National Engineering Research Center for Ionic Rare Earth

Ganzhou, China

National Engineering Research Center for Ionic Rare Earth

Ganzhou, China
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Ye X.,Jiangxi University of Science and Technology | Ye X.,National Engineering Research Center for Ionic Rare Earth | Luo Y.,Jiangxi University of Science and Technology | Liu S.,Jiangxi University of Science and Technology | And 2 more authors.
Journal of Alloys and Compounds | Year: 2017

A series of novel Er3+ doped and Er3+/Yb3+ co-doped Ba3Lu4O9 phosphors were synthesized by a simple high-temperature solid-state reaction method. The crystal structure and morphology of the samples were identified by XRD and SEM analysis. Under 980 nm laser diode excitation, the green (at 537 nm and 560 nm) and red (at 660 nm) UC emission were observed, which could be attributed to the (2H11/2, 4S3/2)→4I15/2 and 4F9/2 → 4I15/2 transitions, respectively. The UC luminescence can be finely tuned from green to dark-yellow light to some extent by increasing Yb3+ doping concentration. The sintering temperature and doping concentration of Ba3Lu4-x-yO9: x Er3+, y Yb3+ were optimized to x = 0.1 and y = 0.6 at 1550 °C. The emission intensity ratio of Green/Red keeps declining monotonically with increasing Er3+ or Yb3+ concentration, which is due to the cross-relaxation effect and cooperative energy transfer between the two neighboring Er3+ ions-as well as back energy transfer from Er3+ to Yb3+ ions. Based on the pump-power dependence and UC luminescence decay curves, the energy level diagram and the possible energy transfer mechanism of Er3+ doped as well as Er3+/Yb3+ co-doped system were investigated in detail. In addition, according to the energy gap law, the possibilities of non-radiative transition between parts of energy levels of Er3+ ions were calculated. © 2017 Elsevier B.V.


Liu S.,Jiangxi University of Science and Technology | Zhou M.,Jiangxi University of Science and Technology | Ye X.,Jiangxi University of Science and Technology | Ye X.,National Engineering Research Center for Ionic Rare Earth | And 2 more authors.
RSC Advances | Year: 2017

A series of Ba3Lu4O9:Er3+/Yb3+ (EYBLO) phosphors co-doped with F- ions were synthesized by a simple solid-state reaction method. The results showed that the primary rhombohedral structure was maintained and the crystal lattice began to shrink when F- ions were introduced into the host matrix to occupy the O2- site. The agglomerations and the impurities (OH- and CO2) with higher phonon energy on the sample surface could be minimized and the sample crystallinity could be improved. Under 980 nm laser diode excitation, the green and red UC emissions of the EYBLO:0.4F- sample show nearly 5- and 7.5-fold enhancements in contrast to F--free EYBLO. The upconversion luminescence can be finely tuned from yellow to red light to some extent by increasing F- concentration. Based on pump-power dependence and decay lifetime analysis, the energy level diagram was illustrated and the upconversion energy-transfer mechanism was discussed. The green and red emission enhancements are attributed to the modification of the local crystal field of Er3+ ions and reduction of crystal site symmetry. The cross-relaxation and back-energy-transfer processes play an important role to enhance the red/green UC emission intensity ratios. The fluorescence intensity ratio technique was employed to investigate the temperature sensing behavior of the synthesized phosphors. The temperature sensing properties can be enhanced by doping of F- ions, and the maximum sensitivity is found to be 44.57 × 10-4 K-1 at 523 K. It is promising to provide an alternative approach for enhancing UC luminescence and the temperature sensitivity in oxide matrixes and then obtain high-quality optical temperature-sensing materials by simply co-doping F- ions. © 2017 The Royal Society of Chemistry.


Liu S.,Jiangxi University of Science and Technology | Chen M.,Jiangxi University of Science and Technology | Niu H.,Jiangxi University of Science and Technology | Ye X.,Jiangxi University of Science and Technology | And 3 more authors.
Guangxue Xuebao/Acta Optica Sinica | Year: 2017

A series of Li+ doped SrLu2O4:Ho3+/Yb3+ phosphors are prepared with high-temperature solid-state reaction method. The Li+ doped samples maintain the primary orthorhombic structure. The Li+ ions can be introduced into the host lattice through the approach of substitutional doping and interstitial doping. By adding appropriate Li+ ions to the samples, the agglomeration of samples can be minimized and the average diameter of particles is about 3 μm. The impurities (OH- and CO3 2-) with high phonon energy can be reduced, which reduces the quenching centers and increases upconversion emission intensity. The intense green emission and weak red emission are observed under the excitation of the 980 nm laser, which are attributed to the 5F4, 5S2→5I8 and 5F5→5I8 transitions, respectively. With the introduction of Li+ ions to the SrLu2O4:Ho3+/Yb3+ sample, the upconversion emission is found to be significantly enhanced, which is attributed to the modification of local crystal field symmetry around Ho3+ ions by Li+ doping. Compared with other alkali-metal-ion dopings, the Li+ doped sample has the strongest luminescence intensity due to the smallest ionic radius and the strongest electronegativity of Li+ ions. The analysis result of pump-power dependence show that the green and red emissions are both involved in a two-phonon process. © 2017, Chinese Lasers Press. All right reserved.


Pan T.,Jiangxi University of Science and Technology | Pan T.,Guangdong Institute of Microbiology | Pan T.,National engineering research center for ionic rare earth | Liu C.,Jiangxi University of Science and Technology | And 6 more authors.
Environmental Science and Pollution Research | Year: 2017

A recent work has shown that hydrophobic organic compounds solubilized in the micelle phase of some nonionic surfactants present substrate toxicity to microorganisms with increasing bioavailability. However, in cloud point systems, biotoxicity is prevented, because the compounds are solubilized into a coacervate phase, thereby leaving a fraction of compounds with cells in a dilute phase. This study extends the understanding of the relationship between substrate toxicity and bioavailability of hydrophobic organic compounds solubilized in nonionic surfactant micelle phase and cloud point system. Biotoxicity experiments were conducted with naphthalene and phenanthrene in the presence of mixed nonionic surfactants Brij30 and TMN-3, which formed a micelle phase or cloud point system at different concentrations. Saccharomyces cerevisiae, unable to degrade these compounds, was used for the biotoxicity experiments. Glucose in the cloud point system was consumed faster than in the nonionic surfactant micelle phase, indicating that the solubilized compounds had increased toxicity to cells in the nonionic surfactant micelle phase. The results were verified by subsequent biodegradation experiments. The compounds were degraded faster by PAH-degrading bacterium in the cloud point system than in the micelle phase. All these results showed that biotoxicity of the hydrophobic organic compounds increases with bioavailability in the surfactant micelle phase but remains at a low level in the cloud point system. These results provide a guideline for the application of cloud point systems as novel media for microbial transformation or biodegradation. © 2017 Springer-Verlag Berlin Heidelberg


Luo Y.,Jiangxi University of Science and Technology | Jiang J.-Q.,Jiangxi University of Science and Technology | Hou D.-J.,Jiangxi University of Science and Technology | You W.-X.,Jiangxi University of Science and Technology | And 2 more authors.
Faguang Xuebao/Chinese Journal of Luminescence | Year: 2015

Na2TiF6: Mn4+ red phosphors with different Mn4+ doping mole fraction were synthesized by the co-precipitation method. Structure, morphology, photoluminescence excitation and emission spectra as well as decay curve of Na2TiF6: Mn4+ phosphors were studied by X-ray diffraction (XRD), scanning electron microscope (SEM), Fourier transform infrared spectroscopy (FT-IR) and fluorescence spectrometer. As-prepared Na2TiF6: Mn4+ phosphors have hexagonal structures. Under 460 nm excitation, intense red emissions corresponding to 2Eg-4A2 transitions of Mn4+ are observed. The optimum doping mole fraction of Mn4+ is 4.77% and the quantum efficiency is 74% for this phosphor. The chromaticity coordinates of the Na2TiF6: Mn4+ phosphors are (0.681, 0.317). Decay curve of 2Eg state for as-prepared Na2TiF6: Mn4+ sample fits the second order exponential behavior, and the average lifetime is 3.148 ms. © 2015, SCIENCE PRESS. All right reserved.


Lan Q.,Jiangxi University of Science and Technology | Lan Q.,National Engineering Research Center for Ionic Rare Earth | Huang Z.,Jiangxi University of Science and Technology | Xie F.,Jiangxi University of Science and Technology | And 2 more authors.
Zhongguo Xitu Xuebao/Journal of the Chinese Rare Earth Society | Year: 2015

Fe3+ has an intensive tendency of hydrolysis and is easy to form complexes with other ions, therefore the solvent extraction system containing Fe3+ is very complex. Using P204 or N235 to remove Fe3+ in rare earth extraction system, the organic phase with Fe3+ was stripped by hydrochloric acid, its stripping rate was low, and it had a deep influence on the ability of the extraction agents. In extraction system of P507-N235 hydrochloric acid, the Fe3+ in low acidity and the complex of FeCl4- formed in high acidity were extracted by p507 and N235, respectively, and the extraction rate could reach 99% and was hard to stripping. The removal of Fe3+ from the organic phase was investigated by using a complexing method consisting of oxalic acid and EDTA. The results showed that the stripping rate of Fe3+ was too low by using complexing method of oxalic acid, therefore the oxalic acid couldn't be used for the removal of Fe3+. At temperature of 25 ℃, stripping time of 14 min, feed phase proportion of 1∶1, the stripping rate of Fe3+ could reach 97.51% by using complexing method of EDTA, and the concentration of Fe3+ in organic phase could decrease to 0.002 g·L-1 after a four-stage cross-flow stripping. ©, 2015, Chinese Rare Earth Society. All right reserved.


Ye X.,Jiangxi University of Science and Technology | Ye X.,National Engineering Research Center for Ionic Rare Earth | Li Q.,Jiangxi University of Science and Technology | Wu D.,Jiangxi University of Science and Technology | And 2 more authors.
Kuei Suan Jen Hsueh Pao/Journal of the Chinese Ceramic Society | Year: 2015

As an important binary system of BaO-Lu2O3-SiO2 ternary system, BaO-SiO2 system was assessed via the thermodynamic calculation by the CALPHAD method based on experimental phase diagram and the relevant thermodynamic data. The Gibbs energy of high temperature solution was determined by an ionic two-sublattice model as (Ba2+)P(O2-,SiO4 4-, SiO2 0)Q. The calculated Gibbs energies of seven intermediate phases (i.e., Ba2SiO4, BaSi2O5, BaSiO3, Ba2Si3O8, Ba3Si5O13, Ba3SiO5, and Ba5Si8O21) are in reasonable agreement with the experimental data. In the SiO2-rich part, the optimized liquidus is in agreement with the experimental data and the calculated activities of SiO2 reproduce the experimental results within the error limits. The calculated activities of BaO differ from the experimental data in range of 50% (mole fraction) to 80% BaO, which may be caused by the experimental error. The liquid Gibbs energy of mixing was also calculated. The obtained self-consistent phase diagram and thermodynamic data can be used for single-phase phosphor research and related metallurgical systems. © 2015, Chinese Ceramic Society. All right reserved.


Ye X.-Y.,Jiangxi University of Science and Technology | Ye X.-Y.,National Engineering Research Center for Ionic Rare Earth | Li Q.,Jiangxi University of Science and Technology | Luo Y.,Jiangxi University of Science and Technology | And 2 more authors.
Materials Science Forum | Year: 2016

Only one intermediate compound Ba3Lu4O9 was identified at 1373, 1573 and 1773K in the BaO-Lu2O3system in present work.Based on the available experimental phase diagram and relevant thermodynamic data, BaO-Lu2O3 binary system was optimized and calculated by using CALPHAD method. The Gibbs free energy of high temperature solution was described by an ionic two-sublattice model as (Ba2+,Lu3+)P(O2-)Q. The calculated phase diagram, Gibbs energy of intermediate phaseBa3Lu4O9and Gibbs energy of mixing agree well with experimental results within error limits. The study will offer theoretical basis for further research of the phosphor matrix system of BaO-Lu2O3-SiO2, but also provide new idea for the phase diagram and thermodynamic research on related metallurgical slags, refractories, high-temperature superconductivity material systems. © 2016 Trans Tech Publications, Switzerland.


Wu D.,Jiangxi University of Science and Technology | Wu D.,National Engineering Research Center for Ionic Rare Earth | Ye X.,Jiangxi University of Science and Technology | Ye X.,National Engineering Research Center for Ionic Rare Earth | And 4 more authors.
Xiyou Jinshu/Chinese Journal of Rare Metals | Year: 2016

(Sc,Y)(V1-xBx)O4-x:Eu3+ (0≤x≤0.5) phosphors were synthesized by solid state reaction at 1200℃ for 3 h. Luminescence properties, structure and morphology of samples were investigated by fluorescence spectrophotometer, X-ray diffraction(XRD) and scanning electron microscope(SEM), respectively. The results showed the main emission peak was located at 620 nm under the UV excitation of 365 nm, which was due to 5D0→7F2 transitions of Eu3+. The luminescence intensity was 1.6 times relative to Sc0.73Y0.2VO4:Eu0.07 3+ phosphors when the x=0.1. There were a strong broad absorption band and a weak emission band with peak at 337 and 396 nm, respectively, when monitored at 620 nm. The samples doped with boron maintained the body-centered tetragonal structure of (Sc,Y)VO4:Eu3+ and the morphology essentially unchanged. The particles showed uniform distribution without visible aggregation. The internal quantum efficiency was 2 times higher when excited at 397 nm and the relative luminous intensity maintained 92% as the temperature was raised to 200℃. The samples showed high internal quantum efficiency and low thermal quenching, which was suitable for the UV-pumped white light emitting diode(LED) as red phosphor. © Editorial Office of Chinese Journal of Rare Metals. All right reserved.


Huang X.,Jiangxi University of Science and Technology | Li Q.,Jiangxi University of Science and Technology | Yang M.,Jiangxi University of Science and Technology | Luo Y.,Jiangxi University of Science and Technology | And 4 more authors.
Zhongguo Xitu Xuebao/Journal of the Chinese Rare Earth Society | Year: 2016

With the development of rare-earth materials, neodymium oxide with large particles has been widely used in high technology field. Study on the decomposition of neodymium oxalate to neodymium oxide benefits the preparation of neodymium oxide with excellent performance. The thermal decomposition of neodymium oxalate with large particles was investigated by TG/DTG/DTA in the present study. The activation energy E was calculated with Ozawa equation and Starink equation, as well as the reaction mechanism function deduced by Coats-Redfern integral method. At a heating rate of 10℃·min-1, neodymium oxalate lost water of hydration from room temperature to 397℃; anhydrous neodymium oxalate decomposed to Nd2O2CO3 between 397 and 584℃; Nd2O2CO3 decomposed to Nd2O3 in the temperature range between 584 and 770℃. The TG/DTG/DTA curves moved to the high-temperature sides with increasing the heating rate. The higher the heating rate, the higher corresponding temperature to reach the same mass loss rate was. With the maximum heating rate applied, the mass loss rate in the DTG curve was obviously higher, the peak area in the DTA curve was larger as well as the absolute value of enthalpy under the same temperature was bigger. From anhydrous neodymium oxalate to Nd2O2CO3, the decomposition energy was 130.10~187.8 kJ·mol-1. And the reaction was in accordance with the three-dimensional diffusion model. From Nd2O2CO3 to Nd2O3, the decomposition energy was 57.40~81.83 kJ·mol-1. © 2016, Editorial Office of Journal of the Chinese Society of Rare Earths. All right reserved.

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