Synthesis And Luminescence Properties Of M₈MgCe?PO₄?₇:Eu²⁺?M=Ca,Sr?phosphors

(1)Fluorescent converted white light?LED?is the fourth generation solid lighting source.Due to simple production process,environmental friendliness,economy and efficiency,it has become a research hotspot in the field of display lighting.White LED conversion material is the important component to realize white light LED.The research of rare earth ion doped single host phosphors excited by ultraviolet and near ultraviolet light has attracted more and more attention.In this thesis,three kinds of phosphors were prepared by combustion assisted method,and the effects of host structure and energy transfer process on luminescent properties here be systematically studied.?2?In this dissertation,three kinds of phosphates,Ca₈Mg_xZn_1-x-x Ce?PO₄?₇,Ca₈Zn_xCe?PO₄?₇,andSr₈MgCe?PO₄?₇prepared as host.A series of phosphors doped with Eu²⁺,Mn²⁺or Eu²⁺/Mn²⁺have been successfully prepared.The results are as follows:?3?We prepared the new scheelite-type solid solution phosphors of Ca_8-y(Mg_1-xZn_x)Ce?PO₄?₇:yEu²⁺with color tunable luminescence.The energy transfer?ET?fromCe³⁺toEu²⁺process has been verified by the spectral analysis.Moreover,the emitting color can be turned from blue to green in Ca_7.86(Mg_1-xZn_x)Ce?PO₄?₇:0.14Eu²⁺by increasing the Zn²⁺concentration.It is found that the mechanism of tunable luminescence cannot be attributed to crystal field strength or energy transfer.The Zn²⁺ion substitution for Mg²⁺ion causes an increase of the Eu²⁺excitation efficiency.More energy transferred between Ce³⁺and Eu²⁺ions,leading to the tunable luminescence for Ca_7.86(Mg_1-xZn_x)Ce?PO₄?₇:0.14Eu²⁺phosphor..?4?single-composition and color tunable CZCP:Eu²⁺,Mn²⁺phosphors have been synthesized through the combustion-assisted synthesis method.Ce³⁺acts as one of component of host concurrently as activator and sensitizer in Ca₈ZnCe?PO₄?₇.For CZCP:xEu²⁺,the emission color change from violet-blue to green as a result of increasing the Eu²⁺content?x?,while the emission color of CZCP:yMn²⁺phosphors can be tuned from violet-blue to red by energy transfer between Ce³⁺and Mn²⁺.In addition,a wide-range-tunable white light emission can be realized by precisely controlling the contents of Eu²⁺and Mn²⁺ions.?5?A series of Eu²⁺mono-doped and Eu²⁺/Mn²⁺co-doped Sr₈MgCe?PO₄?₇phosphors have been synthesized.The phosphors of SMCP:Eu²⁺exhibited very wide emission band,including Eu1 high-energy emission band with 9coordination and[Eu2 Eu3]low-energy emission band with lower coordina tion.The energy transfer process from Ce³⁺to Eu²⁺/Mn²⁺and Eu²⁺to Mn²⁺ar e existence.CIE coordinate of Phosphor SMCP:0.08Eu²⁺,0.24Mn²⁺is?0.3653,0.3332?,the color temperature is 3977 K,and the luminous quantum efficiency is about 70%.The results indicate that the phosphor SMCP:Eu²⁺,Mn²⁺has good potential application value in near-ultraviolet emission LED.