采用高温固相法合成了Ca4Y6Si6O25:Eu^2+绿色荧光材料。通过X射线衍射分析得知,Ca4Y6Si6O25属于六方晶系,具有P63/m(176)空间点群结构。测定了Eu^2+的激发光谱和发射光谱。Ca4Y6Si6O25:Eu^2+的激发光谱为350~450nm的宽带谱,这与近紫外光LED芯片相匹配。发射光谱是峰值为527nm的不对称宽带发射,这是因为Eu^2+占据了晶格中Ca^2+的位置,并产生了两种不同的发光中心。研究了Eu^2+的含量对Ca4(1-x)Y6Si6O25:4xEu^2+发光性能的影响,随着Eu2+浓度的增大,材料的发光强度先增强后减弱,Eu2+的最佳掺杂摩尔分数为20%(x=0.05)。根据Dexter理论得出,浓度猝灭机理为电四极-电四极相互作用。
Ca4Y6Si6O25∶Eu2+ green phosphor was prepared by high temperature solid-state reaction.The XRD speetrum indicates that Ca4Y6Si6O25 has a hexagonal crystal structure with a space group of P63/m(176).The excitation and emission spectra of Ca4Y6Si6O25∶Eu2+ were measured when the mole fraction of Eu2+ was 20%.Its excitation spectrum is a broad band,from 350 nm to 450 nm,which matches with near ultraviolet LED chip.The emission spectrum of Ca4Y6Si6O25∶Eu2+ exhibits an asymmetry broad band with the peak center at 527 nm,and it is because that Eu2+ takes the place of Ca2+ and forms two different luminescence centers.The effect of Eu2+ concentration on Ca4(1-x)Y6Si6O25∶4xEu2+ intensity was also investigated.With the increase of Eu2+ concentration,the luminescence intensity of the green phosphor get to maximum and then decrease.The optimal mole fraction of Eu2+ is 20%(x=0.05).According to Dexter theory,concentration quenching can be attributed to quadrupole-quadrupole interaction