| White LED is a new solid state lighting source and known as the fourth generation of lighting source for its longer lifetime, non-toxicity and non-pollution, and so on. For fabricating white LED, the single host white emitting phosphor which can be excited by UV LED chips is more suitable than the trichromatic phosphors, in which the light emitted by one phosphor could be resorbed by other phosphors and inadequate color matching exits. The alkaline earth chlorosilicate phosphor formed by the combination of alkaline earth chloride and alkaline earth silicate is one of the most typical single host white emitting phosphors and has caused great concern for its superior optical properties. In this thesis, the following research works started with the synthesis of the phosphors excited by UV LED lamp and aimed at preparing a single host white emitting alkaline earth chlorosilicate phosphor.Some monochrome phosphors for white LED, Ca6Sr4(Si2O7)Cl2:Ce3+(blue phosphor), Ca6Sr4(Si2O7)3Cl2:Sm3+(red phosphor) and Ca6Sr4(Si2CO7)Cl2:Tb3+(green phosphor), were synthesized by high-temperature solid-phase reactions. Their morphologies and structures were analyzed, the effect of the Ce3+, Sm3+, Tb3+ion concentrations on the luminescent properties of the phosphors discussed, and their color coordinates studied.By doping two kinds of rare earth ions, the alkaline earth chlorosilicate phosphors, Ca6Sr4(Si2O7)3Cl2:Ce3+,Sm3+(bluish white) and Ca6Sr4(Si2O7)3Cl2:Eu2+,Sm3+(orangish-green) and Ca6Sr4(Si2O7)3Cl2:Ce3+, Tb3+(the color can be regulated in the range of blue-near white), were prepared. Two single host white emitting chlorosilicate phosphors which can be effectively excited by the near UV LED, Ca6Sr4(Si2O7)3Cl2:Ce3+, Eu2+, Sm3+and Ca6Sr4(Si2O7)Cl2:Ce3+, Tb3+, Sm3+, were synthesized when three kinds of rare earth ions were doped. Their luminescence properties and the optimum doping concentration were studied, and the energy transfer process between rare earth ions were also analyzed. |
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