Detection of up-conversion in nano-structure BaTiO<Subscript>3</Subscript> co-doped with Er<Superscript>3+</Superscript> and Yb<Superscript>3+</Superscript> ions

Nano-structure pure barium titanate BaTiO₃ (BT) and (BT) co-doped with constant concentration of Er³⁺ ions and different concentrations of Yb³⁺ ions were prepared using sol–gel method. XRD results confirmed that the pure sample was found to crystallize in tetragonal phase by sintering at 750 °C for 1 h. All major peaks corresponding to perovskite BT phase appeared. Efficient infrared-to-visible up-conversion is reported in the doped samples. The conversion process and results in the generation of visible emissions are discussed. Up-conversion efficiency for red emission predominates in doped samples. Results illustrate the large potential of this class of materials for photonic applications in optoelectronics devices.     

Water-soluble polymers as chelating agents for the deposition of Er<Superscript>3+</Superscript>/Yb<Superscript>3+</Superscript>:LiNbO<Subscript>3</Subscript> waveguiding films

Compared to other oxide materials, the sol-gel deposition of an optically transparent LiNbO₃ waveguiding film of sufficient thickness (approx. 1?μm) is complicated by the presence of a highly hydrolyzing Nb(V) in the starting solution. Thicker films require more concentrated solutions that are not easily achieved for such ions. This problem may be solved using strong chelating agents such as water-soluble polymers. To prepare a stable Er(III)/Yb(III)/Li(I)/Nb(V)/2-methoxyethanol solution with high metal concentration, we tested three such polymers: polyethylene glycol (PEG), polyacrylic acid (PAA) and polyvinyl alcohol (PVA), and compared them with already used polyvinylpyrrolidone (PVP). The solutions were spin-coated on crystalline sapphire substrates under a multi-step heating-deposition regime. Apart from Er³⁺/Yb³⁺ photoluminescence properties, we evaluated the influence of the film microstructure (SEM, AFM) on optical transparency and waveguiding ability in the UV/Vis/NIR region (transmission and m-line spectroscopy). Among the newly tested polymers, only PEG was able to prevent Nb(V) hydrolysis up to a maximum metal concentration of 0.6?mol/L. For PEG and PVP, the crystallization temperature of the deposited films (between 700?°C and 1000?°C) was compared. After further optimization of the heating-deposition process, we were able to prepare a transparent Er³⁺/Yb³⁺:LiNbO₃ film thick enough to guide an optical signal in the NIR region. Thus, the use of PEG results is one of the very few non-hydrolytic sol-gel methods suitable for the preparation of not only luminescent, but also waveguiding Er³⁺/Yb³⁺:LiNbO₃ structures.

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Near-infrared quantum cutting in Tb<Superscript>3+</Superscript> and Yb<Superscript>3+</Superscript>-doped Y<Subscript>2</Subscript>O<Subscript>3</Subscript> nanophosphors

Properties of the quantum-cutting phosphors are dependent on various factors such as dopant concentration, crystallinity, homogeneity, particle size and surface morphology. Effective control of the above parameters can enhance the quantum-cutting ability of the phosphor material. Nano-sized particles of Y₂O₃:Tb³⁺,Yb³⁺ were prepared with a solution-based co-precipitation method and subsequent calcination. Effective control of the reaction parameters and doping concentration helped to produce uniform nanostructures with high quantum-cutting efficiency up to 181.1 %. The energy transfer mechanism between Tb³⁺ and Yb³⁺ was studied by considering their spectroscopic properties and time-resolved spectroscopy. The high efficiency and small particle size of the quantum-cutting phosphor Y₂O₃:Tb³⁺,Yb³⁺ make it a suitable candidate for its application in solar cells.     

Opposite effect of Li<Superscript>+</Superscript> codoping on the upconversion emissions of Er<Superscript>3+</Superscript>-doped TiO<Subscript>2</Subscript> powders

The Er³⁺-Li⁺ codoped TiO₂ powders have been prepared by the non-aqueous sol–gel method. The green and red upconversion emissions centered at about 526, 550 and 663 nm were observed by the ²H_11/2, ⁴S_3/2 → ⁴I_15/2 and ⁴F_9/2 → ⁴I_15/2 transitions of Er³⁺, respectively. Li⁺ codoping has opposite effect on the upconversion emissions intensities for Er³⁺-doped TiO₂ at sintering temperatures of 1,073 and 1,273 K. At 1,073 K, the Er³⁺-doped TiO₂ phase transition from anatase to rutile was accelerated with increasing Li⁺ codoping concentration, leading to the increase of crystal field symmetry of Er³⁺, thus the upconversion emissions intensities decreased. At 1,273 K, Li⁺ codoping had no effect on the phase structure of Er³⁺-doped TiO₂ and only increased the Er–O bond length, it indicated that the upconversion emissions intensities greatly enhanced because of the decrease of crystal field symmetry of Er³⁺.     

Two color up-conversion emissions of Er<Superscript>3+</Superscript>-doped Al<Subscript>2</Subscript>O<Subscript>3</Subscript> nanopowders prepared by non-aqueous sol-gel method

Er³⁺-doped Al₂O₃ nanopowders have been prepared by the non-aqueous sol-gel method using the aluminum isopropoxide as precursor, acetylacetone as a chelating agent, nitric acid as a catalyzer, and hydrated erbium nitrate as a dopant under isopropanol environment. The different phase structure, including three crystalline types of (Al, Er)₂O₃ phases, α, γ, θ, and an Er–Al–O stoichiometric compound phase, Al₁₀Er₆O₂₄, was observed for the 0.01–0.5 mol% Er³⁺-doped Al₂O₃ nanopowders at the sintering temperature of 1,000 °C. The green and red up-conversion emissions centered at about 523, 545 and 660 nm, corresponding respectively to the ²H_11/2, ⁴S_3/2→⁴I_15/2 and ⁴F_9/2→⁴I_15/2 transitions of Er³⁺, were detected by a 978 nm semiconductor laser diodes excitation. With increasing Er³⁺ doping concentration from 0.01 to 0.1 mol%, the intensity of the green and red emissions increased with a decrease of the intensity ratio of the green to red emission. When the Er³⁺ doping concentration rose to 5 mol%, the intensity of the green and red emissions decreased with an increase of their intensity ratio. The maximum intensity of both the green and red emissions with the minimum of intensity ratio was obtained, respectively, for the 0.1 mol% Er³⁺-doped Al₂O₃ nanopowders composed of a single α-(Al,Er)₂O₃ phase. The intensity ratio of the green emission at 523 and 545 nm increased monotonously for all Er³⁺ doping concentrations. The two-photon absorption up-conversion process was involved in the green and red up-conversion emissions of the Er³⁺-doped Al₂O₃ nanopowders.     

Thermodynamics of reactions of complex formation for Ce<Superscript>3+</Superscript> and Er<Superscript>3+</Superscript> ions with glycine in an aqueous solution

Enthalpies of complex formation for glycine (HL^±) with Ce³⁺ and Er³⁺ ions at 298.15 K and the value of the ionic strength of 0.5 (KNO₃) are determined by calorimetric means using two independent procedures. Thermodynamic characteristics of the reactions of formation for complexes of glycine with Ce³⁺ and Er³⁺ ions at various [metal]: [ligand] molar ratios are calculated.     

Yb<Superscript>3+</Superscript> doped dyphillosilicates prepared by thermally induced phase transformation of zeolites

Yb³⁺-doped Ba and Sr diphyllosilicates (hexacelsians) have been synthesized using the Na form of LTA zeolite by ion-exchange procedure and thermal treatment. The crystal structures of both doped samples are refined and described in this article. The results of Rietveld refinements clearly indicate that Yb³⁺ ions are incorporated into the hexacelsians structure. AFM photomicrographs show round-shaped particles with the size of few microns. The magnetization measurements were done within the 2–300 K temperature range, revealing an enhancement of magnetization with temperature that is not in accordance with simple paramagnetic behavior. The text was submitted by the authors in English.     

Selective extraction of Fe<Superscript>3+</Superscript> ions from Fe<Superscript>3+</Superscript>-Zn<Superscript>2+</Superscript> mixture with phosphate sorbents

The absorption of Fe³⁺ ions from Fe³⁺-Zn²⁺ mixture with zinc and calcium phosphates was studied.     

Intercalation of cytosine into Eu<Superscript>3+</Superscript>-doped hydrocalumite and their fluorescent responses

Intercalation of cytosine into Eu³⁺-doped hydrocalumites and the fluorescence of the Eu³⁺-doped hydrocalumite response to cytosine has been investigated. XRD patterns showed that the basal spacing of Eu-doped hydrocalumite obviously increased after it exposed to various content of cytosine, revealing the intercalation of cytosine into Eu³⁺-doped hydrocalumite. TG-DSC curves and IR spectra of the intercalated samples are different from that of the Eu-doped hydrocalumite and cytosine, indicating the interaction between the Eu³⁺-doped hydrocalumite and cytosine. Fluorescent spectra suggested that the fluorescent changes of Eu³⁺-doped hydrocalumite depended on the concentration of cytosine solution. This fluorescent change would be potential application in biological probe in view of the biocompatibility of Ca²⁺ ions and the fluorescence of Eu³⁺ ions. Moreover, the Eu³⁺-doped hydrocalumite would be a healthy and cheap fluorescent material applied in biology or healing drugs fields.     

Eu<Superscript>3+</Superscript>-doped LaPO<Subscript>4</Subscript> and LaAlO<Subscript>3</Subscript> nanosystems and their luminescence properties

Eu³⁺ ion-doped LaPO₄ nanowires or nanorods have been successfully synthesized by a simple hydrothermal method. The influence of varying the hydrothermal and subsequent sintering conditions on the morphology and structure of the LaPO₄ host has been investigated by scanning electron microscopy (SEM) and X-ray diffraction (XRD). For comparison, the Eu³⁺ ions were also doped into monoclinic monazite LaPO₄ nanoparticles and perovskite LaAlO₃ nanoparticles. The relative intensities of the emission lines of the LaPO₄:Eu³⁺ nanosystems were essentially independent of their shape. The optimal doping concentrations in the monoclinic LaPO₄ and perovskite LaAlO₃ nanosystems were determined to be about 5.0 and 3.5 mol%, respectively. Under appropriate UV-radiation, the red light emitted from LaAlO₃:Eu³⁺ (3.5 mol%) was brighter than that from LaPO₄:Eu³⁺ (5.0 mol%) nanomaterial, resulting from differences in their spin-orbit couplings and covalence, which indicates that the nanoscale LaAlO₃ is a promising host material for rare earth ions. Electronic Supplementary Material  Supplementary material is available for this article at and is accessible for authorized users. Supported by the National Natural Science Foundation of China (Grant Nos. 20873039 & 90606001), Hunan Provincial Natural Science Foundation (No. 07jj4002), and the Students Innovation Training Fund of Hunan University     

Hydrolytic Behavior of La<Superscript>3+</Superscript> and Sm<Superscript>3+</Superscript> at Various Temperatures

The hydrolytic species of lanthanide ions, La³⁺ and Sm³⁺, in water at I = 0.1 mol·dm^?3 KCl ionic strength and temperatures of 298.15, 310.15 and 318.15 K were investigated by potentiometry. The hydrolytic species were modeled by the HySS simulation program. From the results, the hydrolytic species of each metal ion at different temperatures were calculated using the program HYPERQUAD2013. The hydrolysis constants (log₁₀ β) of [La(OH)]²⁺ and La(OH)₃ were calculated as ?8.52 ± 0.46, ?26.84 ± 0.48, and log₁₀ β values of [Sm(OH)]²⁺, [Sm(OH)₂]⁺, Sm(OH)₃ were calculated as ?7.11 ± 0.21, ?15.84 ± 0.25 and ?23.44 ± 0.52 in aqueous media at 298.15 K, respectively. The dependence of the hydrolysis constants on the temperature allowed us to calculate the enthalpy, entropy, and Gibbs energy of hydrolysis values of each species.     

EPR and optical study of coupled Yb<Superscript>3+</Superscript> ion pairs in weakly doped LiNbO<Subscript>3</Subscript>:Yb single crystal

The results of electron paramagnetic resonance and optical spectroscopy studies of Yb³⁺ ions in LiNbO₃:1% Yb host crystal are reported. Also some results of Raman spectra measurements are presented. The observed features are assigned to single Yb³⁺ ions and pairs of dissimilar ions (with different g value) of the type of ^evenYb³⁺-^evenYb³⁺. The values of the components of the g-tensor for both ions and interaction exchange tensors are estimated. The value of J = ?0.0283 cm^?1 shows that the exchange interactions are of antiferromagnetic nature. The most probably the ^evenYb³⁺-^evenYb³⁺ pairs substitute for neighborhood Li⁺-Nb⁵⁺ positions what induces gain of distance between ions of about 1 Å. There are no observed dissimilar ion pairs of the type ^oddYb³⁺-^oddYb³⁺.     

Effect of Ca<Superscript>2+</Superscript>, Mg<Superscript>2+</Superscript>, Fe<Superscript>3+</Superscript>, and Al<Superscript>3+</Superscript> Ions on the Deposition of Electrolytic Manganese Dioxide from Chloride Solutions

The effect of Ca²⁺, Mg²⁺, Fe³⁺, and Al³⁺ ions on the deposition of electrolytic manganese dioxide from chloride solutions was studied.__________Translated from Zhurnal Prikladnoi Khimii, Vol. 78, No. 5, 2005, pp. 751–754.Original Russian Text Copyright © 2005 by Kolosnitsyn, Minnikhanova, Karaseva, Dmitriev, Muratov.     

Extraction of metal ions (Fe<Superscript>3+</Superscript>, Co<Superscript>2+</Superscript>, Ni<Superscript>2+</Superscript>, Cu<Superscript>2+</Superscript> and Zn<Superscript>2+</Superscript>) using immobilized-polysiloxane iminobis(n-2-aminophenylacetamide) ligand system

A new insoluble solid functionalized ligand system bearing chelating ligand group of the general formula P-(CH₂)₃-N[CH₂CONH(C₆H₄)NH₂]₂, where P represents [Si–O] _n polysiloxane network, was prepared by the reaction of the immobilized diethyliminodiacetate polysiloxane ligand system, P-(CH₂)₃N(CH₂CO₂Et)₂ with 1,2-diaminobenzene in toluene. ¹³C CP-MAS NMR, XPS and FTIR results showed that most ethylacetate groups (–COOEt) were converted into the amide groups (–N–C=O). The new functionalized ligand system exhibits high capacity for extraction and removal of the metal ions (Fe³⁺, Co²⁺, Ni²⁺, Cu²⁺ and Zn²⁺) with efficiency of 95–97% after recovery from its primary metal complexes. This functionalized ligand system formed 1:1 metal to ligand complexes.     

Thermodynamics of citrate complexation with Mn<Superscript>2+</Superscript>, Co<Superscript>2+</Superscript>, Ni<Superscript>2+</Superscript> and Zn<Superscript>2+</Superscript> ions

Isothermal titration calorimetry has been used to determine the stoichiometry, formation constants and thermodynamic parameters (ΔG ^o, ΔH, ΔS) for the formation of the citrate complexes with the Mn²⁺, Co²⁺, Ni²⁺ and Zn²⁺ ions. The measurements were run in Cacodylate, Pipes and Mes buffer solutions with a pH of 6, at 298.15 K. A constant ionic strength of 100 mM was maintained with NaClO₄. The influence of a metal ion on its interaction energy with the citrate ions and the stability of the resulting complexes have been discussed.     

Synthesis,characterization, and photocatalytic properties of La<Superscript>3+</Superscript>-doped BiPO<Subscript>4</Subscript> photocatalysts

La³⁺-doped BiPO₄ photocatalysts were prepared via a hydrothermal process. Their morphologies, structures, and light absorption properties were evaluated. A small amount of La-doping (optimized at 2 mol %) could significantly improve the activity of BiPO₄ in the degradation of methylene blue under ultraviolet irradiation. After five recycles, the La³⁺-doped BiPO₄ did not exhibit any apparent loss in activity, confirming its stability despite recycling.     

The New Fluorescence Enhancement System Eu<Superscript>3+</Superscript>-ARADE-HMTM-Al<Superscript>3+</Superscript> and its Analytical Application

A new bis-Schiff base ligand, N,N-bis-(4-N-aminothiourea-2-amylidene)-4,4-diaminodiphenyl ether (ARADE), was synthesized. Its complex with Eu³⁺ in DMF emits the intrinsic fluorescence of Eu³⁺. The fluorescence intensity of the Eu³⁺-ARADE system was enhanced about 60-fold by the addition of hexamethylene tetramine (HMTM) and potash alum. This is a new fluorescence enhancement phenomenon. The excitation and emission wavelengths are 375nm and 615nm, respectively. Under optimal conditions, the fluorescence intensities vary linearly with the concentration of Eu³⁺ in the range of 7.8×10^–9–1.75×10^–5mol·L^–1 with a detection limit of 5.2×10^–9mol·L^–1, or with the concentration of Al³⁺ in the range of 3.1×10^–7–9.7×10^–5mol·L^–1 with a detection limit of 2.7×10^–7mol·L^–1. The interferences of some rare earth metals and other inorganic ions were described. This method was applied to the determination of Eu³⁺ in high purity yttrium oxide and the analysis of Al³⁺ in alloy steel standard samples. The mechanism of fluorescence enhancement was also studied.     

Scalar-relativistic 5f-in-core pseudopotentials and core-polarization potentials for trivalent actinides: calibration calculations for Ac<Superscript>3+</Superscript>, Cm<Superscript>3+</Superscript> and Lr<Superscript>3+</Superscript> complexes

The performance of recently proposed 5f-in-core pseudopotentials for the trivalent actinides was investigated in calculations for model complexes An³⁺L ⁿ⁻ for three selected actinides (An³⁺ = Ac³⁺, Cm³⁺, Lr³⁺) and eight simple ligands with atoms from the first three periods of the table of elements (L ⁿ⁻ = F⁻, Cl⁻, OH⁻, SH⁻, CO, NH₂⁻, H₂O, H₂S, NH₃). Results of Hartree-Fock and Coupled Cluster with singles, doubles and perturbative triples calculations using basis sets of quadruple-zeta quality are compared to corresponding reference data obtained with scalar-relativistic energy-adjusted 5f-in-valence small-core pseudopotentials. The inclusion of core-polarization potentials in the 5f-in-core pseudopotential calculations and corrections of the basis set superposition error by the counterpoise correction leads to very good agreement between the 5f-in-valence and 5f-in-core pseudopotential results for bond lengths, bond angles and binding energies. Results from 5f-in-core pseudopotential calculations using different density functionals also show reasonable agreement with the more rigorous Coupled Cluster results. It is argued that the An 5f rather than the An f population is a useful criterion for the applicability of a specific An 5f-in-core pseudopotential.     

Effects of La<Superscript>3+</Superscript> and Eu<Superscript>3+</Superscript> on outward potassium channels in Vicia guard cells

Effects of La³⁺ and Eu³⁺ on outward potassium channels (K_out⁺) in Vicia guard cells have been studied by patch clamping technique. Extracellular La³⁺ inhibited K_out⁺ currents with a half-inhibition concentration (IC₅₀) of 81 μmol·L⁻¹. Interestingly, intracellular La³⁺ activated K_out⁺ currents at a free concentration of 1.13 × 10⁻¹⁴ mol·L⁻¹, and inhibited K_out⁺ currents at a free concentration of 5.86 × 10⁻¹⁴ mol·L⁻¹. Extracellular Eu³⁺ also activated K_out⁺ currents at concentrations of 10 μmol·L⁻¹ and 50 μmol·L⁻¹, and inhibited K_out⁺ currents at concentrations of more than 1 mmol·L⁻¹. The effects of La³⁺ and Eu³⁺ on K_out⁺ currents may contribute to regulation of the plant water status, which may be one of the mechanisms of the biological effect of rare earth elements.