Enhancement of red to orange emission ratio of YPO4：Eu3＋,Ce3＋ and its dependence on Ce3＋ concentration

Eu3+ and Ce3+ co-doped YPO4 microspheres were synthesized by hydrothermal method without template. The emission spectra showed that the red emission centered at 618nm could be readily increased relatively to the orange emission centered at 590nm by controlling the doping concentration of Ce3+ ion. The investigation based on excitation spectra and decay curves demonstrated that the doped Ce3+ ions took two efficient energy transfers to Eu3+ ions and affected the lifetime of the emission states of Eu3+ ions so that the emission spectra of Eu3+ ion were accordingly tuned with the Ce3+ content increasing. This controllable red (5D0→7F2) to orange ( 5D0→7F1) emission ratio of YPO4:Eu3+,Ce3+ made it very promising for encoded anti-fake labels and bio-labels.     

Luminescence characteristics of Ca_4YO(BO_3)_3 doped with Bi~(3+),Dy~(3+) and Pr~(3+) ions

The photoluminescence(PL) properties of Ca4YO(BO3)3 doped with Bi3+,Dy3+,and Pr3+ ions were investigated.These compounds were prepared using a typical solid-state reaction.The excitation and emission spectra were measured using a spectrofluorometer.For Ca4YO(BO3)3:Bi3+,the excitation spectrum showed the bands at about 228,309,and 370 nm which correspond to the 1S0→1P1 transition and the 1S0→3P1 transition of Bi3+ ions.The emission band at 390 nm corresponded to the 3P1→1S0 transition of Bi3+ ions.For Ca4YO(BO3)3:Bi3+,Dy3+,energy transfer occurred from Bi3+ to Dy3+ somewhat.In Ca4YO(BO3)3:Bi3+,Dy3+,Pr3+,the excitation band at 367 nm was enhanced obviously due to the energy migration from Bi3+ to Pr3+,which converted efficiently the emission of semiconductor InGaN based light-emitting diode(LED).Therefore,the emission of Dy3+ ions was enhanced due to the energy migration from the process of Bi3+→Pr3+→Dy3+.It resulted in the good color rendering.     

Hydrothermal synthesis and photoluminescent properties of Li2Sr0.996SiO4:Pr0.0043+ phosphors for white-LED lightings

Red phosphors, Li2Sr0.996 Si O4: Pr3+0.004, with different hydrothermal conditions were prepared via hydrothermal synthesis and then heat-treatment. The chemical structures of the phosphors were identified with X-ray diffraction(XRD). Surface morphological features were observed by scanning electron microscopic(SEM) investigation. Spectra of excitation and emission for the phosphors were also obtained by a spectrophotometer. Results showed that the optimum conditions were as follows: p H value of solution was 1–2, reaction temperature was at 180 oC for 24 h. The as-prepared phosphors exhibited two excitation dominant peaks at 451 and 486 nm, attributed to transitions of 3H4→3P2 and 3H4→3P0 of Pr3+, respectively. A narrow emission peak at 610 nm corresponded to the energy level transition of 3P0→3H6 of Pr3+ under excitation of light at 451 nm, which indicated promising candidate red phosphors for blue LED chips.     

Optical and thermoluminescence properties of Lu2Si2O7：Pr single crystal

Single crystal of Lu2Si2O7:Pr was grown by Czochralski method. Transmittance, photoluminescence excitation (PLE) and photo-luminescence (PL) spectra, X-ray excited luminescence (XEL) and fluorescence decay time spectra of the sample were measured and discussed to investigate its optical characteristics. The crystal structure of the as grown Lu2Si2O7:Pr was confirmed to be C2/m. There was a broad absorption peaking at 245 nm in the region from 200-260 nm. The PL spectrum was dominated by fast 3PJ→3HJ band peaking at 524 nm. The XEL spectrum was dominated by the fast 5d14f1→4f2 emission peaking at 265 nm. The 2D (temperature-intensity) and 3D (temperature-wavelength-intensity) thermally stimulated luminescence (TSL) spectra were measured. The Pr3+ ion was found to be the recombination center during the TSL process. Three obvious traps were detected in LPS:Pr single crystal with energy depth at 1.06, 0.78 and 0.67 eV.     

Luminescence properties of calcium tungstate activated by lanthanide(Ⅲ) ions

Calcium tungstate phosphors activated by the Ln3+ ions(Ln=Pr, Nd, Tb, Yb) were synthesized by a traditional high-temperature solid-state method. The crystal structures and morphologies of the products were characterized by scanning electron microscopy(SEM), X-ray powders diffraction(XRD) and infrared spectra(FT-IR). The samples were found to show luminescence properties(down-conversion, DC, at excitation wavelength 254 nm and up-conversion, UC, at excitation wavelength 980 nm). CaWO4 doped with Tb3+/Yb3+ showed green DC and UC luminescence characteristic of Tb(III) ion in the range of 470–660 nm, corresponding to the 5D4→7F6,5,4,3,2 electronic transition. CaWO4 doped with Pr3+/Yb3+ showed week blue, green and red(DC and UC) luminescence of Pr(III) ion, in the wavelength region of 450–700 nm. Emission peaks were ascribed to the 3P1→3H4,5,6, 3P0→3H4,5,6, 3P1→3F2 and 3P0→3F2 transitions, respectively. CaWO4 doped with Nd3+/Yb3+ phosphor emitted orange UC luminescence at 450–690 nm(2P3/2→4I15/2, 4G7/2→4I9/2,11/2,13/2) and strong near-infrared UC luminescence at 720–900 nm(4F7/2+4S3/2→4I9/2, 4F5/2+2H3/2→4I9/2, 4F3/2→4I9/2) which is the characteristic of Nd(III) ion.     

Pr~(3+)-doped Li_2SrSiO_4 red phosphor for white LEDs

Novel red phosphors,Li2Sr1-1.5xSiO4:xPr3+(x=0.002,0.003,0.004,0.005,0.006 and 0.008),were synthesized by conventional solid state reaction and the luminescent properties were investigated.The as-prepared phosphors showed red emission at 610 nm under excitation of blue light at 452 nm,indicating that they were promising candidates for red phosphors in the fabrication of white LEDs via blue LED chips.Their excitation bands at 452,476 and 487 nm were attributed to transitions of 3H4→3P2,3H4→3P1+1I6,3H4→3P0 of Pr3+ ion.The red emissions at 606 and 610 nm were originated from the 3P0-3H6 and 1D2-3H4 transitions of Pr3+.The optimum doping concentration of Pr3+ in Li2Sr1-1.5xSiO4:xPr3+ was determined to be x=0.004.With the concentration of Pr3+ over x=0.004,the fluorescence intensity of Li2Sr1-1.5xSiO4:xPr3+ decreased,indicating the concentration quenching occurred.     

Green up-conversion luminescence in Yb^3＋-Pr^3＋ co-doped BaRE2ZnO5（RE=Y,Gd）

Yb3＋and Pr3＋co-doped BaRE2 ZnO5（RE=Y,Gd） up-conversion（UC） phosphors were successfully synthesized by a modified sol-gel method.The processing parameters and optimal concentration of Pr3＋and Yb3＋were determined.The structures and luminescent properties of samples were characterized by X-ray diffraction（XRD） and photoluminescence spectra（PL）.With the excitation of 980 nm laser diode,UC spectra showed five prominent emission bands centered at 484,514,546,656 and 670 nm,which were attributed to the1I6 →3H4,3P1 →3H4,3P0 →3H5,3P0 →3F2 and3P0 →3F3 transitions of Pr3＋,respectively.In the light of the pump power dependence,the possible UC mechanism in Yb3＋and Pr3＋co-doped BaRE2 ZnO5（RE=Y,Gd） was proposed and discussed.     

Effect of Yb3+ concentration on upconversion luminescence of AlON:Er3+ phosphors

AlON:1.6 mol.%Er3+, x mol.%Yb3+(x=0, 2.6, 3.1, 3.6, 4.1, 4.6) phosphors were synthesized successfully by aluminothermic reduction and nitridation(ATRN) method and characterized by X-ray diffraction(XRD), scanning electron microscopy(FESEM) and upconversion photoluminescence(UCPL) emission spectra. Under the excitation of diode laser 980 nm, the green(556 nm) and red(655 nm) upconverted emissions were observed, attributed to the 4S3/2→4I15/2 and 4F9/2→4I15/2 transition of Er3+respectively. The emission intensity increased with increasing Yb3+ concentration due to the energy transfer(ET) between Yb3+ and Er3+. The upconverted emission reached the highest as x=3.6, and was pump-power dependent involving a two-photon process.     

Hydrothermal synthesis,structure study and luminescent properties of YbPO₄:Tb³⁺ nanoparticles

YbPO4:Tb3+ were synthesized by mild hydrothermal method.The luminescent properties,morphologies and structure of the obtained powders were characterized by photoluminescence(PL) spectra,FESEM,X-ray diffractometer(XRD) and FTIR.The results showed that the prepared YbPO4:Tb3+ nanoparticles were pure tetragonal phase and the average grain size varied with increasing of Tb3+ concentration.Hydrothermal temperature was revealed to be the key factor to enhance the emission intensity of YbPO4:Tb3+ phosphors.The spherical nanoparticles could be effectively excited by near UV(369 nm) light and exhibited green performance at 543 nm(5D4→7F5),489 nm(5D4→7F6) and 586 nm(5D4→7F4).The CIE chromaticity was calculated to be x=0.298,y=0.560.The YbPO4:Tb3+ nanoparticles exhibited potential to act as UV absorber for solar cells to enhance the conversion efficiency.     

Synthesis and characterization of nano-sized YAG:Ce,Sm spherical phosphors

YAG:Ce,Sm spherical phosphors were synthesized by malic acid sol-gel method.The formation process of crystalline was characterized by X-ray diffraction(XRD)technique.The influence of Sm3+ doping on the luminescent intensity and the morphology of phosphors were studied by fluorescence spectrum and scanning electron microscopy(SEM)techniques,respectively.The results indicated that the size of spherical powders was about 100 nm calcined at 1200 ℃ for 3 h.The emission spectra of phosphors showed gradual red-shift from 525 to 540 nm with the increase of doping concentration of Sm3+ ion.A broadband emission spectrum of Ce3+ ion appeared at 540 nm,and a series of emission peaks corresponding to the 4G5/2→6HJ transition of Sm3+ ion also appeared at 617 nm with the doping of Sm3+.The red component of YAG:Ce phosphors increased with the doping of Sm3+.     

熔炼次数对M17返回料合金成分、组织和性能的影响

实验结果表明,M17铸造高温合金(%:0.16C、8.79Cr、5.79A1、4.93Ti、3.29Mo、15.20Co、0.78V、0.015B、0.073Zr、0.002S、0.001P、0.001 1O、0.001 0N)经25 kg真空感应炉返回重熔后,Si含量随重熔次数的增加而略有增加,合金中主要元素和其它杂质元素S、P、H的含量变化不大,而氧、氮略有增加;合金中初生碳化物由新合金中的草书体逐渐向返回合金块状转变,初生碳化物的遗传性堵塞合金凝固时的补缩通道,使返回料合金的疏松倾向增大,高温塑性下降较大。     

Shijiazhuang will Build the World's Biggest Replacingcopper-with-aluminum Cable Production Base

正Shijiazhuang City will build the world’s biggest replacing-copper-with-aluminum cable production base,the annual output value can reach 100 billion yuan,in the future it will develop replacing-copper-with-aluminum highend industry cluster.This piece of news was learned by the reporter at the Rare Earth highiron Aluminum Alloy[Nonferrous Business Opportunity:Aluminum alloy door]Cable Conductor New Technology Application Seminar held at the provincial capital.     

Chongqing is Preparing to Set Up Nonferrous Metal Exchange,in a Bid to Become the Transit Place of Kazakhstan Copper

正Since the beginning of Chongqing’s upgrading to a municipality directly under the Central Government,Chongqing City has established direct friendly relationship with Almaty,Kazakhstan,and carried out a series of cooperation in commerce and trade,and culture     

Guangxi Baise Extends Industrial Chain to Combat Loss in Aluminum Business

正"For each tonne of aluminum being produced,the upstream enterprise on the aluminum industrial chain will suffer loss about 2000yuan."Said Liang Xiao,Deputy Director of Pingguo Industrial Park Management Committee under the Guangxi Baise City,one of the four major aluminum industry bases in China,on August 11.Extending aluminum     

JOURNAL OF IRON AND STEEL RESEARCH INTERNATIONAL ANNUAL CONTENTS Volume 21(2014)

正~~     

Chinalco Straightened Out Copper Assets,and Delegated Stock Equity of Yunnan Copper

正Immediately after the news that Chinalco transferred 58%stock equity of Yunnan Copper Group to its wholly-owned subsidiary China Copper Corporation Limited free of charge was disclosed on July 9,many individual investors couldn’t help but to think:Does it mean China Copper Corporation Limited will assemble assets for overall listing?At present,among main copper business companies under China Copper Corporation     

The Development and Reform Commission Encourages Private Capital to Enter Geological Prospecting Field

正At the press conference recently held by the National Development and Reform Commission under the theme"Deepen Reform in Investment AuditApproval System",when answering questions from reporters,Huang Min,Director of the Department of Fixed Assets Investment of the National Development and Reform Commission,said that in the future it would continue to intensify efforts in geological prospecting,and actively guide social capital to enter this field.     

Guangxi's first Nickel Industry Development Research Report Was Released

正Recently,Guangxi Metallurgical Research Institute,a subsidiary of Guangxi Nonferrous Metals Group,completed survey on laterite and related manufacturers in the region,by combining the current development status of laterite both at home and abroad,it compiled Guangxi’s first"Research Report on the Development of Guangxi Nickel Industrial Chain"which adopted laterite as the study subject.This report expounded on the current     

China’s Major Non-ferrous Metals Imports & Exports(End of September. 2014)

正~~     

China's Major Non-ferrous Metals Imports & Exports

正~~