Papers by Keyword: Lanthanide

Abstract: The present work describes the extraction of lanthanide (rare earth elements, REE) from low grade bauxite using acid leaching method. The aim of this study is to obtain the best condition for extraction of lanthanides from low grade bauxite. The effect of different parameters such as temperatures and concentration of oxalic acid in leaching process were investigated. The content of La, Ce and Y elements were determined using ICP-OES. The experimental result shows that the efficiencies of lanthanide leaching are the temperature-dependent. Increasing leaching temperature from 45°C to 85°C did not improve recoveries of lanthanides. The most optimum condition was found at oxalic acid leaching of 1 mol/L, leaching temperature at 40°C, and time for 2 hours. The obtained results show that the lanthanides can be leached using oxalic axid. This finding may lead to more effective and economical method to separate lanthanides from low grade bauxite.

Abstract: In this study, lanthanide elements (Ln³⁺) and 2,3,5,6-tetrafluoro-1,4-benzenedicarboxylic acid (TFBDC) based metal-organic frameworks (MOFs) were synthesized by precipitation and diffusion-controlled precipitation methods. Powders insoluble in aqueous media and polar solvents were obtained. The microstructure and properties of Ln³⁺ MOFs were evaluated and discussed. X-ray diffraction (XRD) analysis, infrared (FTIR) spectroscopy, scanning electron microscopy (SEM) and fluorescence spectroscopy (FLS) were carried out to characterize Ln³⁺ MOF's crystallinity, the microstructure, chemical composition and optical properties.

Abstract: Lanthanide complexes [Ln (NO₃)₃(4’-(4-bromophenyl)-2,2’:6’,2’’-terpyridine)]; being Ln all the non radiative lanthanide elements (1 – 14), have been synthesized and characterized by IR, ¹H NMR, MALDI-MS and the X-ray structures of the La, Nd, Sm, Eu and Dy complexes, showing a linear comparison of the average M-O and M-N distances with the ionic radius or the number of f electrons of the lanthanides. The luminescence properties of complexes 4 (Nd), 5 (Sm), 6 (Eu), 8 (Tb), 9 (Dy) in the solid state and in the acetonitrile solutions of 5 (Sm) and 6 (Eu) are reported.

Abstract: Present article report synthesis and spectroscopic analysis of BiVO₄ nanophosphor doped with trivalent Eu ions. It was observed that BiVO₄ nanocrystals shows higher yield in comparison with the as-made nanocrystals on 266 nm laser excitation. On 266 nm excitation, emission composed of red dominated wide spectrum in the range of 400-950 nm was reported. Emission intensity enhanced five times on annealed sample than the counterpart. Time resolved analysis explores significant alteration in excited state relaxation process due to annealing. Detailed photo physics involved to improve optical emissions has also been explained.

Abstract: One lanthanide nitrate (Ln = Tb) with a novel three dimensional structure have been prepared through hydrothermal method. Single crystal X-ray diffraction structures were obtained. The compound crystallizes in the orthorhombic, Pnma space group. The lanthanide ions are eight-coordinate with six oxygen atoms coming from nitrate ions and two from bridge oxygen atoms. If the bridge oxygen atoms could be ignored, the compound can be described as a rare microporous 3D Lanthanide nitride with the open framework.

Abstract: The organic ligand sulfosalicylic acid (SSA) which was selected as molecular bridge for sensitization of terbium ions was modified by thionyl chloride (SOCl₂) and 3-ammonium propyl triethoxy silane (APTES) to obtain the hybrid precursor SSA-Si. Then the solution of Tb (NO₃)₃ was added in the presence of tetraethylorthosilicate (TEOS). The binary lanthanide organic/inorganic hybrid material was obtained. The ternary hybrid material was obtained by adding the solution of Tb (NO₃)₃ and polyurethane. We investigated the thermal stability and luminescence properties of hybrids and found that the ternary hybrid materials exhibit better thermal stability and stronger emission intensity. Furthermore, compared with the binary mesoporous material Tb-(SSA-Si)₃, the ternary mesoporous material Tb-(SSA-Si)₃-PU exhibits the characteristic emission of the Tb³⁺ ion with a higher luminescence intensity, suggesting that the introduction of polymer polyurethane into the mesoporous matrix is of benefit for the sensitization of Tb³⁺ luminescence, by replacing H₂O groups that can quench the luminescence of Tb³⁺ ion.

Abstract: Near infrared (NIR) emitting LaF₃:Ln³⁺ (Ln^3+→Nd³⁺, Er³⁺, Yb³⁺ and Ho³⁺) singly doped nanoparticles (NPs), with an average size of 5 nm, have been synthesized using simple co-precipitation route. Nanoparticles were functionalized with oleic acid. FTIR spectra revealed the prescience of chemisorbed oleic acid on the surface of nanoparticles. 10 wt % of LaF₃:Nd³⁺ nanoparticles were incorporated into epoxy by solution mixing method. The LaF₃:Nd³⁺-Epoxy Nanocomposites showed good transparency along with prominent NIR emissions at 880 nm, 1053 nm and 1330 nm on excitation at 575 nm.

Abstract: Lanthanide-doped semiconductors find usage in a wide variety of applications. In this work, Eu³⁺-doped rutile TiO₂ nanocrystals have been successfully prepared at room temperature by a sonochemical method. The nanocrystalline sample has been characterized by X-ray diffraction (XRD) and transmission electron microscopy (TEM) techniques. A possible mechanism is proposed to explain the formation of Eu³⁺-doped TiO₂ nanomateirals. Additionally, the characteristic emissions of Eu³⁺ can be found upon excitation in the region of TiO₂ absorption, indicating that an energy transfer from TiO₂ to Eu³⁺ occurs for the doped sample.

Abstract: To prepare nanoscale coordination polymers (NCPs) which can exhibit intense luminescence have attract an increasing interest. In this paper, we present the synthesis of a novel example of discus-like luminescent nanoscale Eu (III)-carboxylate coordination polymers. The organic ligand is a derivative of terephthalate (Na₂L) with a big side group. The Eu (III)-L NCPs was synthesized through microemulsion method, and the morphology can alter along with the changing of metal: ligand ratios. XRD results reveal that the self-assembled disk-like NCPs exhibit long-range ordered structures. The luminescent measurements showed that the resultant NCPs not only exhibits typical fluorescence of Eu (III), but also can maintain the inherent fluorescence of the ligands.

Abstract: In recent years, lanthanide-ion doped nanocrystals have attracted considerable attention for its promising applications in multiplexed biological labeling. These materials can convert near-infrared (NIR) light into visible and offer low autofluorescence, high resistance to photobleaching, high penetration depth and large anti-Stokes shifts. With the development of these techniques, the ability to manipulate multicolor output has become more important for its biological and photovoltaic applications. This review mainly focuses on the recent development of various approaches for the multicolor tuning of lanthanide-ion doped upconversion nanoparticles.