Red-emitting CaWO4∶Eu3+,Tm3+ phosphor for solid-state lighting:Luminescent properties and morphology evolution

• 作者: L.X.Lovisa J.M.P.da Silva A.A.G.Santiago M.Siu Li E.Longo C.A.Paskocimas M.R.D.Bomio F.V.Motta
• 来源期刊: 稀土学报（英文版）
• 年，卷（期）: 2022,（2）
• 所属期刊栏目: SPECTROSCOPY, LUMINESCENCE AND PHOSPHORS
• 页码范围: 226-233
• 页数: 8页
• 语种: 英文

摘要

CaWO4∶xEu3+,yTm3+ crystals were obtained by facile synthesis at low temperature by the microwave-assisted hydrothermal method (MAH).The phase formation,morphology,luminescent properties and energy transfer were investigated.The X-ray diffraction (XRD) results show the formation of a scheelite-like tetragonal structure without the presence of secondary phases,The growth mechanism of hierar-chical microstructures based on self-assembly and Ostwald-ripening processes was evaluated,obtaining different types of morphologies.The luminescence spectra of CaWO4∶Eu3+,Tm3+ at 325 nm excitation show the predominance of red emission at the 5D0 → 7F2 (Eu3+) transition at 624 nm.This feature signals dominant behavior of the electric dipole type.The presence of Tm3+ is notably evident in the absorption spectra by the related excitation transitions:3H6 → 1G4,3H6 → 3F3 and 3H6 → 3H4.Color parameters are discussed to characterize CaWO4∶Eu3+,Tm3+ emission.The study of the emission spectrum as a function of the concentration of Eu3+ (x mol％) and Tm3+ (y mol％) indicates that the CaWO4∶Eu3+,Tm3+ phosphors show stronger red emission intensity and exhibit the CIE value of x =0.63 and y =0.35.The photo-luminescence results show 97％ high color purity for CaWO4∶4 mol％Eu3+,a high CRI (92％) and a low CCT of 1085 K.These results demonstrate that the CaWO4∶Eu3+,Tm3+ red phosphors are promising as color converters for application in white light-emitting diodes and display devices.