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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. Source


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. Source


Ye X.,Jiangxi University of Science and Technology | Ye X.,National Engineering Research Center for Ionic Rare Earth | Huang X.,Jiangxi University of Science and Technology | Hou D.,Jiangxi University of Science and Technology | And 6 more authors.
Physica B: Condensed Matter | Year: 2016

Bi3+, PO43- and BO33- doped Sc0.73Y0.2VO4:Eu0.073+ phosphors were synthesized by solid state reaction at 1200 °C. The structure, morphology and luminescence properties were investigated. The synthesized phosphors show narrow particle distribution with average size around 2 μm. Under 365 nm excitation, integrate emission intensity increases after doping with Bi3+, PO43- and BO33-. The optimal doping concentrations are 1%, 20%, 10% for Bi3+, PO43- and BO33-, respectively. The thermal stability is greatly improved, especially for BO33- doped sample, whose intensity is about 92% of its original intensity even at 200 °C. © 2016 Elsevier B.V. All rights reserved. Source


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. Source


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. Source

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