Temporal and spatial evolution of laser ablated plasma from YBa2Cu3O7

YBa2Cu307 target was laser ablated, and the time-of-flight (TOF) distributions of Y, Y+., and YO in the resultant plasma were investigated as functions of distance from the target and laser energy density using emission spectroscopy. Up to a short distance from the target (-1.5 cm), TOF distributions show twin peaks for Y and YO, while only single-peak distribution is observed for Y+. At greater distances (>1.5 cm) all of them exhibit single-peak distribution. The twin peaks are assigned to species corresponding to those generated directly/m the vicinity of target surface and to those generated from collisional/recombination process.

Solvent extraction of scandium(III), yttrium(III), lanthanides(III), and divalent metal ions with sec-nonylphenoxy acetic acid

Such physicochemical properties of sec-nonylphenoxy acetic acid (CA-100) as the solubility in water, acid dissociation constant in water, dimerization constant in heptane, and distribution constant in organic solvent-water were measured by two-phase titration. The extraction behaviors of scandium (III), yttrium (III), lanthanides (III), and divalent metal ions from hydrochloric acid solutions with CA-100 in heptane have been investigated, and the possibilities of separating scandium (yttrium) from lanthanides and divalent metal ions have been carefully discussed. The stoichiometries of the extracted metal complexes were investigated by the slope-analysis technique. The effect of the nature of diluent on the extraction of yttrium (III) with CA100 has been studied and correlated with the dielectric constant.

High temperature stability of oxysulfides containing Ce3+ and Y3+ ions

Standard Gibbs energies of formation of oxysulfides of cerium and yttrium from their respective oxedes were determined using solid oxide galvanic cells incorporating calcia-stabilized zirconia as the electrolyte in the temperature range 870–1120 K. The sulfur potential over the electrode containing the oxide and oxysulfide was fixed by a buffer mixture of Ag + Ag2S. A small amount of CaH2 was added to the buffer to generate an equilibrium ratio of H2S and H2 species in a closed system containing the buffer and the electrode. The sulfur potential is transmitted to the electrode via the gas phase. The results can be summarized by the equations 2left angle bracketCeO2right-pointing angle bracket+1/2(S2)→left angle bracketCe2O2Sright-pointing angle bracket+(O2) ΔG°=430600−109·7T(±400)J mol−1 left angle bracketY2O3right-pointing angle bracket+1/2(S2)→left angle bracketY2O2Sright-pointing angle bracket+1/2(O2) ΔG°=114780−1·45T(±200)J mol−1 The values are compared with data reported in the literature. The stability field diagram for the Ce---O---S system has been developed using the results of this study for Ce2O2S and data for other phases from the literature.

Thermoluminescence, photoluminescence and EPR studies on Mn2+ activated yttrium aluminate (YAlO3) perovskite

Thermoluminescence (TL) measurements were carried out on undoped and Mn2+ doped (0.1 mol%) yttrium aluminate (YAlO3) nanopowders using gamma irradiation in the dose range 1-5 kGy. These phosphors have been prepared at furnace temperatures as low as 400 degrees C by using the combustion route. Powder X-ray diffraction confirms the orthorhombic phase. SEM micrographs show that the powders are spherical in shape, porous with fused state and the size of the particles appeared to be in the range 50-150 nm. Electron Paramagnetic Resonance (EPR) studies reveal that Mn ions occupy the yttrium site and the valency of manganese remains as Mn2+. The photoluminescence spectrum shows a typical orange-to-red emission at 595 nm and suggests that Mn2+ ions are in strong crystalline environment. It is observed that TL intensity increases with gamma dose in both undoped and Mn doped samples. Four shouldered TL peaks at 126, 240, 288 and 350 degrees C along with relatively resolved glow peak at 180 degrees C were observed in undoped sample. However, the Mn doped samples show a shouldered peak at 115 degrees C along with two well defined peaks at similar to 215 and 275 degrees C. It is observed that TL glow peaks were shifted in Mn doped samples. The kinetic parameters namely activation energy (E), order of kinetics (b), frequency factor (s) of undoped, and Mn doped samples were determined at different gamma doses using the Chens glow peak shape method and the results are discussed in detail. (C) 2012 Elsevier B.V. All rights reserved.

Upconversion luminescence in Yb3+-doped yttrium aluminum garnets

In this paper, we present results on upconversion luminescence performed on Yb3+-doped yttrium aluminum garnets under 940 nm excitation. The upconversion luminescence was ascribed to Yb3+ cooperative luminescence and the presence of rare earth impurity ions. The cooperative luminescence spectra as a function of Yb concentration were measured and the emission intensity variation with Yb concentration was discussed. Yb3+ energy migration quenched the cooperative luminescence of Yb:YAG crystals with doping level over 15 at%. (c) 2004 Elsevier B.V. All rights reserved.

Cooperative and charge transfer luminescence in Yb3+ -doped yttrium aluminum perovskite (YAlO3)

YAlO3 (YAP) crystals with different Yb3+ concentration have been grown by Czochralski method and cooperative fluorescence of Yb3+ ions in YAP crystal was studied under 940-nm infrared (IR) LD excitation at room temperature. The Yb concentration dependence of absorption intensity of IR and charge transfer bands exhibit different features. The green emission band in the region of 480-520nm was assigned to the cooperative deexcitation of two Yb3+ ions. The remaining upconverted emission bands containing various sharp peaks associated with impurity ions were observed and discussed. Charge transfer luminescence of heavily doped 20at% Yb:YAP is strongly temperature dependent and no concentration quenching of the charge transfer luminescence was found through the investigation of different Yb levels samples. (c) 2006 Elsevier B.V. All rights reserved.

An effective method for enhancing metal-ions' selectivity of ionic liquid-based extraction system: Adding water-soluble complexing agent

Selective extraction-separation of yttrium(Ill) from heavy lanthanides into 1-octyl-3-methylimidazolium hexafluorophosphate ([C(8)mim][PF6]) containing Cyanex 923 was achieved by adding a water-soluble complexing agent (EDTA) to aqueous phase. The simple and environmentally benign complexing method was proved to be an effective strategy for enhancing the selectivity of [C(n)mim] [PF6]/[Tf2N]-based extraction system without increasing the loss of [C(n)mim](+). (c) 2007 Elsevier B.V. All rights reserved.

The solid-liquid extraction of yttrium from rare earths by solvent (ionic liquid) impreganated resin coupled with complexing method

A kind of solvent (ionic liquid) impreganated resin (IL-SIR) was developed herein for ameliorating imidazolium-type IL-based liquid-liquid extraction of metal ions. In this study, [C(8)mim][PF6] containing Cyanex923 was immobilized on XAD-7 resin for solid-liquid extraction of rare earth (RE). The solid-liquid extraction contributed to ameliorating mass transfer efficiency, i.e. shortening equilibrium time from 40 min to 20 min, increasing extraction efficiency from 29% to 80%. In additional, the novel IL-SIR could separate Y(III) from Sc(III), Ho(III), Er(III), Yb(III) effectively by adding water-soluble complexing agent.

The preparation of sol-gel materials doped with ionic liquids and trialkyl phosphine oxides for Yttrium(III) uptake

A new material (IL923SGs) composed of ionic liquids and trialkyl phosphine oxides (Cyanex 923) for Y(III) uptake was prepared via a sol-gel method. The hydrophobic ionic liquid 1-octyl-3-methylimidazolium hexafluorophosphate (C(8)mim(+)PF(6)-) was used as solvent medium and pore templating material. The extraction of Y(III) by IL923SGs was mainly due to the complexation of metal ions with Cyanex 923 doped in the solid silica. Ionic liquid was stably doped into the silica gel matrix providing a diffusion medium for Cyanex 923, and this will result in higher removal efficiencies and excellent stability for metal ions separation. IL923SGs were also easily regenerated and reused in the subsequent removal of Y(III) in four cycles.

Separation of yttrium from heavy lanthanide by CA-100 using the complexing agent

The selective extraction of yttrium front heavy lanthanide by liquid-liquid extraction using CA-100 in the presence of the complexing agent, such as EDTA, DTPA, and HEDTA was investigated. The extraction of heavy lanthanide in the present of the complexing agent was Suppressed when compared to that of Y because of the masking effect, but the selective extraction of Y was enhanced. All complexing agents formed 1: 1 complex with rare earth elements (RE), and only free rare earth ions could take part in the extraction. The condition for separation was obtained by exploring the effects of the complexing agent concentration, the extractant concentration, pH and the equilibration time on the extraction of the heavy rare earth elements.

Selective separation of yttrium by CA-100 in the presence of a complexing agent

The selective separation of Y from yttrium solution containing small heavy rare earth (HRE) impurities (Ho, Er, Tm, Yb, Lu) by liquid-liquid extraction using CA-100 in the presence of a water-soluble complexing agent of ethylenediaminetetraacetic acid (EDTA) was experimentally studied at 298K. Experiments were carried Out in two feeds, Feed-I: [RE](f) = 4.94 x 10(-3) M, Y = 98.5%, HRE (Ho, Er, Tm, Yb, Lu) = 1.5%; Feed-II: [RE](f) = 4.94 x 10(-3) M, Y = 99.9%, HRE (Ho, Er, Tm, Yb, Lu) = 0.1%, as a function of equilibrium pH (pH(eq)), the concentration ratio of [EDTA]:[HRE impurities]. It was shown that the extraction of HRE in the presence of EDTA was suppressed when compared to that of Y because of the masking effect, while the selective extraction of Y was enhanced and the separation factors increased to maximum at appropriate condition for Feed-I: Y/Ho = 1.53, Y/Er = 3.09, Y/Tm = 5.61, Y/Yb = 12.04, Y/Lu = 27.51 at pH 4.37 and [EDTA]:[HRE impurities] = 4: 1, for Feed-II: Y/Ho = 1.32, Y/Er = 1.91, Y/Tm = 2.00, Y/Yb = 3.05, Y/Lu = 3.33 at pH 4.42 and [EDTA]: [HRE impurities] = 8:1. The separation and purification of Y by this method was discussed.

Studies on the roles of different components in Cyanex 302 for rare earth ions extraction and separation

In this paper, the extractabilities of Cyanex 302 and purified Cyanex 302 (hereafter HBTMPTP or HA) in heptane have been compared by extracting the scandium, yttrium, lanthanum, and gadolinium from hydrochloric acid solutions. The roles of the different components in Cyanex 302 on lanthanum extraction have been analyzed. The result demonstrates that the Cyanex 302 has a higher extractability than HBTMPTP, which perhaps originates from the interaction among the components in Cyanex 302. Especially for R3PO, obviously synergistic effect can be observed in the lower pH range and extraction mechanism of lanthanum using the mixture of HBTMPTP and TOPO has been deduced to be:where (HA)(2) and B denote the dimeric form of HBTMPTP and TOPO, respectively. At the same time, the separation abilities of Cyanex 302 and HBTMPTP on the rare earth elements have been compared. Also, the effect of temperature on the extraction with Cyaenx 302, HBTMPTP and the mixture of HBTMPTP and TOPO has also been discussed with thermodynamic functions Delta H, Delta S, and Delta G calculated.

SPECTRAL CHARACTERISTICS OF ER3+-ACTIVATED AND CE3+-SENSITIZED YTTRIUM-ALUMINUM-GARNET LASER CRYSTALS

We report in this paper the spectral characteristics of Er3+ (2 at.%)-activated and Ce3+ (0.3 at.%)-sensitized yttrium aluminium garnet (YAG:Er,Ce) laser crystals grown by the Czochralski technique. The absorption and emission spectra were measured at room temperature. By using absorption spectra and Judd-Ofelt theory the experimental oscillator strengths of the Er3+ transitions in the YAG:Er,Ce crystals were calculated. The energy transfer between the Er3+ and Ce3+ ions is also discussed.

Dielectronic recombination in He-like, Li-like, and Be-like highly charged ions in the KLL and KLM manifolds

This paper reports a systematic study of the dependence on atomic number of the dielectronic recombination resonance strengths for He-like, Li-like and Be-like ions. Recent measurements of dielectronic recombination resonance strengths for the KLL and KLM manifolds for iron, yttrium, iodine, holmium, and bismuth are also described. The resonance strengths were normalized to calculated electron impact ionization cross sections. The measured resonance strengths generally agree well with theoretical calculations using the distorted wave approximation. However, KLM resonance strength measurements on high atomic number open-shell ions gave higher values than those suggested by calculations. Using recently measured data, along with existing results, scaling laws have been generated as a function of atomic number for He-like, Li-like, and Be-like ions in the KLL and KLM manifolds.