Optical properties of Ho3+ doped oxyfluoroborate glass

Ho3+ doped oxyfluoroborate glasses have been prepared with different concentration of holmium. The absorption and the fluorescence spectra have been recorded and used to determine various optical parameters such as oscillator strength, Judd-Ofelt intensity parameters, electric dipole line strengths, transition probability, branching ratio, stimulated emission cross section etc. Lifetime of the 5S2 level has been measured and found to decrease with an increase of the rare earth concentration. Non-radiative transition probability and quantum efficiency of the radiative transitions have also been calculated.     

Optical properties of Dy3+ doped in oxyfluoroborate glass

Optical absorption, fluorescence and photoacoustic spectra of Dy3+ doped in oxyfluoroborate glass has been studied. Lifetime of 4F(9/2) level has been measured for different concentration of Dy3+. Effect of concentration quenching on the lifetime and the fluorescence yield has been observed and the mechanism of energy transfer discussed. The energy transfer from Pr3+ to Dy3+ has been observed and explained in a codoped glass containing Pr3+ + Dy3+.     

Optical properties of Er3+ ions doped in oxyfluoroborate glass

In this paper the Stark components of 4S(3/2), 2H(11/2) and 4I(15/2) levels of Er3+ ion doped in oxyfluoroborate glass have been resolved using laser excitation and fluorescence measurements. The lifetime of 4S(3/2) level as a function of Er3+ concentration in the glass host has also been measured. Concentration quenching due to interaction among rare earth ions and the mechanism responsible for the same has been elucidated. The Judd-Ofelt analysis of the absorption spectrum has also been carried out.     

Optical properties of Nd3+ ions doped in oxyfluoroborate glass

Laser induced excitation spectrum of the Nd3+ ions doped in oxyfluoroborate glass have been recorded. Stark components of different electronic states have been reported. Judd-Ofelt analysis has also been accomplished on the basis of ultraviolet-visible-near-infrared (UV-vis-NIR) absorption spectrum. Various radiative parameters such as electric dipole line strength, transition probability, life time of the various energy levels, branching ratio etc., have been estimated.     

Optical studies of Eu3+ ions doped in tellurite glass

Absorption and fluorescence spectra of Eu3+ ions doped in a tellurite glass have been recorded and analysed. Judd-Ofelt analysis has been done in order to calculate the different optical parameters such as oscillator strength, Judd-Ofelt intensity parameters, stimulated emission cross-section, transition probability, branching ratio, radiative lifetime, etc. Lifetime measurements of the 5D0 level as a function of Eu3+ concentration have been used to explore the concentration quenching process. The mechanism of quenching is found to be of a dipole-dipole type.     

Laser spectroscopic studies of Tb3+-doped oxyfluoroborate glass

Tb3+-doped oxyfluoroborate glasses have been prepared for different concentrations of Tb. The absorption, fluorescence and photoacoustic spectra of these have been recorded and studied. It is marked that the fluorescence intensity of different fluorescence transitions decreases with the increase of Tb ion concentration in the glass. This quenching at higher concentration is due to the energy transfer among the excited and nearest neighbor unexcited Tb ions in the glass. The lifetime measurement confirms it, as the lifetime of a particular state was found to decrease with the increase of Tb ion concentration in the glass. The mechanism of the energy transfer process was determined to involve quadrupole quadrupole interaction. We have also studied the energy transfer from Tb3+-->Pr3+ when both the rare earths are doped together in the glass. A decrease in the lifetime of the 5D4 level of Tb3+ with the increase of Pr3+ concentration confirms this.     

Optical properties of Sm3+ ions doped in tellurite glass

Judd-Ofelt analysis of Sm(3+) ions doped in a tellurite glass has been accomplished. Fluorescence and life-time measurements have been carried out using Ar(+) laser and excimer laser. Stark splitting has been observed in the upper and lower levels in fluorescence. The life-time of 4G(5/2) level as a function of Sm(3+) concentration has been measured. Concentration quenching and the mechanism responsible for the same have been found.     

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.     

Thermoluminescence studies of UV-irradiated Y2O3:Eu3+ doped phosphor

The present paper reports thermoluminescence (TL) glow curves of Eu³⁺-doped Y₂O₃ phosphor with different ultraviolet (UV) exposure times. The glow peak shows second-order kinetics of Eu³⁺-doped Y₂O₃, and corresponding kinetic parameters were evaluated using the peak shape method. Calculations of trap depth were carried out using different methods. The kinetics order, activation energy, and frequency factor were calculated. The recorded glow curve shifts towards higher intensity with longer UV exposure. The heating rate used for recording TL was 3.0 °C s^?1. Particle size and structure were verified by X-ray diffraction (XRD) pattern and morphology by scanning electron microscopy (SEM) imaging.     

Optical characterization of Eu3+ and Tb3+ ions doped cadmium lithium alumino fluoro boro tellurite glasses

This article reports on the development and spectral results of Eu(3+) and Tb(3+) ions doped cadmium lithium alumino fluoro boro tellurite (CLiAFBT) glasses in the following composition. 40TeO2-30B2O3-10CdO-10Li2O-10AlF3 (Hostglass) (40-x)TeO2-30B2O3-10CdO-10Li2O-10AlF3-xEu2O3 (40-x)TeO2-30B2O3-10CdO-10Li2O-10AlF3-xTb4O7 where x=0.25, 0.50, 0.75, 1.0, 1.25 mol%. Glass amorphous nature and thermal properties have been studied using the XRD and DSC profiles. From the emission spectra of Eu(3+):glasses, five emission transitions have been observed at 578 nm, 592 nm, 612 nm, 653 nm, 701 nm and are assigned to the transitions (5)D(0)→(7)F(0), (7)F(1,)(7)F(2), (7)F(3) and (7)F(4), respectively, with λ(exci)=392 nm ((7)F(0)→(5)L(6)). In case of Tb(3+):glasses, four emission transitions ((5)D(4)→(7)F(6,)(7)F(5), (7)F(4) and (7)F(3)) are observed at 488 nm, 543 nm, 584 nm and 614 nm, respectively, with λ(exci)=376 nm. Decay curves and energy level diagrams have been plotted to evaluate the life times and to analyze the emission mechanism.     

Optical properties of Dy3+ doped calibo glass on addition of lead oxide

The effects of PbO on optical properties of dysprosium doped calibo glass have been studied. The content of PbO in the glass has been varied from 0 to 60 mol%. The absorption and fluorescence spectra are analyzed in terms of the Judd-Ofelt theory. It is observed that the fluorescence yield is maximum for the glass containing 40 mol% PbO. The I-R absorption spectra of these glasses have also been recorded and interpreted in terms of changes in the structure of the glasses.     

Optical properties of Sm3+ doped calibo glass with addition of lead oxide

Optical absorption and fluorescence spectra of Sm3+ doped calibo glasses and the effects on these on addition of lead oxide have been recorded. The concentration of lead oxide has been varied from 0 to 30 mol%. The Judd-Ofelt intensity parameters Omegalambda (lambda=2, 4, 6) for f-f transitions in Sm3+ ions trapped in these glasses are calculated and their variation with increase in proportion of lead oxide has been discussed. It is observed from the fluorescence spectra that the intensity of fluorescence reaches a maximum when 20% of PbO is present. Stimulated emission cross-section is calculated and compared with its value for other lattices.     

Luminescence behavior of Eu3+ doped LaF3 nanoparticles

Europium-doped LaF3 nanoparticles have been prepared by the ionic reaction in the ethanol at 60 degrees C. From the XRD pattern of nanoparticles and the emission spectra of Eu3+ ions, it has been concluded that the Eu3+ ions could easily substitute the La3+ sites and the solid solution La(1-x)Eu(x)F3 can be synthesized. Due to very low phonon energies of LaF3 matrix, the 5D1 emission of Eu3+ ions in La(1-x)Eu(x)F3 nanoparticles can be observed at room temperature when doping concentration of Eu3+ ions is lower than 30 mol%. The quenching process of 5D1 emission can be attributed to cross-relaxation. Since clusters of Eu3+ ions and resonance energy transfer only occurs within one particle due to the hindrance by the particle boundary, the concentration quenching resulted from resonance energy transfer between neighboring Eu3+ ions occurs at higher Eu3+ concentrations in the Eu3+ doped LaF3 nanoparticles.     

Luminescence of Tb3+ and Eu3+ doped amorphous zinc benzoates

The Tb(3+) and Eu(3+) doped amorphous zinc benzoate were prepared. Their infrared absorption, emission and excitation spectra were measured. The luminescence mechanisms of Tb(3+) and Eu(3+) in the amorphous substrate were discussed. The bonding modes of OCO group to Zn(2+) ion have two of symmetric and asymmetric bridging bidentate. The energy of the S(1) pi,pi* excited state of benzene ring can be transferred to Tb(3+) and Eu(3+) ion, and results in characteristic emission from the 5D(4)-->(7)F(j) of Tb(3+) and 5D(0)-->(7)F(j) of Eu(3+), respectively.     

Revision of structural properties of GdBO3 nanopowders doped with Eu3+ ions through spectroscopic studies

Monoclinic Gd(1-x)Eu(x)BO(3) nanopowders were successfully synthesized using a modified Pechini method. The crystal structure of the prepared materials was revised and confirmed using several techniques such as: IR, XRD, TEM, Raman spectroscopy and EDX analysis. The obtained material was comprised of particles, consisting of parts with the average size 350 nm. The luminescence properties of the prepared phosphors with different concentrations of Eu(3+) ions were characterized by excitation and emission spectra and its kinetic decay. The Judd-Ofelt parameters (Ω(2), Ω(4)), quantum efficiency, η, and chromaticity coordinates were also calculated.     

Luminescence properties of Eu3+ doped CaMoO4 nanoparticles

When Eu(3+) ions occupy Ca(2+) sites of CaMoO(4), which has a body centered tetragonal structure with inversion symmetry, only the magnetic dipole transition ((5)D(0)→(7)F(1)) should be allowed according to Judd-Ofelt theory. Even if there are a few distortions in the Eu(3+) environment, its intensity should be more than that of the electric dipole transition ((5)D(0)→(7)F(2)). We report here the opposite effect experimentally and ascribe this to the polarizability effect of the MoO(4) tetrahedron, which is neighboring to EuO(8) (symmetric environment). The contribution of the energy transfer process from the Mo-O charge transfer band to Eu(3+) and the role of Eu(3+) over the surface of the particle could be distinguished when luminescence decay processes were measured at two different excitations (250 and 398 nm). Further, the luminescence intensities and lifetimes increase significantly with increasing heat-treatment temperature of the doped samples. This is attributed to the reduction of H(2)O from the surface of the particles and a non-radiative process after heat treatment.     

Preparation and structure refinement of Eu3+ doped CaMoO4 nanoparticles

The nanoparticles of CaMoO(4)?:?Eu(3+) (Eu(3+) = 0, 1, 3, 5, 7, 10 at. %) are prepared at low temperature (150 °C for 3 h) using urea hydrolysis in ethylene glycol. These are characterized by X-ray diffraction (XRD), infrared spectroscopy (IR) and transmission electron microscopy (TEM). From XRD study, it was found that the solubility limit of Eu(3+) ions at the Ca(2+) sites is up to 3 at. % and above this, phase segregation occurs. In combination with Rietveld analysis, its crystal structure was found to be tetragonal phase (space group I4(1)/a (88) and Z = 4 (number of CaMoO(4) formula units per unit cell). Unit cell parameters and bond distances are calculated. The average crystallite sizes of as-prepared, 500 and 900 °C heated samples are found to be 20, 35 and 70 nm, respectively. The lattice strain is found to be 0.003-0.005. From IR study, the bands at 820 and 441 cm(-1) are assigned to asymmetric stretching and bending vibrations of the MoO(4)(2-) tetrahedron, respectively. From TEM study, the shape of particle was found to be spherical. The high resolution TEM suggests a change in orientation of the crystal on annealing up to 900 °C.     

Eu3+/Tb3+和Eu3+/Pr3+共掺杂P(MMA-co-St)的荧光性能的研究

将不同荧光性能的铽(Tb)、镨(Pr)离子分别与铕(Eu)离子混合，以三异丙氧基稀土的形式掺杂P(MMA-CO-St)共聚物，研究Eu^3 ／Tb^3 和Eu^3 ／pr^3 共掺杂P(MMA-CO-St)的荧光性能的变化情况．结果表明，Eu^3 ／Tb^3 掺杂的P(MMA-CO-St)中，Tb^3 作为能量给予体，Eu^3 作为能量接受体，能量转移的结果使Eu^3 特征荧光显增强；Eu^3 ／pr^3 掺杂的P(MMA-CO-St)中，Eu^3 的能量向pr^3 转移，致使Eu^3 的特征荧光猝灭，pr^3 的荧光略为增强．     

Spectroscopic properties of Nd3+ doped transparent oxyfluoride glass ceramics

In this paper, the spectroscopic properties of Nd(3+) doped transparent oxyfluoride glass ceramics containing LaF(3) nano-crystals were systematically studied. The formation and distribution of LaF(3) nano-crystals in the glass matrix were investigated by X-ray diffraction (XRD) and transmission electron microscopy (TEM). Based on Judd-Ofelt theory, the intensity parameters Omega(t) (t=2, 4, 6), spontaneous emission probability, radiative lifetime, radiative quantum efficiency, width of the emission line and stimulated emission cross-section of Nd(3+) were evaluated. Particularly, the effect of Nd(3+) doping level on them was discussed. With the increase of Nd(3+) concentration in the glass ceramic, the experimental luminescence lifetime, radiative quantum efficiency and stimulated emission cross-section vary from 353.4 micros, 78.3% and 1.86 x 10(-20)cm(2) to 214.7 micros, 39.9% and 1.52 x 10(-20)cm(2), respectively. The comparative study of Nd(3+) spectroscopic parameters in different hosts suggests that the investigated glass ceramic system is potentially applicable as laser materials for 1.06 microm emission.