The effect of modifiers on the fluorescence and life-time of Gd3+ ions doped in borate glasses.

The effect of glass modifiers on the fluorescence and life time of the 6P(7/2) energy state of the Gd3+ ion has been investigated. A shift in the energy of maximum of the fluorescence has been observed. The results are explained on the basis of the relative cation and anion field strengths due to modifiers. A variation in the life-time of the 6P7.2 energy state of the Gd3 ion has also been noted.     

Thermo-optical characteristics and concentration quenching effects in Nd3+ doped yttrium calcium borate glasses

In this work we present a comprehensive study of the spectroscopic and thermo-optical properties of a set of samples with composition xNd(2)O(3)-(5-x)Y(2)O(3-)40CaO-55B(2)O(3) (0 ≤ x ≤ 1.0 mol%). Their fluorescence quantum efficiency (η) values were determined using the thermal lens technique and the dependence on the ionic concentration was analyzed in terms of energy transfer processes, based on the F?rster-Dexter model of multipolar ion-ion interactions. A maximum η = 0.54 was found to be substantially higher than for yttrium aluminoborate crystals and glasses with comparable Nd(3+) content. As for the thermo-optical properties of yttrium calcium borate, they are comparable to other well-known laser glasses. The obtained energy transfer microparameters and the weak dependence of η on the Nd(3+) concentration with a high optimum Nd(3+) concentration put this system as a strong candidate for photonics applications.     

Study on Gd3+ and Sm3+ co-doped ceria-based electrolytes

Doped ceria electrolytes of Ce_1-aGd_a-ySm_yO_2–0.5a, wherein a=0.15 or 0.2, and 0ya, were prepared with the citrate method, and characterized by inductively coupled plasma–atomic emission spectrometry, energy dispersive spectrometry, scanning electron microscopy, powder X-ray diffraction, and AC impedance spectroscopy. The effect of composition on the structure and conductivity was studied. All the samples were fluorite-type ceria-based solid solutions. For the singly doped samples, the optimal composition was Ce_0.85Gd_0.15O_1.925 for Gd³⁺-doped ceria (CGO), which showed higher ionic conductivity than the best Sm³⁺-doped ceria (CSO) at 773–973 K. For the co-doped samples, the ionic conductivities were higher than those of the singly doped ones in the temperature range 673–973 K when a=0.15, but only better in 673–773 K when a=0.2. For the samples of Ce_0.85Gd_0.15-ySm_yO_1.925, wherein 0.05y0.1, much higher ionic conductivity was observed than those of the singly doped ceria at 773K~973 K. Therefore, these co-doped samples would be better than CGO and CSO to be the electrolytes of intermediate-temperature solid oxide fuel cells.     

Energy transfer between Er3+:Sm3+codoped TeO2-Li2O glass

The energy transfer in Er3+: Sm3+ codoped binary TeO2-Li2O (TLO) glass has been studied using 532 nm laser radiation on the basis of fluorescence intensity and the lifetime measurements. It is observed that the trace of erbium ion can be utilized to sensitize the samarium. The mechanism involved in the present case is found to be dipole-dipole. The energy transfer efficiencies, probabilities of energy transfer and the average donor acceptor distance has been evaluated.     

Energy transfer from UO22+ to Sm3+ in phosphate glass

Energy transfer from UO₂²⁺ to Sm³⁺ is described. The transfer efficiencies are calculated from the decrease of donor luminescence and lifetimes and from the increase of the acceptor fluorescence. It is shown that the transfer is nonradiative. The energy transfer efficiencies are greater when the donor is excited at higher energy levels due to stronger overlap between electronic levels of donor UO₂²⁺ and acceptor Sm³⁺. From the comparison of energy transfer efficiencies from UO₂²⁺ to Sm³⁺ and Eu³⁺ it is deduced that the overlap between excitation levels of donor and acceptor is a sufficient condition for the transfer.     

Optical transitions of Sm3+ in oxide glasses

Eigenvectors of the 4f⁵ electronic configuration of Sm³⁺ were calculated in intermediate coupling, and used to obtain the reduced matrix elements U^(λ). Absorption spectra of Sm³⁺ were recorded in phosphate, borate, germanate and tellurite glasses. The Judd-Ofelt $\text{Ω}{}_{\mathrm{\lambda }}\text{'}\text{s}$ intensity parameters were then deduced from the measured oscillator strengths by least-squares fitting. Radiative transition probabilities and integrated cross-sections of stimulated emissions are obtained. Calculated branching ratios and decay lifetimes are compared with the experimental values.     

Judd-Ofelt intensity parameters and spectral properties of Gd2O3:Eu3+ nanocrystals

Three nonequivalent centers of Cs (A, B, and C) in monoclinic phase and C2 and S6 centers in cubic phase were identified in the Gd2O3:Eu3+ nanocrystals with spectral techniques. Size dependence in the spectra indicated that the excitations from both host and charge-transfer band (CTB) for the 5D0 --> 7F2 transition of Eu3+ ions were nearly equal for a larger size of 135 nm of the cubic phase; however, with decreasing the size to or less than 23 nm, the excitations by the CTB dominated. The variation of excitation leading to the symmetry and energy change in the C2 and S6 sites was also observed for larger particle sizes. The Judd-Ofelt intensity parameters Omega(lambda) (lambda = 2, 4) for Gd2O3:Eu3+ nanoparticles were experimentally determined. The parameters Omega(lambda) were found to significantly change with the sizes of Gd2O3:Eu3+ from nanoparticles to bulk material. With decreasing the size from 135 to 15 nm, the quantum efficiencies for 5D0 reduced from 23.6% to 4.6% due to the increasing ratio of surface to volume.     

Optical characteristics and intensity parameters of Sm3+ in GeO2, ternary germanate,and borate glasses

Absorption and fluorescence spectra of Sm3+ were measured in GeO₂, ternary germanate, and borate glasses. From these the intensity parameters were calculated by use of the Judd-Ofelt formula.Visible emission and decay times from the⁴G_5/2 level and its relative quantum efficiencies were measured The quantum efficiencies (QE) of the fluorescence in ternary germanate was higher by a factor of 20 than in GeO₂, The small QE in GeO₂, is explained by cross-relaxation between neighboring Sm³⁺ ions. The later process in hindered by the change in glass structure in the presence of modifier ions. A similar effect is observed in other glasses such as borate, where the addition of modifiers increases the QE of fluorescence.     

Energy transfer between Bi3+ and Nd3+ in germanate glass

Energy transfer from Bi³⁺ to Nd³⁺ is reported in germanate glass. It was found that the excitation range and intensities of the ⁴F_{$\text{3}\text{2}$} → ⁴I_{$\text{9}\text{2}$}, ⁴I_{$\text{11}\text{2}$} emissions are increased several fold when excited through ¹S₀ → ³P₁ absorption of Bi³⁺. It is shown that the energy transfer is nonradiative. The energy transfer probability and efficiency were calculated from the Bi³⁺ fluorescence decay rates and intensities. The Bi³⁺ → Nd³⁺ energy transfer may be utilized in Nd³⁺ glass laser.     

Quantum yield of Ce3+ and energy transfer between Ce3+ and Tb3+ in borax glasses

Quantum yields of Ce³⁺ in borax glasses were obtained by the comparative method and by lifetime measurements. Energy transfer from Ce³⁺ to Tb³⁺ was detected in borax glasses from the excitation spectrum. The transfer probabilities were calculated from the increase in the Tb³⁺ fluorescence in the presence of Ce³⁺ and the decrease of the Ce³⁺ fluorescence in the presence of Tb³⁺. A linear dependence of the transfer probabilities was found with the squared sum of the concentrations of the donor and acceptor ions. This is consistent with dipolar mechanism and interactions of one Ce³⁺ donor with two Tb³⁺ acceptors, in view of the Fong-Diestler theory.     

Energy transfer between Bi3+ and Eu3+ in germanate glasses using time resolved spectroscopy

Energy transfer between Bi³⁺ and Eu³⁺ is shown to consist of radiative and non-radiative processes. The temperature effect on the equilibrium between ³P₀ and ³P₁ levels resulting in the change of spectral overlap determines the probability of the non-radiative transfer.     

Energy transfer between samarium and europium in phosphate glasses

A study of energy transfer from samarium to europium in phosphate glasses was performed for a range of donor and acceptor concentrations corresponding to a donor-acceptor distance of 13–24 Å. The energy transfer probabilities were calculated. The mechanism of transfer was deduced by fitting the experimental decay curves to the theoretical curves obtained by Inokuti and Hiroyama. Theoretical transition probabilities based on Dexter's formula were calculated. It was inferred that the energy is transferred by a dipole-quadrupole mechanism which is assisted by phonons. It was possible to indicate the path by which the transfer takes place.     

Energy transfer between dyes on glass surfaces and ions in glasses

A method for radiative and non-radiative energy transfer between flourescent organic dyes incorporated in a thin film deposited on a glass and inorganic ions in the bulk or surface of the glass is proposed.     

Spectroscopic characteristics of Sm3+-doped alkali fluorophosphate glasses

Optical absorption, luminescence and lifetime measurements of Sm(3+)-doped alkali fluorophosphate glasses with molar compositions of 50(NaPO(3))(6)+10TeO(2)+20AlF(3)+19RF+1Sm(2)O(3) (R=Li, Na and K) are described. The variation of optical properties with glass composition plays a dominant role in the determination of efficient laser materials. From the experimental oscillator strengths of f-f electric dipole transitions, the phenomenological Judd-Ofelt parameters have been evaluated and are used to evaluate radiative parameters such as radiative transition probabilities (A(R)), branching ratios (beta(R)), lifetimes (tau(R)) and integrated absorption cross-section (sigma(a)) for various excited levels. The predicted values of tau(R) and beta(R) from the (4)G(5/2) excited level to its lower levels are compared with the experimentally measured values. Stimulated emission cross-sections (sigma(e)) were also determined for (4)G(5/2)-->(6)H(J) (J=5/2, 7/2, 9/2 and 11/2) emission transitions. From the emission transitions of Sm(3+) in these alkali tellurofluorophosphate glasses certain potential laser transitions have been identified.     

Optical characterization of Sm3+ and Dy3+:ZnO-PbO-B2O3 glasses

Here, we present the results of the analysis of Sm(3+) or Dy(3+) (0.5 mol%) ions doped heavy metal oxide (HMO)-based zinc lead borate (ZLB) glasses. Optical measurements such as absorption, emission spectra, lifetimes, XRD, DSC profiles have been carried out. The emission spectrum of Sm(3+):ZLB has shown the emission transitions of (4)G(5/2)-->(6)H(5/2) (563 nm), (4)G(5/2)-->(6)H(7/2) (598 nm), (4)G(5/2)-->(6)H(9/2) (646 nm), (4)G(5/2)-->(6)H(11/2) (708 nm) with lambda(exc): 401 nm ((6)H(5/2)-->(4)F(7/2)). In the case of the Dy(3+):ZLB glass, emission transitions of (4)F(9/2)-->(6)H(15/2) (485 nm), (4)F(9/2)-->(6)H(13/2) (575 nm) and (4)F(9/2)-->(6)H(11/2) (664 nm) with lambda(exi): 447 nm ((6)H(15/2)-->(4)I(15/2)) have been identified. Energy level schemes relating to the emission mechanisms involved in Sm(3+) and Dy(3+) glasses have been given.     

Optical characterization of Eu3+ and Tb3+ ions doped zinc lead borate glasses

This paper reports on the spectral analysis of Eu3+ or Tb3+ ions (0.5 mol%) doped heavy metal oxide (HMO) based zinc lead borate glasses from the measurement of their absorption, emission spectra and also different physical properties. From the XRD, DSC profiles, the glass nature and glass thermal properties have been studied. The measured emission spectrum of Eu3+ glass has revealed five transitions (5D0-->7F0, 7F1, 7F2, 7F3 and 7F4) at 578, 591, 613, 654 and 702 nm, respectively, with lambdaexci=392 nm (7F0-->5L6). In the case of Tb3+:ZLB glass, four emission transitions such as (5D4-->7F6, 7F5, 7F4 and 7F3) that are located at 489, 542, 585 and 622 nm, respectively, have been measured with lambdaexci=374 nm. For all these emission bands decay curves have been plotted to evaluate their lifetimes and the emission processes that arise in the glasses have been explained in terms of energy level schemes.     

Luminescent properties of Tb3+ and Gd3+ ions doped aluminosilicate oxyfluoride glasses

Tb³⁺ and Gd³⁺ ions doped lithium–barium–aluminosilicate oxyfluoride glasses have been prepared. The transmission, emission and excitation spectra were measured. It has been found that those Tb³⁺-doped lithium–barium–aluminosilicate oxyfluoride glasses exhibit good UV-excited luminescence. The luminescence intensity of Tb³⁺ ion increases for those (Tb³⁺, Gd³⁺)-codoped glasses. Energy transfer process from Gd³⁺ ion to Tb³⁺ ion is indicated.     

The critical concentration for quenching of the Eu3+ luminescence in some Gd3+ : Eu3+ systems

The critical concentration for quenching of the Eu³⁺ luminescence is calculated theoretically for several Gd³⁺ : Eu³⁺ systems. A comparison is made with the experimental values. The results are discussed in terms of energy migration.     

多孔二氧化硅中Gd3+ → Eu3+的能量传递

通过水热反应法，获得了单掺和双掺Eu³⁺，Gd³⁺的多孔二氧化硅组装体，研究了掺杂体系的光谱特性，观察到Gd³⁺ → Eu³⁺的能量传递。分析了能量传递过程，探讨了在多孔二氧化硅中Gd³⁺→Eu³⁺的能量传递的机理，其机理主要为电偶极-电偶极相互作用。     

Effect of pH on the adsorption of Ce3+, Sm3+, Eu3+ and Gd3+ ions on activated charcoal

The adsorption of metal ions such as Ce³⁺, Sm³⁺, Eu³⁺ and Gd³⁺ ions on activated charcoal has been studied as a function of pH. The adsorption mechanism of these ions is discussed in terms of hydrolyzed species formed in aqueous solution at different pH.