Luminescence spectroscopy of rare earth-doped oxychloride lead borate glasses

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 ⁴S_3/2,²H_11/2-⁴I_15/2 and ⁴I_13/2-⁴I_15/2 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.     

Luminescence spectra and optical properties of TeO2-WO3-Li2O glasses doped with Nd, Sm and Er rare earth ions

New tellurite glass series of the form (70-x)TeO₂-20WO₃-10Li₂O-xLn₂O₃, where x=0, 1, 3 and 5 mol% and Ln=Nd, Sm and Er, were prepared. Density of the prepared glasses was measured and molar volume was calculated. Luminescence spectra of the prepared glasses were measured at room temperature using a micro-Raman spectrometer. The obtained luminescence intensity ratio was correlated with the rare earth ion concentration, the short distance between the identical rare earth ions r(Ln-Ln) and the glass density. Optical properties like refractive index, molar refractivity and optical polarizability were theoretically calculated in order to interpret the dependence of these properties on the rare earth ion content.     

Luminescent properties of Dy-doped and Dy–Tmco-doped phosphate glasses

Phosphate glasses doped with Dy³⁺ ions and co-doped with Dy³⁺–Tm³⁺ ions are successfully prepared in the present work. Their photoluminescence properties have been studied by absorption, excitation and emission spectra. A combination of blue and yellow emissions has emerged in the glasses, which allows the observation of white light when the glasses are excited by the ultraviolet light. The emission intensity of Dy³⁺ is influenced by the system ionicity, while the intensity ratio of yellow to blue emissions from Dy³⁺ can be tuned by varying both the concentration of Tm³⁺ ion and the glass matrix composition.     

Laser spectroscopy of rare earth ions in lead borate glasses and transparent glass-ceramics

Rare earth doped lead borate glasses and transparent glass-ceramics have been studied using optical spectroscopy. Based on the absorption, emission and its decay and the Judd-Ofelt calculations, several radiative and laser parameters for Ln ³⁺ (Ln = Pr, Nd, Eu, Dy, Er, Tm) were evaluated. The large values of luminescence lifetime, quantum efficiency of excited state and room temperature peak stimulated emission cross-section suggest efficient laser transitions of Ln ³⁺ ions in lead borate glasses. The obtained results indicate that lead borate glasses and glass-ceramics containing Ln ³⁺ ions are promising host matrices for solid-state laser applications.     

Emission characteristics of Dy3+ ions in lead antimony borate glasses

Glasses with the composition 30PbO–25Sb₂O₃–(45?x)B₂O₃–xDy₂O₃ for x=0 to 1 were prepared in steps of 0.2 by the melt-quenching method. Various physical parameters, viz., density, molar volume, and oxygen packing density, were evaluated. Optical absorption and luminescence spectra of all the glasses were recorded at room temperature. From the observed absorption edges optical band gap, the Urbach energies are calculated; the optical band gap is found to decrease with the concentration of Dy₂O₃. The Judd–Ofelt theory was applied to characterize the absorption and luminescence spectra of Dy³⁺ ions in these glasses. Following the luminescence spectra, various radiative properties, like transition probability A, branching ratio β and the radiative life time τ for different emission levels of Dy³⁺ ions, have been evaluated. The radiative lifetime for the ⁴F_9/2 multiplet has also been evaluated from the recorded life time decay curves, and the quantum efficiencies were estimated for all the glasses. The quantum efficiency is found to increase with the concentration of Dy₂O₃.     

Optical properties of lithium magnesium borate glasses doped with Dy and Sm ions

Several studies showed the interesting properties of trivalent lanthanide ions when doped in various types of glasses. Optical and physical properties of lithium magnesium borate glasses doped with Dy³⁺ then with Sm³⁺ ions were determined by measuring their absorption and luminescence spectra in the visible region. The absorption spectra of Dy³⁺ showed eight absorption bands with hypersensitive transition at 1265 nm (⁶H_15/2→⁶F_11/2-⁶H_9/2) and three PL emission bands at 588 nm (⁴F_9/2→⁶H_15/2), 660 nm (⁴F_9/2→⁶H_13/2) and 775 nm (⁴F_9/2→⁶H_11/2). Regarding the Sm3⁺, nine absorption bands were observed with hypersensitive transition at 1237 nm (⁶H_5/2–⁶F_7/2); the PL spectrum showed four prominent peaks at ⁴G_5/2→⁶H_5/2 (yellow color), ⁴G_5/2→⁶H_7/2 (bright orange color), ⁴G_5/2→⁶H_9/2 (orange reddish color) and ⁴G_5/2→⁶H_11/2 (red color), respectively. Finally, a series of physical parameters such as the oscillator strengths, refractive index, ions concentration, Polaron radius and other parameters were calculated for each dopant.     

Luminescence properties of Tb doped and Tm/Tb/Sm co-doped glasses for LED applications

Tb³⁺ ions doped and Tm/Tb/Sm co-doped glasses for light-emitting-diodes (LED) applications have been synthesized by melt quenching method. Their photoluminescence properties were studied by emission and excitation spectra. The ⁵D₃ and ⁵D₄ emission of Tb³⁺ can be varied by adjusting Tb³⁺ concentrations and the compositions of glass matrix. Blue, green and reddish orange emission bands were observed in the emission spectra of Tm/Tb/Sm co-doped glasses. The combination of these emission bands allows the realization of white light when the glasses are excited by near ultraviolet light. In addition, the relative intensity ratios of respective emission lines are dependent on the composition of glasses and the excitation wavelength.     

Pulsed-laser deposition of smooth thin films of Er, Pr and Nd doped glasses

Thin films of complex oxides have been obtained by pulsed-laser deposition (PLD) from glass targets belonging to the system Li₂O-Al₂O₃-P₂O₅-(RE)₂O₃, with RE = Nd, Pr, Er. The films were deposited on quartz, silicon and ITO/glass substrates using a F₂ laser (λ = 157 nm, ι ≈ 20 ns) for ablation in vacuum. The structural, morphological and optical properties of the oxide films were investigated through IR and UV-VIS spectroscopy, Atomic Force Microscopy (AFM), Scanning Electron Microscopy, Energy Dispersive X-ray Spectroscopy (SEM-EDX) and Spectroscopic Ellipsometry. The laser wavelength was found to be the key parameter to obtain thin films with very smooth surface. In this way new possibilities are opened to grow multilayer structures for photonic applications.     

Compositional-dependent lead borate based glasses doped with Eu ions: Synthesis and spectroscopic properties

New multicomponent lead borate based glasses with various PbO/B₂O₃ weight ratio were prepared. The glass samples were analyzed in detail by using Raman and IR absorption spectroscopy. Optical properties of Eu³⁺ ions have been investigated in lead borate based systems, in which PbO/B₂O₃ weight ratios were changed from 1:2 to 8:1 in glass composition. The values of the phonon energy of the host and ⁵D₀ lifetime of Eu³⁺ decrease, whereas absorption and emission intensities, as well as bonding parameter increase with increasing PbO concentration. Additionally, spectral lines are shifted in direction to the lower frequency region. Non-monotonic dependence of the fluorescence intensity ratio R (⁵D₀-⁷F₂/⁵D₀-⁷F₁) upon PbO/B₂O₃ content has been observed in contrast to bonding parameter that is also non-linear but monotonic. Some structural and spectroscopic aspects for Eu-doped lead borate based glasses are presented.     

Synthesis and characterization of holmium oxide doped cadmium lead borate glasses

Holmium doped cadmium lead borate glasses were prepared from melting in appropriate proportions of a mixture of CdO, PbO₂, H₃BO₃ and (1–2 mol %) Ho₂O₃ in the temperature range of 800–850 °C. The density of glass samples was measured using Archimedes Principle. The infrared spectra of the glasses in the range of 400–4000 cm^?1 showed their structure systematically. No boroxol ring formation was observed in the structure of these glasses, but the conversion of 3-fold to 4-fold coordination of boron atoms in the structure of glasses was observed. The glass transition studies were done through differential scanning calorimetry. The optical analysis is done by using the Judd–Ofelt theory.     

Spectroscopic and photoluminescence characteristics of Dy ions in lead containing sodium fluoroborate glasses for laser materials

Lead containing calcium zinc sodium fluoroborate (LCZSFB) glasses doped with different concentrations of trivalent dysprosium ions were prepared and investigated by the XRD, FTIR, optical absorption, photoluminescence and decay curve analysis. The experimentally determined oscillator strengths have been determined by measuring the areas under the absorption peaks and the Judd–Ofelt (J–O) intensity parameters were calculated using the least squares fit method. From the evaluated J–O parameters the radiative transition probability rates, radiative lifetimes and branching ratios were calculated for ⁴F_9/2 excited level. Room temperature photoluminescence spectra for different concentrations of Dy³⁺-doped LCZSFB glasses were obtained by exciting the glass samples at 386 nm. The intensity of Dy³⁺ emission spectra increases with increasing concentration of 0.1, 0.25, 0.5 and 1.0 mol% and beyond 1.0 mol% the concentration quenching is observed. The measuring branching ratios are reasonably high for transitions ⁴F_9/2→⁶H_15/2 and ⁶H_13/2, suggesting that the emission at 484 and 576 nm, respectively, can give rise to lasing action in the visible region. From the visible emission spectra, yellow–blue (Y/B) intensity ratios and chromaticity color coordinates were also estimated. The lifetimes of ⁴F_9/2 metastable state for the samples with different concentrations were also measured and discussed.     

Luminescence and laser transition studies of Dy:K-Mg-Al fluorophosphate glasses

Dysprosium ion doped fluorophosphate glasses with compositions of PKMAFDy: (56−x/2) P₂O₅+17K₂O+8Al₂O₃+(15−x/2)MgO+4AlF₃+xDy₂O₃ (x=0.01, 0.05, 0.1, 1.0 and 2.0 mol%) have been prepared by melt quenching technique and are characterized by optical absorption, emission spectra and fluorescence lifetime measurements. The observed bands in the absorption spectrum are analysed by using free-ion Hamiltonian (H_FI) model. The Judd-Ofelt (JO) analysis has been performed and the intensity parameters (Ω_λ, λ=2, 4, 6) have been evaluated that are used to predict radiative properties. From emission spectra, the effective bandwidth (Δλ_eff) and the stimulated emission cross-section (σ(λ_p)) were evaluated. The fluorescence decay from the ⁴F_9/2 level of Dy³⁺ ions have been measured by monitoring the intense ⁴F_9/2→⁶H_13/2 transition (573 nm). The lifetimes (τ) are found to decrease with increasing concentration due to concentration quenching. The decay curves are single exponential for lower concentrations and gradually changes to non-exponential for higher concentrations. The non-exponential decay curves are well fitted to the Inokuti-Hirayama (IH) model for S=6 which indicates that the energy transfer between the donor and acceptor is of dipole-dipole type. The systematic analysis on decay measurements reveals that the energy transfer mechanism strongly depends on concentration as well as glass composition.     

Luminescent studies of Dy ion in alkali lead tellurofluoroborate glasses

Dy³⁺-doped alkali lead tellurofluoroborate (RLTB) glasses (R=Li, Na and K) were prepared by melt quenching technique. Judd-Ofelt theory has been used to evaluate the three intensity parameters Ω₂, Ω₄ and Ω₆ from the experimental oscillator strengths. The photoluminescence spectra obtained by the excitation wavelength of 385 nm show four emission bands at 454, 483, 575 and 665 nm corresponding to the ⁴I_15/2→⁶H_15/2 and ⁴F_9/2→⁶H_J/2 (J=15/2, 13/2 and 11/2) transitions, respectively. The laser characteristic parameters like fullwidth at half maxima (FWHM), stimulated emission cross-sections (σ_e), optical gain parameters (σ_e×τ_exp) and gain bandwidth parameters (σ_e×FWHM) were determined. From the visible emission spectra, yellow to blue (Y/B) intensity ratios and chromaticity coordinates were also estimated. The lifetimes of ⁴F_9/2 metastable state were also measured and discussed.     

Ion sputtering of minerals and glasses: a first step to the simulation of solar wind erosion

Selected rockforming minerals (plagioclase, augite, olivine, ilmenite, silicate and metal phases of the meteorite “Brenham”) as well as silicate and phosphate glasses were irradiated with heavy ions (⁴He⁺, ¹⁴N+, ²⁰Ne⁺, ⁴⁰Ar+, ⁵⁶Fe+, Xe⁺ _nat) in the energy range of 50-130 keV in order to study ion-induced sputtering. Sputtering yields were measured independently by means of multiple beam interferometry and particle track autoradiography.

The theory of sputtering by Sigmund, modified by Smith, was used to convert experimental heavy ion sputtering yields to H⁺- and He⁺-sputtering yields of the same target. Taking into account solar wind irradiation conditions at the lunar surface, an estimate of lunar erosion rates due to solar wind sputtering is given for the targets studied.     

Optical characterization of Cu ion-doped zinc lead borate glasses

We have developed a new series of zinc lead borate (ZLB) glasses by varying ZnO content, to enhance UV transmission, in the chemical composition of xZnO-15PbO-(85−x)B₂O₃, where x=0, 5, 10, 15, 20, 25, 30, 35, 40 and 45 mol% ZnO. From the measurement of UV absorption spectra both the direct and indirect band gaps have been evaluated. Also different physical properties of a reference glass of 45ZnO-15PbO-40B₂O₃ have been studied. From the measurement of refractive indices at six different wavelengths, Cauchy's constants (A=1.578743209; and ) have been computed and a satisfactory correlation has been achieved between the theoretical and the experimental results. Absorption spectra of Cu²⁺(45−x)ZnO-15PbO-40B₂O₃ (where x=0.1, 0.2, 0.5 and 1.0 mol%) have shown two absorption bands at 428 nm (²B_1g→²E_g) and 777 nm (²B_1g→²B_2g). Emission spectra of (1.0 mol%) Cu²⁺:ZLB have revealed two emission transitions at 400 and 493 nm with excitations at 288 and 316 nm.     

EPR investigations of calcium phosphate glasses containing manganese ions

Glasses of the xMnO·(100−x)[yP₂O₅·CaO] systems, with y=1, 2, 3 and 0≤x≤50 mol% MnO were prepared and investigated by means of electron paramagnetic resonance (EPR). The local order in diamagnetic vitreous matrices could be revealed by the Mn²⁺ paramagnetic ions used in EPR experiments. In each systems corresponding to a particular value of y, the effect of increasing the MnO content in the samples was investigated. The structure of our glasses shows an evolution depending of MnO content from structural units involving Mn²⁺ ions in well defined vicinities, to structural units containing clustered manganese ions. The changes of the linewidth and the intensity of the resonance line centered at g_eff≈2.0 when the content of manganese ions are increasing revealed this evolution.     

Sc2O3:Ce nanocrystals: Fluorescence and its dependence on the surrounding gas pressure

The fluorescence spectra of nanocrystalline powder samples of Sc₂O₃:Ce³⁺ prepared by the sol-gel process were studied. The strong shift of the fluorescence spectra with the excitation wavelength was observed. The effect of the surrounding gaseous medium on 4f⁰5d¹→4f¹ fluorescence of Ce³⁺ ions in nanoparticles, discovered earlier in YAG:Ce³⁺, was also observed and studied in Sc₂O₃:Ce³⁺. The fluorescence intensity and the excitation power dependence of fluorescence dramatically depend on the pressure of the gaseous media.     

Upconversion Properties of Er3+/Yb3+ Co-doped TeO2–TiO2–K2O Glasses

The Er³⁺/Yb³⁺ co-doped TeO₂–TiO₂–K₂O glasses were prepared by conventional melting procedures, and their upconversion spectra were performed. The dependence of luminescence intensity on the ratio of Yb³⁺/Er³⁺ was studied, and the relationship between green upconversion luminescence intensity and Er³⁺ concentration is discussed in detail. The 546 nm green upconversion luminescence intensity is optimised in the studied glasses either when the Yb³⁺/Er³⁺ ratio is 25/1 and Er³⁺ concentration is 0.1 mol%, or when the Yb³⁺/Er³⁺ ratio is 10/1 and Er³⁺ concentration is 0.15 mol%. These glasses could be one of the potential candidates for LD pumping microchip solid-state lasers.     

稀土硼酸盐玻璃中Ce3+的光谱性质和荧光衰减

合成Ｃｅ＾３＋掺杂的稀土硼酸盐玻璃,测试了材料的激发和发射光谱及荧光衰减曲线。紫外光激发下,玻璃中的Ｃｅ＾３＋发射强的蓝紫光,光谱的荧光寿命的分析结果表明,Ｃｅ＾３＋在这种稀土硼酸盐玻璃中形成两种性质不同的发光中心。     

Optical spectra of Dy in KY3F10 and LiLuF4 crystalline fibers

Visible optical properties of two crystalline fibers (KY₃F₁₀ and LiLuF₄) doped with Dy³⁺ have been investigated. In particular, the room-temperature absorption spectra have been analyzed using the Judd–Ofelt theory and the intensity parameters have been obtained. A criterion suitable for determining the proper choice of the dopant composition to tailor the luminescence properties of the crystals is proposed.