Synthesis And Luminescent Properties Of Trivalent Rare Earth Ion Activated K₅Y?MoO₄?₄ Phosphors

Some kinds of K₅Y?MoO₄?₄ phosphor doped with trivalent rare-earth ions Eu³⁺,Sm³⁺,Tb³⁺ and Dy³⁺ were prepared via the high temperate solid-stated method in this paper.The microstructure,fluorescent spectrum,chromaticity coordinates and time-resolved spectrum were analyzed and studied.?1?The K₅Y_1-x?MoO₄?₄:xEu³⁺ red phosphors were synthesized,which are suitable for nearly ultraviolet and blue light effective excited.The X-ray diffraction patterns indicated that the sample is a pure phase of K₅Y?MoO₄?₄.The excitation spectrum consists of charge transfer band and a series of peaks in 200-500 nm.The main excitation peaks are located at 395 nm and 469 nm,which are corresponding to the 7F0?5L6 and 7F0?5D2 transition of Eu³⁺.The main emission is located at 623 nm,corresponding to ⁵D₀?⁷F₂ transition.With the increasing of Eu³⁺ the luminescent of phosphors rise gradually.The concentration quenching does not occur in the experimental range.At ⁵D₀ energy,the fluorescence lifetime of Eu³⁺ was about 1.490 ms?2?A series of K₅Y_1-x?MoO₄?₄:xSm³⁺?x=1%,3%,5%,6%,8%,10%,12%?red phosphor was prepared.The excitation spectrum consisted of a series characteristic transition of Sm³⁺.The main excitation is located 409 nm.The emission spectrum of the K₅Y?MoO₄?₄:Sm³⁺ phosphors was composed of some sharp peaks,which centered at 577 nm,614 nm,657 nm,corresponding to the 4G5/2?6HJ/2?J=5,7,9?typical transitions of Sm³⁺,respectively.The strongest one appears at 614 nm.With the increase of Sm³⁺ doping content,the luminous intensity first increases then decreases.The concentration quenching could be observed when the doping concentration of Sm³⁺ ions was more than 6 mol%,and it was confirmed that the mechanism of concentration quenching was electric dipole-dipole interaction.The CIE show that color coordinates of the K₅Y_1-x?MoO₄?₄:xSm³⁺ are located at the red light district.?3?A green phosphor K₅Y?MoO₄?₄:Tb³⁺ was synthesized for white LED.The X-ray diffraction patterns indicated that the sample is a pure phase of K₅Y?MoO₄?₄.It shows five major emission peaks locating at 424 nm?501nm?555 nm?591 nm and 630 nm,which correspond to the ⁵D₃?⁷F₄ and ⁵D₄?7FJ?J=6,5,4,3?typical transition of Tb³⁺,respectively.The main excitation peak locates at 380 nm,which can be excited by UV-LED.It was resedrched that the luminescent intensity of K₅Y?MoO₄?₄ powder changed along with different concentrations of Tb³⁺ ions.At ⁵D₄ energy,the fluorescence lifetime of Tb³⁺ was about 0.253 ms?4?A series of single white light-emitting phosphors of K₅Y?MoO₄?₄:Dy³⁺were synthesized.The spectra of K₅Y?MoO₄?₄:Dy³⁺ shows that the excitation spectra was composed of several peaks at 300⁵00 nm and the main excitation is located 396 nm.Under the excitation peak of 396 nm,it shows strong white rey.The major emission peaks locate at 496 nm 588nm and 680 nm,which correspond to the 4F9/2?6HJ/2?J=15,13,11?typical transition of Dy³⁺,respectively.At 588 nm,sample have the strongest peak,where Dy³⁺ in low symmetry.It belongs to the electric dipole transition of Dy³⁺.It have the largest luminescent intensity when Dy³⁺ in K₅Y?MoO₄?₄:Dy³⁺ x?Dy?=0.11%.The mechanism of concentration quenching was electric dipole-dipole interaction.Color coordinates of the samples under different Dy³⁺ concentrations were all in the white light category.