Research On Luminescence Properties Of Rare Earth-Activated La₂CaB₈O₁₆Phosphors

White LEDs have occupied half of the lighting market,because of their long lifetime,energy conservation and small size.Combination of phosphors and LED chips is the main trend for generating white light,which includes two types of blue light and near UV excitation.For the first route,there are some problems of poor color rendering index and high color temperature due to lack of red light.It is difficult for the second to control purity and ratio of tricolor phosphor for emitting red,green or blue light.This means it is very necessary to develop a tricolor or white phosphor with excellent luminescence properties.This thesis concentrates on the luminescence properties of rare earth ions doped La₂CaB₈O₁₆.The details are as follows:1)La_1.95Eu_0.05MB₈O₁₆?M=Ba,Sr?were synthesized by solid state reaction method,and their luminescence properties were studied.The results suggest that the crystal structure is not changed significantly by the Sr²⁺substitution for Ca²⁺in LCB8.While for the Ba²⁺substitution of 40 mol%,there appears one new phase LaBaB₉O₁₆.The emission intensity of samples reach the maximum for Ba²⁺content of 100 mol%and Sr²⁺content of 40 mol%.In addition,La_1-x-x Eu_xBaB₉O₁₆6 samples were synthesized by sol-gel method and their luminescent properties were also investigated.2)La_1.90CaB₈O₁₆:0.05Eu³⁺,0.05Re³⁺?Re=Bi,Tb,Sm,Dy?were prepared by solid state reaction method and their luminescence properties were discussed.The results indicate that the emission intensity of Eu³⁺co-doped with Bi³⁺,Tb³⁺,Sm³⁺or Dy³⁺respectively has been improved to some extent.3)La_2-x-y-x-y Tb_xCe_yCaB₈O₁₆6 samples were prepared by solid state method,and their luminescent properties were analyzed.The results show that the green emission of Tb³⁺is enhanced with the addition of Ce³⁺,which transfers energy to Tb³⁺.4)La_2-x-x CaB₈O₁₆:xDy³⁺phosphors were prepared by solid state method,and their luminescence properties were studied.The results reveal that Dy³⁺with different doping concentration in LCB8 exhibits a good white light emission.