碱金属离子对SrCl2：Eu^2＋发光性能的影响

采用中低热固相法合成SrCl_2:Eu~(2 ),R~ (R=Li,Na,K)荧光体,用XRD,PL,XPS等方法研究了它的结构、荧光性质以及铕的价态.结果表明,SrCl_2:Eu~(2 ),R~ 荧光体在262nm或330 nm波长的UV光激发下产生强蓝光,发射峰位在405～415 nm之间.因为Eu~(2 )和Sr~(2 )的离子半径相近,还原生成的Eu~2 )占据部分Sr~(2 )的格位,有利于晶格的稳定,不会导致晶格畸变.而且在六方晶系中,Cl~-离子提供了一个SrCl 2:Eu~(2 )稳定存在的环境,Eu~(3 )→Eu~(2 )的还原可以通过不等价取代实现.掺杂Na~ 和K~ 荧光体发光强度增加相近的原因是Na~ 和K~ 与Eu~(2 )的半径之差接近,且与Sr~(2 )的半径相近,掺入后可以向Eu~(3 )提供格位.K~ 离子的半径大于Eu~(2 ),致使基质晶场强度明显增大,发射峰位明显红移.

The Effect of Alkali Metal Ions on the Photoluminescence Properties of SrCl2: Eu2+ Phosphors

Eu and alkali metal ions co-doped SrCl2 : Eu2 ,R (R = Li,Na. K) phosphor was prepared by solid state reaction at moderate, lower-heating temperature. Its structure, photoluminscent properities and valent state of Eu ion were characterized by XRD, PL, XPS respectively. The results revealed that under excitation of 262 nm or 330 nm ultraviolet light, this phosphor emits strong blue fluorescence, with emission peak at the range from 405 nm to 416 nm. The co-doping of alkali metal ion may act as diluting ion for the activator. On the other hand, this co-doping enhanced the crystal field and covalency, which resulted in the increasing of emission intensity of SrCl2 : Eu2 ,R . The reduction mechanism of Eu3 to Eu2 in SrCl2 matrix, which may be due to the unequivalent substitution of Eu3 for Sra , is also discussed.