Effect Of Composition Modulation On The Luminescence Properites Of Eu³⁺and Er³⁺ In The Li_1-xAg_xLn（MoO₄）₂ Phosphors

The scheelite structure molybdates have extremely extensive application in the field of photoelectric materials. The molybdate matrix has the advantages of good structure stability, more adjustable chemical composition, low synthesis temperature, and rich optical performance etc. However, the luminescence efficiency of molybdates is not high, which limits their applications in the field of optical devices. Thus, how to improve the luminous intensity and luminous efficiency of molybdate luminescence materials has become a hot research field. In this paper, Li1-xAgxLn(Mo O4)2 are the research objects, effect of ccomposition modulation on the luminescence poperites of Eu3+and Er3+ has been discussed.The Eu3+and Er3+activated Li1-xAgxLu(Mo O4)2 down/up conversion phosphors were synthesized by the solid state reaction method. In order to better understand the luminescent properties and mechanism of molybdates luminescence material, in this paper, we have taken commonly used research methods such as XRD was used to characterize the phase, the steady state fluorescence spectroscopy and transient fluorescence spectroscopy were used to characterize the luminescence behavior, besides, the Raman spectroscopy was used to characterize the microstructure changes of materials and properties of chemical bonds, and combining with the structural refinement to further determine the phase symmetry. By changing the Li/Ag ratio in the matrix and concentration of activator ion, researching the excitation and emission spectra of the prepared samples under different conditions to optimize down/ up conversion luminescent properties, looking for the best composition of fluorescent powder, and trying to explain the enhancement mechanism of fluorescence spectrum, Finally, through the experimental data and the built models, the crystal structure and down/up conversion luminescence properties were researched and discussed in detail. The main results are concluded as follows:(1) LixAg1-xYb0.99(MoO4)2:0.01Er3+ continuous solid solution upconversion fluorescent materials were selected as research objects, finding that the increase of the content of Li+ can improve the upconversion luminescence intensity of Er3+ in the system. Combining with the ionic deformation caused by material composition modulation, the relationship between the rare earth doped luminescence performance and ionic structure properties evolution was explained.(2) A series of Li1-xAgxLu1-y(Mo O4)2: y Eu3+ red phosphors were synthesized. The increase of the content of Li+ not only can change the luminescence intensity of Eu3+ in a certain doping concentration range, but also can change the relative intensity and position of Mo-O charge transfer state, at the same time, which can affect the relative strength and the position of the excitation peak of f-f transition of the Eu3+(395 nm and 465 nm), and corresponding with the intensity of emission peak.