Thermoluminescent and optical absorption properties of neodymium doped yttrium aluminoborate and yttrium calcium borate glasses

Neodymium doped yttrium aluminoborate and yttrium calcium borate glasses were prepared by the conventional melting-quenching technique with neodymium concentration varying from 0.10 to 1.0 mol%. The obtained glasses present a wide transparency in the UV-visible region (till 240 nm). The thermoluminescent (TL) emission of beta-irradiated samples was measured, showing a broad peak at similar to 240 degrees C with intensities related to the Nd(3+) content, for both glasses. Calcium borate glass samples are about one order of magnitude less luminescent than the aluminoborate glasses. Probably the presence of Ca(2+), instead of Al(3+) and Y(3+) in the matrix, inhibits the production of the intrinsic hole centers. connected to boron and oxygen, known in the literature to act as luminescent centers in TL emission of borate glasses. We suggest that Nd(3+) ions act as electron trapping centers in both glass matrices, as they modify the temperature of emission and the light intensity. Also, the Nd:YAIB glass can be used as a dosimeter in various applications, including radiotherapy. but the sensitivity of this material to neutron should be checked. (C) 2008 Elsevier B.V. All rights reserved.

Structural and spectroscopic characterization of poly(styrene sulfonate) films doped with neodymium ions

This work reports the structural and spectroscopy characterization of poly(styrene sulfonate) (PSS) films doped with neodymium (Nd) ions. Nd-PSS films were processed using the acid of poly(styrene sulfonate) - H-PSS and neodymium nitrate - Nd(NO(3))(3); the maximum incorporation of Nd ions in the polymeric matrix was equal 19.3%. The absorption in the UV-Vis-NIR spectral region presents typical electronic transitions of Nd 3, ions, with well resolved peaks. The infrared spectra present the transition bands of PSS with characteristic line shape broadening, and the presence of vibrational modes of N-O groups in the range of 1400-720 cm(-1), prove the permanence of Nd(NO(3))(x), with x = 1, 2 and/or 3. in the H-PSS matrix. UV-Vis site selective photoluminescence data indicate that the incorporation of Nd 31 introduces a blue shift in PSS emission (325-800 nm), decreasing the interaction between adjacent PSS lateral groups (aromatic rings). Nd(3+) reabsorption and energy transfer effects between the PSS matrix and Nd(3+) were also observed. The IR emission of Nd-PSS films at 1076 rim ((4)F(3/2) -> (4)I(11/2)) present constant efficiency, independent on Nd(3+) concentration. The Judd-Ofelt theory was employed to analyze radiative properties. The excitation spectra prove the energy transfer between the polymeric matrix and Nd(3+). Complex impedance data was used to probe relaxation processes during the charge transport within the polymeric matrix. (C) 2008 Elsevier B.V. All rights reserved.

Surface Activity of the Triflate Ion at the Air/Water Interface and Properties of N,N,N-Trimethyl-N-Dodecylammonium Triflate Aqueous Solutions

The surface activity of salts added to water is Air orders of magnitude lower than that of surfactants. Sodium trifluoromethanesulfonate (NaTf) produced a change in surface tension. with concentration, Delta gamma/Delta c, of -13.2 mN.L/m.mol. This value is ca. 4-fold larger than those of simple salts and that of methanesulfonate. This unexpected surface effect suggested that positively charged micelles containing Tf could exhibit interesting properties. Dodecyltrimethylammonium triflate (DTATf) had a higher Kraft temperature (37 degrees C) and a lower cmc (5 x 10(-3)M) and degree of dissociation (0.11) than the chloride and bromide salts of DTA. Above the Kraft temperature, at a characteristic temperature t(1), the addition of NaTf above 0.05 M. to a DTATf solution induced phase separation. By increasing the temperature of the two-phase system to above t(1), a homogeneous, transparent solution was obtained at a characteristic temperature t(2). These results, together with well-known triflate properties, led us to suggest that the Tf ion pairs With DTA and that the -CF(3) group may be dehydrated in the interfacial region, resulting in new and interesting self-aggregated structures.

Influence of neodymium ions on photocatalytic activity of TiO(2) synthesized by sol-gel and precipitation methods

Titanium dioxide with and without the addition of neodymium ions was prepared using sol-gel and precipitation methods. The resulting catalysts were characterized by thermal analysis, X-ray diffraction and BET specific surface area. Neodymium addition exerted a remarkable influence on the phase transition temperature and the surface properties of the TiO(2) matrix. TiO(2) samples synthesized by precipitation exhibit an exothermic event related from the amorphous to anatase phase transition at 510 degrees C, whereas in Nd-doped TiO(2) this transition occurred at 527 degrees C. A similar effect was observed in samples obtained using sol-gel method. The photocatalytic reactivity of the catalysts was evaluated by photodegradation of Remazol Black B (RB) under ultraviolet irradiation. Nd-doped TiO(2) showed enhanced photodegradation ability compared to undoped TiO(2) samples, independent of the method of synthesis. In samples obtained by sol-gel, RB decoloration was enhanced by 16% for TiO(2) doped with 0.5% neodymium ions. (C) 2010 Elsevier B.V. All rights reserved.

Triflate ion association in plasticized polymer electrolytes

Ion association in plasticised solid polymer electrolytes (SPEs) has been monitored using FT-IR spectroscopy. The SPEs were prepared from a random co-polymer of ethylene oxide (EO) and propylene oxide (PO) and the salt lithium trifluoromethane sulfonate (lithium triflate, LiTf). Tetraethylene glycol dimethylether (tetraglyme, ε˜5) and N,N'-dimethyl formamide (DMF, ε = 36.7) were chosen as model plasticisers. Decreased ion association resulted from plasticization with DMF, indicating that the addition of a higher dielectric constant solvent increases the fraction of dissociated ions in the SPE. The incorporation of tetraglyme into these SPEs results in increased ion association, despite the similar dielectric constants of the plasticiser and polymer host. The effects of salt concentration (0.05–1.25 mol dm^{− 3} solvent) upon ion association in SPEs was also investigated. There appears to be a minimum in the number of “free” ions at a LiTf concentration of 0.2 mol dm^{− 3} solvent followed by a maximum at approximately 0.4 mol dm^{− 3} solvent, consistent with the molar conductivity behaviour previously observed in these electrolytes.

Synthesis and structural diversity of rare earth anthranilate complexes

Four structural classes have been established for rare earth anthranilates, which have been prepared from the lanthanoid chloride or triflate and anthranilic acid (anthH) followed by pH adjustment to 4. [La(anth)3]n is a polymeric complex with nine coordinate lanthanum and bridging tridentate (O,O,O′) anthranilate ligands, whereas [Nd(anth)3(H2O)3] · 3H2O is monomeric with nine coordinate neodymium and solely chelating (O,O) anthranilate groups. Both chelating (O,O) and bridging bidentate (O,O′) ligands are observed in dimeric [Er2(anth)6(H2O)4] · 2H2O, in which erbium is eight coordinate and the water ligands are in a trans arrangement. A polymer is observed for [Yb(anth)3(H2O)]n with solely bridging bidentate (O,O′) ligands and seven coordination for ytterbium. The NH2 groups of the anthranilate ligands are not coordinated to the metal but is unusually involved in hydrogen-bond networks with water molecules for Ln = Er, Yb.

Ionic conductivity in poly(diethylene glycol-carbonate)/sodium triflate complexes

New polymer electrolytes were synthesized and characterized based on a new polymer host. The motivation was to produce a host polymer with a high dielectric constant which should reduce ion clustering with an attendant increased conductivity. The new polymer host, poly(diethylene glycol carbonate) and its sodium triflate complexes were characterized by thermal analysis and AC impedance measurements. The polycarbonate backbone appears less flexible than the polyether hosts as evidenced by the higher glass transition temperatures. The conductivity for the sodium triflate complexes was measured as ~ 10⁻⁵ S cm⁻¹ at 55 °C and the dielectric constant of the host polymer was found to be 3.6 at 3 GHz. The low conductivity is attributed to rigidity of the polycarbonate.

An organic ionic plastic crystal electrolyte based on the triflate anion exhibiting high proton transport

A novel organic ionic plastic crystal (OIPC) electrolyte based on a quaternary ammonium cation and the triflate anion has been synthesized, which shows fast proton transport and high thermal stability in the solid state when doped with triflic acid.

New series of intramolecularly coordinated diaryltellurium compounds. Rational synthesis of the diarylhydroxytelluronium triflate [(8-Me 2NC 10H 6) 2Te(OH)](O 3SCF 3)

The reaction of 8-dimethylaminonaphthyllithium etherate with the tellurium(II) bis(dithiocarbamate) Te(S₂CNEt₂)₂ provided the diaryltelluride (8-Me₂NC₁₀H₆)₂Te (1). The oxidation of 1 with an excess of H₂O₂ did not afford the expected diaryltellurium(IV) oxide (8-Me₂NC₁₀H₆)₂TeO (2), but the diaryltellurium(VI) dioxide (8-Me₂NC₁₀H₆)₂TeO₂ (3). The preparation of 2 was achieved by the comproportionation reaction of 1 and 3. The protonation of 2 using triflic acid gave rise to the formation of diarylhydroxytelluronium triflate [(8-Me₂NC₁₀H₆)₂Te(OH)](O₃SCF₃) (4), which features the protonated diaryltellurium oxide [(8-Me₂NC₁₀H₆)₂Te(OH)]+ (4a). Compounds 1, 3·H₂O·H₂O₂, 3·2H₂O, and 4 were characterized by X-ray crystallography. The experimentally obtained molecular structures were compared to those calculated for 1–3, 4a, and (8-Me₂NC₁₀H₆)₂Te(OH)₂ (5) as well as the related diphenyltellurium compounds Ph₂Te (6), Ph₂TeO (7), Ph₂TeO₂ (8), [Ph₂Te(OH)]+ (9a), and Ph₂Te(OH)₂ (10) at the DFT/B3PW91 level of theory.

Probing ion exchange in the triflic acid-guanidinium triflate system: a solid-state nuclear magnetic resonance study

Knowledge of ion exchange and transport behavior in electrolyte materials is crucial for designing and developing novel electrolytes for electrochemical device applications such as fuel cells or batteries. In the present study, we show that, upon the addition of triflic acid (HTf) to the guanidinium triflate (GTf) solid-state matrix, several orders of magnitude enhancement in the proton conductivity can be achieved. The static 1H and 19F solid-state NMR results show that the addition of HTf has no apparent effect on local molecular mobility of the GTf matrix at room temperature. At higher temperatures, however, the HTf exhibits fast ion exchange with the GTf matrix. The exchange rate, as quantified by our continuum T2 fitting analysis, increases with increasing temperature. The activation energy for the chemical exchange process was estimated to be 58.4 kJ/mol. It is anticipated that the solid-state NMR techniques used in this study may be also applied to other organic solid-state electrolyte systems to investigate their ion-exchange processes.

Biosorption and desorption of lanthanum(III) and neodymium(III) in fixed-bed columns with Sargassum sp.: Perspectives for separation of rare earth metals

Rare earth (RE) metals are essentials for the manufacturing of high-technology products. The separation of RE is complex and expensive; biosorption is an alternative to conventional processes. This work focuses on the biosorption of monocomponent and bicomponent solutions of lanthanum(III) and neodymium(III) in fixed-bed columns using Sargassum sp. biomass. The desorption of metals with HCl 0.10 mol L-1 from loaded biomass is also carried out with the objective of increasing the efficiency of metal separation. Simple models have been successfully used to model breakthrough curves (i.e., Thomas, Bohart-Adams, and Yoon-Nelson equations) for the biosorption of monocomponent solutions. From biosorption and desorption experiments in both monocomponent and bicomponent solutions, a slight selectivity of the biomass for Nd(III) over La(III) is observed. The experiments did not find an effective separation of the RE studied, but their results indicate a possible partition between the metals, which is the fundamental condition for separation perspectives. (C) 2012 American Institute of Chemical Engineers Biotechnol. Prog., 2012