Investigation On The Luminescence Properties Of Fluorosilicate Phosphors For White Light Emitting Diodes

This thesis investigated the luminescence properties of fluorosilicate phosphors such as F-doped Sr1.7Mg0.3SiO4based phosphors, Ca2LiSiO4F based phosphors and Ca2NaSiO4F based phosphors which were doped with different rare earth ions.For Eu2+and Mn2+singly-doped Sri.7Mg0.3SiO4phosphors and Eu2+and Mn2+codoped Sri.7Mg0.3SiO4phosphors, their luminescence properties have been studied in detail. Eu2+singly doped Sr1.7Mg0.3SiO4phosphor gives455and550nm emissions, and their intensities change with increasing Eu2+concentrations. Eu2+and Mn2+co-doped phosphors present455、550and670nm emission bands, the intensities change with Mn2+concentrations, and the phosphors could emit white light under UV light. In addition, F-doped Sr1.7Mg0.3SiO4Eu2+, Mn2+could emit high quality white light under UV light (380nm).The structures and luminescence properties of different rare earth ions (Eu2+, Ce3+, Tb3+, Dy3+, Eu3+, Sm3+) doped Ca2LiSiO4F phosphors were investigated. Different rare earth ions have little influence on Ca2LiSiO4F phosphors’structure. And the host lattices are agreement with Ca2LiSi04F (JCPDS28-0558), while a small amount of lattice can be indexed to the phase Ca4Si2O7F2(JCPDS41-1474). Different rare earth ions doped phosphors emit different colors, such as, Eu2+emits white light, Ce3+emits blue light, Tb3+emits green-yellow light, Dy3+emits white light as well, Eu3+and Sm3+emit red light which can be used as UV-NUV light excitation white light emitting phosphor.The structures and luminescence properties of different rare earth ions (Eu2+, Ce3+, Dy3+, Eu3+, Sm3+) doped Ca2NaSiO4F phosphors were investigated. The structure of low concentration rare earth ions doped Ca2NaSiO4F phosphors are agreement with Ca2NaSiO4F (JCPDS27-1228), while a small amount of other phases exist. However, when rare earth ions concentration increased, the structure of Ca2NaSiO4F phosphors changed because the rare earth ions were into the internal lattice by substituting Ca2+. And, different rare earth ions doped phosphor can emit different colors, such as, Eu2+emits white light, Ce3+emits blue light, Dy3+emits white light as well, Eu3+and Sm3+emit red light which can be used as UV-NUV light excitation white light emitting phosphor as well.