Luminescence Properties Of Rare Earth Doped Glass Ceramics Containing LiYF₄ Nanocrystals For Light-emitting Diodes

In recent years,rare earth ions doped glass-ceramic has become one of the most popular research trends in the fields of LED display.Oxyfluoride glass-ceramics stand out from a wide range of matrix materials,this is due to the fact that oxyfluoride glass ceramics is a new type glass ceramic which is composed by fluoride crystallites embedded in an oxide glass matrix.Oxyfluoride glass-ceramics provide a lower phonon energy crystal field environment for rare earth ions,achieving a higher fluorescence rate.The main contents of this paper is to study the rare earth ions(Pr³⁺,Dy³⁺and Eu³⁺)single doped LiYF₄ glass-ceramic material.We have analyzed the spectral characteristics of Pr³⁺,Dy³⁺and Eu³⁺ions doped with LiYF₄ glass-ceramic,the corresponding excitation spectra?emission spectra and the fluorescence lifetime at different thermal treatment temperatures,and its application in white LEDs was discussed.Pr³⁺?Dy³⁺and Eu³⁺activated 43SiO₂-23Al₂O₃-27LiF-17YF₃?mol%?glass were synthesized by a conventional melting technique,rare earth Pr³⁺,Dy³⁺and Eu³⁺ions were added in the form of oxides Pr₂O₃,Eu₂O₃ and fluoride DyF₃,respectively.The glass ceramic was obtained by thermal treatment of the glass sample at different temperatures,respectively.X-ray diffraction and transmission electron microscope were used to monitor the crystalline phase structure after the precursor glasses were annealed,The UV-visible spectra confirmed that the transmittance of glass-ceramics after heat treatment remained about 80%.The spectral properties and lifetime of glass and glass ceramics were investigated.The color coordinates of glass and glass ceramics also be calculated.After the glass-ceramics which doped with Pr³⁺ions was made into LED,the photoelectric and parameters of LED were tested.The results show that the color coordinates of glass-ceramics which doped with Pr³⁺and Dy³⁺ion both located in the white light coordinate region,the photoelectric and parameters of the glass-ceramics which doped with Pr³⁺ion are close to the commercial white LED standard.The glass ceramic which doped with Dy³⁺ion was found to emit white cold light.After the spectra and color coordinates of glass-ceramics which doped with Eu³⁺ion was tested,it was found that the samples emitted red light.We also found that the spectra of Eu³⁺and Dy³⁺ions overlap partially.It shows that Eu³⁺ion is a potential material for warming the white light emitted by Dy³⁺ion.