Luminescence Properties Of Rare Earth Ions Doped Lanthanum Strontium Silicate Phosphors

As new green lighting sources,LED lights have extensively applications.The developing of commercial LEDs is limited by its components including the phosphors.The phosphor with high performance and high thermal stability is the key to improve LED lighting.In this thesis,the silicate phosphors with good thermal stability was prepared and its luminescence properties are studied systematically.There are five chapters.The first chapter introduces the basic structure of LED,the factors affecting luminescence,matrix materials and rare earths commonly.The second chapter introduces experimental drugs,equipment,characterization methods.The third chapter is the experimental exploration is the study on Sr₃Gd₂（Si₃O₉）₂:Eu.The exploration work in the early stage mainly including to find the appropriate host,the best sintering temperature and the appropriate reducing atmosphere.The fourth chapter is the study on Sr₃Lu₂（Si₃O₉）₂:Eu²⁺.The crystal structure of silicate Sr₃Lu₂（Si₃O₉）₂,the luminescence properties of Eu²⁺ions at different concentrations,the intensities with different temperatures and the fluorescence lifetimes of rare earth ions were analyzed systematically.Chapter five is the conclusions to summarize the full text.Firstly,we got the host and experimental conditions.Then,Sr₃Lu₂（Si₃O₉）₂:Eu²⁺was chosen to study deeply.The energy dispersion effect of Eu²⁺ions was investigated and the physical mechanism was discussed by using Blass’s theory.The results in detail are as follows:1)Based on the literatures and the experimental exploration,Sr₃Lu₂（Si₃O₉）₂:Eu²⁺was chosen to be the host.2)Sr₃Lu₂（Si₃O₉）₂:Eu²⁺was prepared and the luminescence properties are investigated.On the basis of the crystal structure and the lifetimes,it is confirmed that Eu²⁺occupies three different luminescent centers in Sr₃Lu₂（Si₃O₉）₂.3)The intensities changed with the concentration of Eu²⁺was studied.It was explained in details that the FWHM becomes larger and the luminescence peak is red-shifted;the intensity of the emission spectrum first increases and then decreases,as the concentration of Eu²⁺ions increases.4)The colorimetric coordinates of the sample was calculated.