used for optoelectronics in RGB technology as red (Pr3+), green (Ho3+), and blue (Tm3+) emitters. [ABSTRACT FROM AUTHOR]

Influence of titanium dioxide concentration on thermal properties of germanate-based glasses has been studied. Germanate glasses varying with TiO2 content were examined using DSC methods. The DSC curves exhibit two exothermic peaks, when GeO2 is substituted by TiO2. Based on DSC measurements, characteristic temperatures were determined. The studies demonstrate that glass transition temperature increases, whereas thermal stability parameters are reduced with increasing TiO2 concentration. The DSC curves were also acquired with different heating rates, and the Kissinger method was used to calculate the activation energy. X-ray diffraction analysis for germanate-based glass with TiO2 indicates that crystallization processes are more complex and several phases are formed during annealing. The absorption and emission spectra of glass samples doped with Er3+ ions were also examined before and after annealing process. [ABSTRACT FROM AUTHOR]

An investigation of the structural and luminescent properties of the transparent germanate glass-ceramics co-doped with Ni2+/Er3+ for near-infrared optical fiber applications was presented. Modification of germanate glasses with 10–20 ZnO (mol.%) was focused to propose the additional heat treatment process controlled at 650 °C to obtain transparent glass-ceramics. The formation of 11 nm ZnGa2O4 nanocrystals was confirmed by the X-ray diffraction (XRD) method. It followed the glass network changes analyzed in detail (MIR—Mid Infrared spectroscopy) with an increasing heating time of precursor glass. The broadband 1000–1650 nm luminescence (λexc = 808 nm) was obtained as a result of Ni2+: 3T2(3F) → 3A2(3F) octahedral Ni2+ ions and Er3+: 4I13/2 → 4I15/2 radiative transitions and energy transfer from Ni2+ to Er3+ with the efficiency of 19%. Elaborated glass–nanocrystalline material is a very promising candidate for use as a core of broadband luminescence optical fibers. [ABSTRACT FROM AUTHOR]

This paper deals with broadband near-infrared luminescence properties of lead germanate glass triply doped with Yb3+/Er3+/Tm3+. Samples were excited at 800 nm and 975 nm. Their emission intensities and lifetimes depend significantly on Er3+ and Tm3+ concentrations. For samples excited at 800 nm, broadband emissions corresponding to the overlapped 3H4 → 3F4 (Tm3+) and 4I13/2 → 4I15/2 (Er3+) transitions centered at 1.45 µm and 1.5 µm was identified. Measurements of decay curves confirm reduction of 3H4 (Tm3+), 2F5/2 (Yb3+) and 4I13/2 (Er3+) luminescence lifetimes and the presence of energy-transfer processes. The maximal spectral bandwidth equal to 269 nm for the 3F4 → 3H6 transition of Tm3+ suggests that our glass co-doped with Yb3+/Er3+/Tm3+ is a good candidate for broadband near-infrared emission. The energy transfer from 4I13/2 (Er3+) to 3F4 (Tm3+) and cross-relaxation processes are responsible for the enhancement of broadband luminescence near 1.8 µm attributed to the 3F4 → 3H6 transition of thulium ions in lead germanate glass under excitation of Yb3+ ions at 975 nm. [ABSTRACT FROM AUTHOR]

This work reports on the fabrication and analysis of near-infrared and mid-infrared luminescence spectra and their decays in fluoroindate glasses co-doped with Yb3+/Ho3+. The attention has been paid to the analysis of the Yb3+→ Ho3+ energy transfer processed ions in fluoroindate glasses pumped by 976 nm laser diode. The most effective sensitization for 2 μm luminescence has been obtained in glass co-doped with 0.8YbF3/1.6HoF3. Further study in the mid-infrared spectral range (2.85 μm) showed that the maximum emission intensity has been obtained in fluoroindate glass co-doped with 0.1YbF3/1.4HoF3. The obtained efficiency of Yb3+→ Ho3+ energy transfer was calculated to be up to 61% (0.8YbF3/1.6HoF3), which confirms the possibility of obtaining an efficient glass or glass fiber infrared source for a MID-infrared (MID-IR) sensing application. [ABSTRACT FROM AUTHOR]

In this work, the series of Tb3+/Eu3+ co-doped xerogels and derivative glass-ceramics containing CaF2 nanocrystals were prepared and characterized. The in situ formation of fluoride crystals was verified by an X-ray diffraction technique (XRD) and transmission electron microscopy (TEM). The studies of the Tb3+/Eu3+ energy transfer (ET) process were performed based on excitation and emission spectra along with luminescence decay analysis. According to emission spectra recorded under near-ultraviolet (NUV) excitation (351 nm, 7F6 → 5L9 transition of Tb3+), the mutual coexistence of the 5D4 → 7FJ (J = 6–3) (Tb3+) and the 5D0 → 7FJ (J = 0–4) (Eu3+) luminescence bands was clearly observed. The co-doping also resulted in gradual shortening of a lifetime from the 5D4 state of Tb3+ ions, and the ET efficiencies were varied from ηET = 11.9% (Tb3+:Eu3+ = 1:0.5) to ηET = 22.9% (Tb3+:Eu3+ = 1:2) for xerogels, and from ηET = 25.7% (Tb3+:Eu3+ = 1:0.5) up to ηET = 67.4% (Tb3+:Eu3+ = 1:2) for glass-ceramics. Performed decay analysis from the 5D0 (Eu3+) and the 5D4 (Tb3+) state revealed a correlation with the change in Tb3+–Eu3+ and Eu3+–Eu3+ interionic distances resulting from both the variable Tb3+:Eu3+ molar ratio and their partial segregation in CaF2 nanophase. [ABSTRACT FROM AUTHOR]

In this work, spectroscopic properties of europium and erbium ions in heavy metal oxide glasses have been studied. The phonon energy of the glass host was determined based on Eu3+ excitation spectra measurements. Near-IR emission spectra at 1550 nm related to 4I13/2 → 4I15/2 transition of erbium in heavy metal glasses were examined with special regards to luminescence bandwidth and measured lifetime. In particular, correlation between phonon energy and the measured lifetime 4I13/2 (Er3+) was proposed. The luminescence lifetime for the 4I13/2 upper laser state of erbium decreases with increasing phonon energy in glass matrices. Completely different results were obtained glass samples with europium ions, where the 5D0 lifetime increases with increasing phonon energy. Our investigations suggest that the values of measured 5D0 lifetime equal to radiative lifetimes for all heavy metal oxide glasses. [ABSTRACT FROM AUTHOR]

Lead tungstate PbWO4 nanocrystals in transparent lead borate glass-ceramics containing Er3+ ions were fabricated. Luminescence spectra at about 1530 nm due to main 4 I13/2-4 I15/2 laser transition of Er3+ ions were examined for glass samples before and after heat treatment. Near-infrared luminescence of Er3+ ions in glass-ceramics is enhanced and long-lived in comparison to precursor glasses. It suggests that the Er3+ ions are partially incorporated into PbWO4 crystalline phase. [ABSTRACT FROM AUTHOR]

Abstract: Visible luminescence of Dy3+ ions in oxyhalide lead borate glasses was examined. Luminescence spectra show two intense bands at 480nm and 573nm due to 4F9/2 → 6H15/2 (blue) and 4F9/2 → 6H13/2 (yellow) transitions of Dy3+. Luminescence decays from 4F9/2 state and yellow-to-blue luminescence intensity ratios (Y/B) were analysed with PbX2 (X=F, Cl) content. An introduction of PbX2 to the borate glass results in the increasing of 4F9/2 lifetime and the decreasing of yellow-to-blue luminescence intensity ratio, which is due to reduction of covalency between Dy3+ and O2−/X− ions. [Copyright &y& Elsevier]

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]