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• Optical properties of titanate-germanate glasses doped with Ho3+ ions were studied. • Near-IR emission spectra of Ho3+and their decays were examined with TiO 2 content. • Spectroscopic parameters for Ho3+ ions in titanate-germanate glass were determined. • Higher concentrations of TiO 2 are preferred for near-IR luminescence at 2 µm. Holmium-doped titanate-germanate glasses have been investigated for optical applications. Near-infrared luminescence at 2 μm due to 5I 7 → 5I 8 transition of holmium ions has been examined in function of TiO 2 concentration. Several spectroscopic parameters for holmium ions such as emission linewidth and lifetime, stimulated emission cross-section and quantum efficiency were determined based on absorption and luminescence experiments and calculated using the Judd-Ofelt theory. Systematic studies demonstrate that holmium-doped titanate-germanate glasses with higher TiO 2 concentration show excellent optical properties. Multicomponent glasses with molar ratios GeO 2 :TiO 2 = 1:2 and 1:3 are recommended for near-infrared luminescence at 2 μm. [Display omitted] [ABSTRACT FROM AUTHOR]

The influence of Cr3+ concentration on near-infrared emission of Ho3+ in barium gallo-germanate glass has been studied. Near-infrared emission bands, due to 4T 2 → 4A 2 (Cr3+) as well as 5I 6 → 5I 8 and 5I 7 → 5I 8 (Ho3+) transitions, were observed under excitation of Cr3+. The enhanced and broadband near-infrared emission was obtained for glasses in the presence of transition metal (Cr3+) and rare earth (Ho3+) ions. This prosperity was optimized as a function of donor (Cr3+) and acceptor (Ho3+) concentration. The integrated intensities of emission bands were determined and their values are found to be maximal at 0.25 mol% Cr3+ and 0.5 mol% Ho3+. The energy transfer from Cr3+ to Ho3+ occurs through a nonradiative process with an efficiency up to 23%. • Cr3+/Ho3+ co-doped barium gallo-germanate glasses were studied for NIR emission. • NIR emission spectra of Ho3+ ions in glasses were measured under excitation of Cr3+. • Emission bands are due to 4T 2.→ 4A 2 (Cr3+), 5I 6 → 5I 8 and 5I 7 → 5I 8 (Ho3+) transitions • The relative emission band intensities of Ho3+ depend critically on Cr3+ concentration. • The energy transfer from Cr3+ to Ho3+ with an efficiency up to 23% occurs. [ABSTRACT FROM AUTHOR]

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]

Near-infrared luminescence properties of Nd 3+ and Ho 3+ ions in barium gallo-germanate glasses have been reported. Several spectroscopic parameters for Nd 3+ and Ho 3+ ions have been determined from the Judd-Ofelt analysis and absorption/luminescence measurements. Quite large luminescence lifetime, quantum efficiency and stimulated emission cross-section have been obtained for the main 4 F 3/2  →  4 I 11/2 (Nd 3+ ) and 5 I 7  →  5 I 8 (Ho 3+ ) laser transitions of rare earths in barium gallo-germanate glasses. It suggests that barium gallo-germanate glass is promising for near-infrared laser application at emission wavelengths 1064 nm (Nd 3+ ) and 2020 nm (Ho 3+ ). [ABSTRACT FROM AUTHOR]

In this work, Tm3+ doped and Tm3+/Ho3+ co-doped germanate glasses with various TiO 2 concentrations have been examined using optical spectroscopy. The broad emission bands corresponding to 3F 4 →3H 6 (1.8 μm) and 5I 7 →5I 8 (2 μm) transitions of thulium and holmium ions were registered, respectively. It was observed that the intensity of near-infrared emission bands significantly changes with increasing titanium oxide content in the glass composition. Furthermore, the energy transfer process from Tm3+ to Ho3+ ions in studied glass systems was confirmed and discussed. The dependence of spectroscopic parameters like full width at half maximum (FWHM) and energy transfer efficiency (η ET) on increased TiO 2 concentration in glass host was established. [ABSTRACT FROM AUTHOR]

Near‐infrared (NIR) luminescence of Pr3+ and Tm3+ ions in titanate‐germanate glasses has been studied for laser and fiber amplifier applications. The effect of the molar ratio GeO2:TiO2 (from 5:1 to 1:5) on spectroscopic properties of glass systems was studied by absorption, luminescence measurements, and theoretical calculations using the Judd–Ofelt theory. It was found that independent of the TiO2 concentration, intense NIR emissions at 1.5 and 1.8 μm were observed for glasses doped with Pr3+ and Tm3+ ions, respectively. Moreover, several spectroscopic and NIR laser parameters for Pr3+ and Tm3+ ions, such as emission bandwidth, stimulated emission cross‐section, quantum efficiency, gain bandwidth, and figure of merit, were determined. The results were discussed in detail and compared to the different laser glasses. Systematic investigations indicate that Pr3+‐doped system with GeO2:TiO2 = 2:1 and Tm3+‐doped glass with GeO2:TiO2 = 1:2 present profit laser parameters and could be successfully applied to NIR lasers and broadband optical amplifiers. [ABSTRACT FROM AUTHOR]

Lead phosphate based glasses doubly doped with Tb 3+ and Eu 3+ ions were prepared and next studied using different spectroscopic techniques. Structural and optical properties of Tb 3+ and Eu 3+ ions have been investigated in lead phosphate based systems, in which PbO:P 2 O 5 molar ratio were changed from 1:5 to 5:1 in glass composition. The fourier transform infrared (FT-IR) spectroscopy was used to verify local structure of glass-network. The FT-IR spectra clearly indicate that different structural phosphate groups are present in PbO-P 2 O 5 based glasses. Moreover, the areas of the FT-IR bands strongly depend on the relative ratio of PbO and P 2 O 5 components. The luminescence spectra for Eu 3+ and Tb 3+ ions in PbO-P 2 O 5 glasses were registered. Several emission bands associated to characteristic transitions of trivalent europium and terbium are observed under direct excitation of Tb 3+ ions. It indicates that the energy transfer process from Tb 3+ to Eu 3+ in lead phosphate glasses occurs. Spectroscopic parameters like 5 D 0 (Eu 3+ ) and 5 D 4 (Tb 3+ ) luminescence lifetimes were determined. Dependence of spectroscopic parameters on the increase of PbO:P 2 O 5 molar ratio from 1:5 to 5:1 in glass composition was established. [ABSTRACT FROM AUTHOR]

In this work, luminescence properties of Tb 3+ /Sm 3+ co-doped lead borate glasses are examined in details. Luminescence spectra of rare earths were measured under different excitation wavelengths. Characteristic luminescence bands corresponding to electronic transitions of terbium and samarium ions were detected under direct excitation of Tb 3+ . The energy transfer from Tb 3+ to Sm 3+ ions in lead borate glass occurs through a nonradiative process with an efficiency from 0.6% to 16%, depending on samarium concentration. Luminescence decay curves for the 4 G 5/2 state of Sm 3+ ions in lead borate glasses were fitted using the Inokuti-Hirayama model. The concentration-dependent luminescence quenching was explained by the non-radiative energy transfer process between the Sm 3+ ions through the cross-relaxation mechanism. The CIE chromaticity coordinates and correlated color temperatures for Tb 3+ /Sm 3+ co-doped lead borate glasses are also presented and discussed. [ABSTRACT FROM AUTHOR]

In present work, thermal, structural and optical properties of un-doped Li 2 MgGeO 4 and lanthanide - doped Li 2 MgGeO 4 :Ln3+ (Ln = Er, Ho) germanate ceramics have been studied. Based on DSC measurements, two reversible phase transitions were verified during heating and cooling process of germanate ceramics. The results obtained from the Rietveld refinement indicate that Li 2 MgGeO 4 ceramics crystallize in monoclinic crystal lattice. Structural aspects were also evidenced by Raman and infrared spectroscopy. Emission investigations indicate that the most intense green bands due to the 4S 3/2 → 4I 15/2 (Er3+) and 5F 4 ,5S 2 → 5I 8 (Ho3+) transitions are well overlapped with broad band located near 500 nm. Broad green emission is attributed with the presence of magnesium in ceramic matrix. Based on literature data it can be assigned to F-type centers. • un-doped and lanthanide doped germanate ceramics have been studied. • Li 2 ZnGeO 4 ceramics crystallize in a monoclinic crystal lattice. • Intensive emission is due to 4S 3/2 → 4I 15/2 (Er3+) and 5F 4 ,5S 2 → 5I 8 (Ho3+) transitions. • Emission bands of Ln3+ are overlapped with broad green band of ceramic matrix. • Broad green emission is due to presence of magnesium and assigned to F-type centers. [ABSTRACT FROM AUTHOR]

The near-infrared luminescence properties of Pr3+/Yb3+: PLZT ferroelectric ceramics have been examined for the first time. Independently, upon either 450 nm (Pr3+) or 980 nm (Yb3+) excitation, luminescence centered at 1340 nm was observed, which corresponds to the 1G4→3H5 transition of Pr3+. Several spectroscopic parameters for the 1G4→3H5 transition of Pr3+ ions were determined. The average product of emission cross section and radiative lifetime were relatively large for all x/65/35 PLZT samples ( x=6-10) studied, with values close to 105±2 (×10−26 cm2·s). These spectroscopic investigations indicate that Pr3+/Yb3+: PLZT ferroelectric ceramics are promising candidate for efficient sources emitting near-infrared radiation at 1340 nm. [ABSTRACT FROM AUTHOR]

Er 3+ /Yb 3+ co-doped lead germanate glasses have been examined for up-conversion luminescence temperature sensors. Up-conversion luminescence spectra corresponding to 2 H 11/2 → 4 I 15/2 and 4 S 3/2 → 4 I 15/2 transitions of Er 3+ are changed with temperature. The fluorescence intensity ratio (FIR) and temperature sensitivity were determined. The maximum sensitivity is found to be 70 × 10 −4 K −1 at T = 550 K in the temperature range of 300–600 K. It suggests that Er 3+ /Yb 3+ co-doped lead germanate glass is promising for optical temperature sensors. [ABSTRACT FROM AUTHOR]

Up-conversion luminescence spectra of Er 3+ ions in PbO–Ga 2 O 3 –GeO 2 and PbO–Ga 2 O 3 –SiO 2 glasses have been examined as a function of temperature in the 298–650 K range. The relative emission intensities of green bands corresponding to 2 H 11/2 → 4 I 15/2 and 4 S 3/2 → 4 I 15/2 transitions of Er 3+ were determined with temperature. Based on up-conversion luminescence spectra of Er 3+ , the fluorescence intensity ratio and temperature sensitivity for glasses based on PbO–Ga 2 O 3 –XO 2 (X = Ge, Si) were calculated. The maximum sensitivity is equal to 20.4 × 10 − 4 K − 1 at T = 620 K (X = Ge) and 26.4 × 10 − 4 K − 1 at T = 590 K (X = Si) suggesting potential application in optical sensor thermometry. [ABSTRACT FROM AUTHOR]

Luminescence properties of Pr 3+ ions in germanate glasses modified by BaF 2 were investigated. Several luminescence bands originating to transitions from the 3 P 0 state to the lower-lying states of Pr 3+ were registered under 450 nm excitation. The spectral analysis suggests that the positions of luminescence bands and their relative intensities are changed significantly with BaF 2 content. The relative integrated luminescence intensities of 3 P 0 → 3 H 4 transition (blue) to the 3 P 0 → 3 F 2 transition (red) of Pr 3+ ions strongly depend on fluoride modifier BaF 2 in glass composition. The luminescence bands of Pr 3+ ions are shifted to shorter wavelengths with increasing BaF 2 content. [ABSTRACT FROM AUTHOR]

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]

• Pr3+/Er3+ co-doped glass based on InF 3 have been studied • Emission spectra of Pr3+/Er3+ were measured under different excitation wavelengths • Energy transfer process from Pr3+ to Er3+ occurs • Pr3+/Er3+ co-doped glass based on InF 3 are promising for white light emission Pr3+/Er3+ co-doped glasses based on InF 3 were synthesized and then studied for white light emission. The emission spectra consist of several bands corresponding to characteristic 4f-4f electronic transitions of Pr3+ and Er3+ ions. The relative intensities of emission bands depend on the selective excitation wavelengths. The energy transfer process from Pr3+ to Er3+ ions was confirmed by the excitation and emission spectra measurements. From emission spectra, the CIE chromaticity coordinates, the correlated color temperature (CCT) and the color purity (CP) were determined. The results indicate that Pr3+/Er3+ co-doped glasses based on InF 3 are excellent fluoride candidate to achieve warm white light emission. Graphical Abstract [Display omitted]. [ABSTRACT FROM AUTHOR]

Thermal, structural and optical properties of lead phosphate glasses containing Er 3+ ions have been studied as a function of PbF 2 concentration. Incorporation of PbF 2 results in structural and spectroscopic changes around Er 3+ ions and surrounding ligands, which were analyzed in detail using by DSC, XRD, absorption and luminescence spectroscopy. Especially, near-infrared luminescence spectra due to main 4 I 13/2 - 4 I 15/2 laser transition of Er 3+ ions are presented and discussed with PbF 2 content. Based on decay curve measurements the 4 I 13/2 luminescence lifetime of Er 3+ was determined and its value is found to be maximum at 18 mol% of PbF 2 . [ABSTRACT FROM AUTHOR]

Spectroscopic properties of rare earths in lead-free oxyfluoride germanate glasses were studied. The absorption and luminescence spectra of Eu 3+ , Pr 3+ and Er 3+ ions were examined as a function of BaF 2 concentration and several spectroscopic parameters for rare earths were determined. The ratio of integrated luminescence intensity of the 5 D 0 → 7 F 2 transition to that of the 5 D 0 → 7 F 1 transition of Eu 3+ decrease significantly with increasing BaF 2 content. The absorption (Er 3+ ) and emission (Pr 3+ ) ‘hypersensitive transitions’ of rare earths are shifted in direction to shorter wavelengths with increasing BaF 2 content in glass composition. Emission spectra and their decays corresponding to the main 4 I 13/2 → 4 I 15/2 laser transition of Er 3+ were also analyzed. Quite long-lived NIR luminescence of Er 3+ is observed for lead-free glass samples with low BaF 2 concentration. [ABSTRACT FROM AUTHOR]

Spectroscopic properties of Er 3+ ions in lead-free oxyfluoride germanate glasses were studied. The absorption and luminescence spectra of Er 3+ ions were examined for glass samples with low and high BaF 2 content. From absorption spectra the bonding parameter was calculated and its value is reduced with increasing BaF 2 content. The maximum of absorption peak due to 4 I 15/2 − 2 H 11/2 hypersensitive transition is shifted to shorter wavelengths (blue shift) with increasing BaF 2 content. Luminescence spectra and their decays corresponding to main 4 I 13/2 − 4 I 15/2 laser transition of Er 3+ are also presented and discussed. Quite long-lived near-infrared luminescence of Er 3+ is observed for lead-free glass samples with low BaF 2 concentration. [ABSTRACT FROM AUTHOR]

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]

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]

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]

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: 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: 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]

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]

Heavy metal oxide and oxyfluoride lead silicate glasses doped with rare-earth ions were prepared. Next, they were heat treated in order to obtain transparent glass-ceramics. The rare-earths as optically active ions were limited to trivalent Eu3+ and Dy3+. Correlation between the local structure and the luminescence properties of Eu3+ and Dy3+ ions in the studied glass and glass-ceramic systems was examined using X-ray diffraction, FT-IR and optical measurements. Especially, the ratio of integrated emission intensity of the 5D0--7F2 transition to that of the 5D0--7F1 transition of Eu3+, defined as the luminescence intensity ratio R (Eu3+) as well as the ratio of integrated emission intensity of the 4F9/2--6H13/2 transition to that of the 4F9/2--6H15/2 transition of Dy3+, defined as the luminescence intensity ratio Y/B (Dy3+), have been analyzed in details. Their values are reduced due to part incorporation of rare-earth ions into cubic β-PbF2 crystalline phase. The excitation and luminescence spectra of rare-earth ions in glass samples before and after heat treatment are presented and discussed in relation to potential application in optoelectronics. [ABSTRACT FROM AUTHOR]

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]

Dy-doped borate glasses with PbO and PbX2 (X = F, Cl) were examined using Raman and luminescence spectroscopy. The Raman spectra show the structural changes of a glass network with B2O3/PbO ratios and presence of PbX2 (X = F or Cl). The photoluminescence spectra measured in the visible range present two bands located at 480 and 573 nm, which correspond to 4F9/2-6H15/2 (blue) and 4F9/2-6H13/2 (yellow) transitions of Dy3+. Luminescence decays from the 4F9/2 state and yellow/blue luminescence intensity ratios (Y/B) were analyzed as a function of glass composition (B2O3/PbO) and PbX2 (X = F, Cl) content. The branching ratios of yellow/blue luminescence increase, whereas the 4F9/2 lifetime of Dy3+ ions decreases with increasing PbO concentration. An introduction of PbX2 to the borate glass results in the increasing of 4F9/2 lifetime and decreasing of the yellow-to-blue luminescence intensity ratio. These phenomena are related to reduction of covalency between Dy3+ and O2−/X− ions. [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: 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]

Abstract: Novel oxychloroborate glasses containing Nd3+ ions in the B2O3–PbCl2–PbO–Al2O3–WO3 system were investigated. The results on synthesis, short-range order structure and luminescent properties are reported. The influence of the PbCl2 content on the glass properties was analyzed. The near-infrared luminescence lines at 0.91, 1.06 and 1.33μm were registered in oxychloride lead borate glasses, which correspond to the transitions from the 4F3/2 state to the 4I9/2, 4I11/2 and 4I13/2 low-lying states of the Nd3+ ions. Luminescence decays from the 4F3/2 state were analyzed, in details. The effect of OH− content on the 4F3/2 lifetime of Nd3+ is much stronger than decreasing of phonon energy of the host. Consequently, the measured 4F3/2 lifetime of Nd3+ slightly decreases with the increasing of PbCl2 concentration. [Copyright &y& Elsevier]

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]

Abstract: Multicomponent fluoride glasses with relatively high IR transparency have been prepared. These glasses have IR cut-off (above 20μm) at longer wavelength than other fluoride type-glassy systems. The light transmission is about 80% at wavelengths up to 15μm in the InF3-based system doped with Er3+ ions. This suggests the possibility to obtain optical fiber for coupling to infrared emitting sources such as the CO2 laser, for optical applications. The emission spectra have been recorded at room temperature. Four emission bands centered at 976, 847, 668 and 550nm correspond to the 4I11/2–4I15/2, 4S3/2–4I13/2, 4F9/2–4I15/2 and 4S3/2–4I15/2 transitions of erbium ions, respectively. The inhomogeneous transition linewidths of Er3+ ions in fluoroindate glass have been investigated after heat treatment. Increased heating time increases the observed linewidth. This effect is related to the formation of several crystalline phases in this multicomponent system during heat treatment. However, spectral line narrowing has been detected under conditions of short time heating in comparison to an unheated sample. [Copyright &y& Elsevier]

The effect of erbium concentration on thermal stability and quantum efficiency of excited states was studied using DSC, XRD and optical methods. A large value of stability parameter ΔT close to 118 °C has been obtained for fluoroindate glass singly doped with 2 mol% of erbium ions. With increasing erbium concentration stability parameter extremely decreased and several crystalline peaks appeared, what was stated by X-ray diffraction. Also, the strong luminescence quenching is observed. This behavior is consistent with nonradiative processes related to the Er–Er interaction. [Copyright &y& Elsevier]

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]

Abstract: Luminescence properties of Dy3+–Tb3+ co-doped lead borate glasses were investigated. Luminescence spectra were registered under various excitation wavelengths. Characteristic luminescence bands corresponding to transitions of Dy3+ and Tb3+ ions were detected under excitation of trivalent dysprosium. The energy transfer from Dy3+ to Tb3+ ions in lead borate glass occurs through a nonradiative process with an efficiency up to 16%. The presence of energy transfer process was also confirmed by excitation spectra measurements. [Copyright &y& Elsevier]

Inorganic glasses co-doped with rare-earth ions have a key potential application value in the field of optical communications. In this paper, we have fabricated and then characterized multicomponent TiO2-modified germanate glasses co-doped with Yb3+/Ln3+ (Ln = Pr, Er, Tm, Ho) with excellent spectroscopic properties. Glass systems were directly excited at 980 nm (the 2F7/2 → 2F5/2 transition of Yb3+). We demonstrated that the introduction of TiO2 is a promising option to significantly enhance the main near-infrared luminescence bands located at the optical telecommunication window at 1.3 μm (Pr3+: 1G4 → 3H5), 1.5 μm (Er3+: 4I13/2 → 4I15/2), 1.8 μm (Tm3+: 3F4 → 3H6) and 2.0 μm (Ho3+: 5I7 → 7I8). Based on the lifetime values, the energy transfer efficiencies (ηET) were estimated. The values of ηET are changed from 31% for Yb3+/Ho3+ glass to nearly 53% for Yb3+/Pr3+ glass. The investigations show that obtained titanate–germanate glass is an interesting type of special glasses integrating luminescence properties and spectroscopic parameters, which may be a promising candidate for application in laser sources emitting radiation and broadband tunable amplifiers operating in the near-infrared range. [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]

Fluoroindate glasses co-doped with Pr3+/Er3+ ions were synthesized and their near-infrared luminescence properties have been examined under selective excitation wavelengths. For the Pr3+/Er3+ co-doped glass samples several radiative and nonradiative relaxation channels and their mechanisms are proposed under direct excitation of Pr3+ and/or Er3+. The energy transfer processes between Pr3+ and Er3+ ions in fluoroindate glasses were identified. In particular, broadband near-infrared luminescence (FWHM = 278 nm) associated to the 1G4 → 3H5 (Pr3+), 1D2 → 1G4 (Pr3+) and 4I13/2 → 4I15/2 (Er3+) transitions of rare earth ions in fluoroindate glass is successfully observed under direct excitation at 483 nm. Near-infrared luminescence spectra and their decays for glass samples co-doped with Pr3+/Er3+ are compared to the experimental results obtained for fluoroindate glasses singly doped with rare earth ions. [ABSTRACT FROM AUTHOR]

The effect of oxide modifiers on multiple properties (structural and spectroscopic) of phosphate glasses with molar composition 60P2O5-(10−x)Ga2O3-30MO-xEu2O3 and 60P2O5-(10−y)Ga2O3-30MO-yEr2O3 (where M = Ca, Sr, Ba; x = 0, 0.5; y = 0, 1) were systematically examined and discussed. The local structure of systems was evidenced by the infrared (IR-ATR) and Raman spectroscopic techniques. The spectroscopic behaviors of the studied glass systems were determined based on analysis of recorded spectra (excitation and emission) as well as luminescence decay curves. Intense red and near-infrared emissions (1.5 μm) were observed for samples doped with Eu3+ and Er3+ ions, respectively. It was found that the value of fluorescence intensity ratio R/O related to 5D0→7F2 (red) and 5D0→7F1 (orange) transition of Eu3+ ions depends on the oxide modifiers MO in the glass host. However, no clear influence of glass modifiers on the luminescence linewidth (FWHM) was observed for phosphate systems doped with Er3+ ions. Moreover, the 5D0 and 4I13/2 luminescence lifetimes of Eu3+ and Er3+ ions increase with the increasing ionic radius of M2+ (M = Ca, Sr, Ba) in the host matrix. The obtained results suggest the applicability of the phosphate glasses with oxide modifiers as potential red and near-infrared photoluminescent materials in photonic devices. [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]