Synthesis And Performance-Tuning Of Two Kinds Of Ce³⁺-Doped Garnet Luminescence Materials

White Light-Emitting Diode（w-LED for short）has attracted wide attention in the lighting field because of its advantages such as high efficiency,energy saving,long service life,small size and environmental friendliness.The mainstream commercial implementation of w-LED is to combine light-emitting diodes with phosphors.There are two main ways to realize this kind of phosphor-converted LED.One method is to combine blue light chips with yellow phosphors to achieve white light.However,the white light obtained by this method has the problem of missing part of red and green light,leading to high Correlated Color Temperature（CCT）and poor Color Rendering Index（CRI）.Another method is to use near-ultraviolet chips with blue,green and red phosphors to obtain the w-LED,its CRI is good,but there is a reabsorption effect and the luminous efficiency is reduced.Phosphors are the key to the performance of w-LED.The development and design of efficient and stable phosphors and the study of tuning mechanism are of great significance.In this work,the garnet system doped with Ce³⁺was selected as the research object.A series of cyan phosphors and yellow-green phosphors were designed and synthesized by using single substitution and chemical unit co-substitution strategies.The spectral performance tuning mechanism was explored,hoping to provide reference ideas for the development and performance optimization of phosphors.The main research contents and results are as follows:（1）Taking cyan phosphor Ca₂YHf₂Al₃O₁₂:Ce³⁺as the initial research object,single substitution strategy was carried out for the cation at sites of dodecahedron,octahedron and tetrahedron,respectively and the Ce³⁺-doped Ca₂(Y_1-x,Lu_x)Hf₂Al₃O₁₂（0≤x≤1）,Ca₂(Y_1-x,Gd_x)Hf₂Al₃O₁₂（0≤x≤1）,Ca₂Y(Hf_1-x,Zr_x)₂Al₃O₁₂（0≤x≤1）,Ca₂YHf₂(Al_1-x,Ga_x)₃O₁₂（0≤x≤1）solid solution phosphors were obtained.The effects of cation substitution at different sites on crystal structure and spectral performance were analyzed.There were differences in the effect of cation substitution in different sites on spectral performance:cation substitution in the dodecahedral sites had a significant effect on the spectrum,while cation substitution in octahedral and tetrahedral sites had less effect on the spectrum.The w-LED device was fabricated based on the cyan phosphor and the photoelectric performance was studied.（2）Taking Ca_1.5Y_1.5Al_3.5Si_1.5O₁₂:Ce³⁺as the initial research object,and the Ce³⁺-doped Ca_1.5-xY_1.5+xAl_3.5+xSi_1.5-xO₁₂（0≤x≤0.5）yellow-green solid solution phosphors were obtained by the chemical unit co-substitution strategy of the substitution of[Y³⁺-Al³⁺]for[Ca²⁺-Si⁴⁺]ion pairs.The effect of solid solution substitution on crystal structure and luminescence performance was investigated,and the internal mechanism of spectral redshift and luminescence intensity enhancement was discussed.The substitution of[Y³⁺-Al³⁺]ion pair for[Ca²⁺-Si⁴⁺]led to greater distortion degree of the dodecahedron at luminescence center and the enhancement of crystal field splitting,resulting in the emission spectrum redshift.In the process of chemical unit co-substitution,the reduction degree of Ce⁴⁺increased,leading to the increase of the effective concentration of the luminescence center,which leads to the enhancement of luminescence.The w-LED device was fabricated based on the yellow-green phosphor and the photoelectric performance was studied.