Study On The Structure And Properties Of Ion-doped Yttrium Aluminum Garnet Phosphors

White LED has become a new generation of green solid-state lighting source because of its small size,high efficiency,long life and many other advantages.Recently,the mainstream solution for white LEDs is the mainstream solution for white LEDs is to use blue chips with YAG:Ce³⁺yellow phosphors.However,due to the lack of red light components in the emission spectrum of YAG:Ce³⁺yellow phosphors,the color rendering index of the device is low and the color temperature is high.In recent years,the research on improving YAG:Ce³⁺phosphors is very active,which is a hot issue in phosphor researches.Based on the structure of YAG:Ce³⁺,this paper designs single-site,double-site and multi-site substitution.The influence of various ion substitutions on the sample structure,luminescence performance and thermal stability is systematically studied.The performance of YAG:Ce³⁺phosphor is improved,which lays a foundation for the development of white LED phosphors with excellent performance.The main research contents and results of the thesis are as follows:1.By Ga³⁺?Al³⁺,In³⁺?Al³⁺,Gd³⁺?Y³⁺single site substitution,a series of Y2.94Al5-x Gax O12:0.06Ce³⁺,Y2.94Al5-x Inx O12:0.06Ce³⁺,Y2.94-x Gdx Al5O12:0.06Ce³⁺phosphors are prepared.The effects of single site substitution of Ga³⁺?Al³⁺,In³⁺?Al³⁺,Gd³⁺?Y³⁺on the crystal structure,luminescent properties and thermal stability of the samples are systematically studied,as well as the change of spectral wavelength and the mechanism of thermal stability are discussed in detail.The results show that both the luminescent intensity and thermal stability decrease while the spectral regulation is realized.2.By non-equivalent co-substitution of Lu³⁺-Ga³⁺?Y³⁺-Al³⁺,La³⁺-Ga³⁺?Y³⁺-Al³⁺,Si⁴⁺-Ga³⁺?Al³⁺-Al³⁺,a series of Y_2.94-xLu_xAl₄Ga O:0.06Ce³⁺,Y_2.94-xLa_xAl₄Ga O₁₂:0.06Ce³⁺,Y_2.94Al_4-xSi_xGa O₁₂:0.06Ce³⁺phosphors are prepared.The effects of Lu³⁺,La³⁺,Si⁴⁺substitution on the crystal structure,luminescence performance and thermal stability of YAGG:Ce³⁺have been studied in detail,as well as the spectral wavelength change and thermal stability mechanism are explored in depth.The results show that the co-substitution of Lu³⁺-Ga³⁺improves the luminous efficiency of the sample,the emission spectrum is blue-shifted,and the emission loss in the cyan region is reduced.The emission from the yellow-green to the green region can be tunable,and the sample has excellent thermal stability.Pc-LEDs made of Y2.94-x Lux Al4Ga O12 have high luminous efficiency and color rendering index.When x=2.5,the color rendering index reaches 88.9 and the luminous efficiency reaches 90lm/W,indicating that this is an excellent warm white LED Green phosphor.The emission spectra of Y2.94-x Lax Al4Ga O12:0.06Ce³⁺phosphors show a red shift from506nm to 516nm with the increase of x from 0 to 0.3,and the emission intensity increases.The emission spectra of Y2.94Al4-x Six O12:0.06Ce³⁺phosphors show blue shift and thermal stability.The Pc-LEDs made of the phosphors have a high color rendering index,and when x=0.15,the color rendering index reaches 88.9.3.By using non-equivalent multi-site substitution of La³⁺-Ga³⁺-Si⁴⁺?Y³⁺-Al³⁺-Al³⁺,Gd³⁺-Mg²⁺-Si⁴⁺?Y³⁺-Al³⁺-Al³⁺,Gd³⁺-Si⁴⁺-N^3-?Y³⁺-Al³⁺-O^2-,a series of Y2.94-x Lax Al3.85Si0.15Ga O12:0.06Ce³⁺,Y1.94Gd Al5-2x Mgx Six O12:0.06Ce³⁺,Y1.94Gd Al5-x Six Nx O12-x:0.06Ce³⁺phosphors are prepared.The crystal structure,luminescence performance and thermal stability of each series of phosphors have been systematically studied,and the spectral wavelength change,thermal quenching and afterglow mechanism have also been researched.The emission spectrum of Y2.94-x Lax Al3.85Si0.15Ga O12:0.06Ce³⁺phosphor is red shifted.With the change of x from 0 to0.2,the emission of the sample is adjustable from green to yellow green,and the emission intensity is enhanced,and the quantum efficiency is improved.At the same time,the sample shows excellent thermal stability.The Pc-LEDs made of the phosphor have a high color rendering index.When x=0.1,the color rendering index is 87,but the color temperature is improved.Constructing a rigid local structure model of the matrix explains the light and color properties of the sample and the corresponding relationship between the thermal stability and the rigidity of the matrix structure.The emission spectrum of Y1.94Gd Al5-2x Mgx Six O12:0.06Ce³⁺series phosphors increases from x=0 to 2 and the emission peak shifts red from 547nm to 570nm,and the half-width of the emission spectrum increases from 67nm to 77nm,indicating that it can be used in white light.It shows that it can produce high color rendering effect in white light application,and it is the preferred object of a class of excellent quality orange phosphors.4.The long afterglow luminescence phenomenon of La³⁺and Si⁴⁺doped YAGG:Ce³⁺series phosphors is observed.Taking Y2.94Al3.55Si0.45Ga O12:0.06Ce³⁺as an example,the trap energy level is 0.4799e V and The afterglow time is as long as 120s.The long afterglow luminescence mechanism of Si⁴⁺doped YAG:Ce³⁺phosphors is discussed,and the potential application value of long afterglow phosphors in the field of optical storage is revealed.