基于双发光位点能量传递构建高效窄带钙钛矿构型K_(2)BaPO_(4)F:Eu^(2+)荧光粉

Efficiently Narrow-band Perovskite-type Phosphor K_(2)BaPO_(4)F∶Eu^(2+)Based on Dual-sites-triggered Energy Transfer Behavior

随着近紫外芯片激发三基色荧光粉技术的发展,开发用于液晶显示背光源以满足高品质显示需求的新型窄带蓝色荧光粉已经成为材料研究者日益关注的焦点。本文采用高温固相法合成了具有钙钛矿结构原型的K_(2)BaPO_(4)F∶Eu^(2+)窄带蓝色荧光粉。K_(2)BaPO_(4)F基质由[FK_(4)Ba_(2)]八面体以共享Ba、K原子的方式相连形成三维网状阴离子框架,进而与孔道中的[PO_4]四面体连接形成K_(2)BaPO_(4)F钙钛矿结构框架。Rietveld精修分析表明,Eu^(2+)同时占据Ba^(2+)和K^(+)位点形成[Eu(1)O_8F_(2)]和[Eu(2)O_(6)F_(2)]配位多面体,两种多面体发光中心存在由偶极-偶极效应引起的Eu(1)→Eu(2)能量传递过程,使荧光粉具有发射峰值波长为432nm、半峰宽为43nm的高亮度窄带蓝光发射。基于密度泛函理论的第一性原理计算表明,K_(2)BaPO_(4)F基质为间接带隙化合物,理论带隙值为5.035eV。K_(2)BaPO_(4)F∶Eu^(2+)荧光粉展现了合适的荧光热稳定性(I_(493K)/I_(293K)=64%)和较高的内、外量子效率(分别为72.8%和46.4%),其性能指标虽然劣于BaMgAl_(10)O_(17)∶Eu^(2+)、K_(1.6)Al_(11)O_(17+δ)∶Eu^(2+)、Na_(3)Sc_(2)(PO_4)_(3)∶Eu^(2+)等典型蓝粉,但优于其他一些已报道的蓝色荧光粉。上述研究工作不仅展现了K_(2)BaPO_(4)F∶Eu^(2+)作为一种新型窄带蓝色荧光粉的应用潜力,而且也为基于矿物结构原型策略探索新型荧光粉提供了可能性。

Along with the development of versatile trichromatic phosphors,exploring novel narrow-band blue-emit-ting phosphors has been an ongoing focus in liquid crystal display backlighting to satisfy the high-quality display de-mands.Herein,an intriguing narrow-band blue-emitting phosphor K_(2)BaPO_(4)F∶Eu^(2+)belonging to the perovskite-type structural prototype is synthesized via the solid-state reaction.Structural analysis indicates that the[FK_(4)Ba_(2)]octahe-dra is interlinked with each other by sharing Ba and K atoms to build a three-dimensional network together with[PO4]tetrahedra in the cavities.Rietveld refinement analysis shows that the Eu^(2+)ions reside in both Ba^(2+)and K^(+)sites to form the[Eu(1)O8F_(2)]and[Eu(2)O_(6)F_(2)]polyhedra,which totally induce an intense blue emission peaking at 432 nm with a narrow full width at half-maximum of 43 nm,theoretically verified by the dipole-dipole interaction in the Eu(1)→Eu(2)energy transfer process.The electronic structure of K_(2)BaPO_(4)F matrix is studied by the first-prin-ciple calculation on the basis of the density functional theory,demonstrating that it has a large indirect band of 5.035 eV.The K_(2)BaPO_(4)F∶Eu^(2+)phosphor exhibits a suitable thermal stability(I493 K/I293 K=64%)and possesses the satisfac-tory internal/external quantum efficiency of 72.8%/46.4%,which although is inferior to that of the representative BaMgAl10O17∶Eu^(2+),K1.6Al11O17+δ∶Eu^(2+)and Na_(3)Sc_(2)(PO4)_(3)∶Eu^(2+)phosphors,yet surpasses some other recently reported blue-emitting phosphors.Consequently,the present work not only demonstrates the potential of K_(2)BaPO_(4)F∶Eu^(2+)phosphor as a new narrow-band blue-emitting phosphor candidate,but provides the possibility for exploring the novel phosphors inspired by the mineral-type structural prototypes.