Red-emitting CaWO4:Eu^(3+),Tm^(3+)phosphor for solid-state lighting:Luminescent properties and morphology evolution  

作　　者：L.X.Lovisa I.M.P.da Silva A.A.G.Santiago M.Siu Li E.Longo C.A.Paskocimas M.R.D.Bomio F.V.Motta 

机构地区：[1]Institute of Physics and Chemistry.Federal University of Itajubd(UNIFEI),Itajubd,MG,37500-903,Brazil [2]LSQM-Laboratory of Chemical Synthesis of Materials-Department of Materials Engineering,Federal University of Rio Grande Do Norte,P.O.Box 1524,59078-900,Natal RN,Brazil [3]IFSC,USP,Av.Trabalhador Sao Carlense,400,CEP 13566-590,Sao Carlos,SP,Brazil [4]CDMF-LIEC,UFSCar,P.O.Box 676,13565-905,Sao Carlos.SP,Brazil

出　　处：《Journal of Rare Earths》2022年第2期226-233,I0002,共9页稀土学报（英文版）

基　　金：Project supported by National Council for Scientific and Technological Development-CNPq(303,604/2018-2);the Coordination for the Improvement of Higher Education Personnel(CAPES)-Brazil。

摘　　要：CaWO_(4):xEu^(3+),yTm^(3+)crystals were obtained by facile synthesis at low temperature by the microwaveassisted hydrothermal method(MAH).The phase formation,morphology,luminescent properties and ene rgy transfer were investigated.The X-ray diffraction(XRD)re sults show the formation of a scheelitelike tetragonal structure without the presence of secondary phases.The growth mechanism of hierarchical micro structures based on self-assembly and Ostwald-ripening processes was evaluated,obtaining different types of morphologies.The luminescence spectra of CaWO_(4):Eu^(3+),Tm^(3+)at 325 nm excitation show the predominance of red emission at the 5 D0→7 F2(Eu^(3+))transition at 624 nm.This feature signals dominant behavior of the electric dipole type.The presence of Tm^(3+)is notably evident in the absorption spectra by the related excitation transitions:3 H6→1 G4,3 H6→3 F3 and 3 H6→3 H4.Color parameters are discussed to characterize CaWO_(4):Eu^(3+),Tm^(3+)emission.The study of the emission spectrum as a function of the concentration of Eu^(3+)(x mol%)and Tm^(3+)(y mol%)indicates that the CaWO_(4):Eu^(3+),Tm^(3+)phosphors show stronger red emission intensity and exhibit the CIE value of x=0.63 and y=0.35.The photoluminescence results show 97%high color purity for CaWO_(4):4 mol%Eu^(3+),a high CRI(92%)and a low CCT of 1085 K.These results demonstrate that the CaWO_(4):Eu^(3+),Tm^(3+)red phosphors are promising as color converters for application in white light-emitting diodes and display devices.

关 键 词：CaWO_(4):Eu^(3+) Tm^(3+)microwave-assisted hydrothermal method Photoluminescence Red phosphor Rare earths 

分 类 号：TN312.8[电子电信—物理电子学] TQ422[化学工程]