Synthesis of agglomerate-free YAG: Ce3+ phosphors by co-precipitation and low temperature spray pyrolysis

Conference Name:2011 International Symposium on Advanced Packaging Materials, APM 2011. Conference Address: Xiamen, China. Time:October 25, 2011 - October 28, 2011.Y3-xCexAl5O12 (YAG: Ce 3+) phosphor particles were prepared by a new method called co-precipitation and low temperature spray pyrolysis (CP-LTSP) with oxalic acid and ammonia as precipitant. It corresponds to the first-step chemical liquid reaction, the second step dehydration and partial decomposition of precipitation droplets at 250°C and then heating at 1100°C or above. Spherical as-prepared particles and agglomerate-free YAG: Ce3+ phosphor particles were obtained respectively. Pure YAG phase could be formed after LTSP at 250°C and then annealing at 1100°C for 4 h. The emission spectra and XRD patterns of YAG: Ce3+ phosphor particles indicated that the optimum doping concentration of Ce3+ was 0.06. The emission intensity increased with the increase of annealing temperature. As a result, the YAG: Ce3+ phosphor particles without optimization annealed at 1550°C for 4 h had the similar emission intensity (96%) of the commercial phosphor by the solid-state method. ? 2011 IEEE

Synthesis of ultrafine spherical YAG : Eu3+ phosphors by MOCVD

KeyWords Plus: YAG-TB PHOSPHOR; LUMINESCENT PROPERTIES; COMBUSTION PROCESS; SPRAY-PYROLYSIS; CE PHOSPHOR; PHOTOLUMINESCENCE; PARTICLES; MORPHOLOGY; POWDERS 通讯作者地址: Zeng, RJ (通讯作者), Xiamen Univ, Coll Mat Sci, Sinning S Rd 22, Xiamen 361005, Peoples R China 地址: 1. Xiamen Univ, Coll Mat Sci, Xiamen 361005, Peoples R China 电子邮件地址: [email protected] Europium-doped yttrium aluminum garnet (YAG:Eu3+) phosphor powders, with uniform diameters of about 1 mu m, have been prepared by metallorganic chemical vapor deposition (MOCVD). The metal-organic precursors have been characterized by thermogravimetry-differential scanning calorimeter (TG-DSC). The phosphor powders have been identified by X-ray diffraction (XRD), scanning electron microscope (SEM) and photoluminescence measurements. It shows that the YAG:EU3+ particles annealed at 1473 K for 3 h are nonaggregated and spherical, the diameter of particles is in the range of 1-2 mu m. Phase-pure YAG which is of spherical shaped particles have been obtained and observed good luminescence property. Three major emission peaks were observed at 589, 594, and 607 nm

A novel red phosphor NaLa4(SiO4)(3)F Eu3+

通讯作者地址: Feng, G (通讯作者), Xiamen Univ, Dept Mat Sci & Engn, Xiamen 361005, Peoples R China 地址: 1. Xiamen Univ, Dept Mat Sci & Engn, Xiamen 361005, Peoples R China 2. Jingdezhen Ceram Inst, Sch Mat Sci & Engn, Jingdezhen 333001, Peoples R ChinaA novel red phosphor NaLa4(SiO4)(3)F Eu3+ was synthesized by the conventional solid-state reaction at 950 C for the first time The luminescence properties of NaLa4(SiO4)(3)F Eu3+ were investigated and the critical concentration of the activator concentration (Eu3+) was found to be 0 1 mol per formula unit The phosphor presented red luminescence under the ultraviolet excitation of 254 or 395 nm attributed to the transitions from D-5(0) excited states to F-7(J) (J=0-4) ground states of Eu3+ ions The results indicated that this newly developed phosphor could find applications in tricolor fluorescent lamp phosphor-liquid crystal displays and white lighting devices utilizing GaN-based excitation in the near UV (C) 2010 Elsevier BV All rights reserve

Search for dark matter produced in association with bottom or top quarks in √s = 13 TeV pp collisions with the ATLAS detector

A search for weakly interacting massive particle dark matter produced in association with bottom or top quarks is presented. Final states containing third-generation quarks and miss- ing transverse momentum are considered. The analysis uses 36.1 fb−1 of proton–proton collision data recorded by the ATLAS experiment at √s = 13 TeV in 2015 and 2016. No significant excess of events above the estimated backgrounds is observed. The results are in- terpreted in the framework of simplified models of spin-0 dark-matter mediators. For colour- neutral spin-0 mediators produced in association with top quarks and decaying into a pair of dark-matter particles, mediator masses below 50 GeV are excluded assuming a dark-matter candidate mass of 1 GeV and unitary couplings. For scalar and pseudoscalar mediators produced in association with bottom quarks, the search sets limits on the production cross- section of 300 times the predicted rate for mediators with masses between 10 and 50 GeV and assuming a dark-matter mass of 1 GeV and unitary coupling. Constraints on colour- charged scalar simplified models are also presented. Assuming a dark-matter particle mass of 35 GeV, mediator particles with mass below 1.1 TeV are excluded for couplings yielding a dark-matter relic density consistent with measurements