【摘要】 采用高温固相法合成Sr4-xCaxSi3O8Cl4:Eu2+荧光材料,利用Van Uitert公式讨论Sr4-xCaxSi3O8Cl4:Eu2+中yEu2+的晶格环境和发光特性,确定晶体中有蓝色和黄绿色两种发光中心,并讨论了它们与光谱结构的对应关系。当0<x<0.5,Ca2+固溶入Sr4Si3O8Cl4基质晶格,Eu2+占据八配位Sr2+格位,晶体主要产生蓝色中心的蓝绿色发射;当0.5<x<2,较大的Ca2+掺杂使晶胞参数变小,晶格中的杂质束缚激子态的束缚增强,Eu2+处于杂质束缚激子中心所形成的激发态能量进一步降低,发射位于长波段方向并具有较大的Stokes位移,Sr4-xCaxSi3O8Cl4:yEu2+主要产生黄绿色中心的黄绿色发射光。更多还原

【Abstract】 Alkali earth chlorosilicate of the type Sr_4-xCa_xSi₃O₈Cl₄ was synthesized through the high temperature solid state method.According to the Van Uitert experimental equation,luminescence properties and crystal-lattice environment of Eu²⁺ in Sr_4-xCa_xSi₃O₈Cl₄ crystal were discussed.The possibilities of two Eu²⁺ emission centers,viz.blue and greenish-yellow centers,were found and their corresponding relationships with spectra were also discussed.When the doping amount of calcium（x） varied between 0 and 0.5,Ca²⁺ ions were embedded in the host lattice of Sr₄Si₃O₈Cl₄,and the luminescence of blue center,which was ascribed to the emission of Eu²⁺ that substituted the octa-coordination Sr²⁺ sites,dominated and showed blue-green luminescence.Sr_4-xCa_xSi₃O₈Cl₄:yEu²⁺ exhibited greenish-yellow luminescence when the range of x was between 0.5 and 2.This was due to the fact that the Eu²⁺ emission originated from the formation of an impurity-trapped exciton state.Greenish-yellow emission center was located in the impurity-trapped exciton state which was the lowest excited state of this system,and the Eu²⁺ emission was at long wavelengths,and a large Stokes shift was observed.更多还原