Ce^(3+)在Na_2Ca_(1-x)SiO_4:xCe^(3+)中的发光特性及晶体学格位  

Luminescence Characteristics and Crystallographic Sites of Ce^(3+) in Na_2Ca_(1-x)SiO_4:xCe^(3+)

作　　者：杨志平[1] 宋延春[1] 赵青[1] 韩月[1] 潘飞[2] 

机构地区：[1]河北大学物理科学与技术学院 [2]河北大学电子信息工程学院,河北保定071002

出　　处：《硅酸盐学报》2012年第9期1346-1350,共5页Journal of The Chinese Ceramic Society

基　　金：国家自然科学基金项目(50902042);河北省自然科学基金(F2009000217)资助项目

摘　　要：采用高温固相法合成了Na2Ca1-xSiO4:xCe3+蓝色发光材料,并对其发光特性进行了研究。测得激发光谱为双峰宽谱,峰值分别位于279nm和360 nm,属于Ce3+的4f-5d跃迁,可被紫外-近紫外LED芯片有效激发。样品的发射光谱为不对称单峰宽谱,主峰位于439nm。利用van Uitert公式证明了Ca在Na2CaSiO4中只存在一种晶体学格位,判定经Gauss分峰拟合后的425 nm与460 nm子发射峰均来自于八配位Ce3+的发射,非对称发射的原因是局部晶体场的不对称和Ce3+能级劈裂。研究了Ce3+掺杂量对Na2Ca1-xSiO4:xCe3+材料发光特性的影响。结果显示,随Ce3+掺杂量的增大,发光强度先增大后减小,且发射光谱红移。Ce3+掺杂量为4%(摩尔分数)时,出现浓度猝灭,根据Dexter理论分析猝灭机理为电偶极-电四极相互作用。A blue phosphor of Na2Ca1-xSiO4：xCe3＋ was prepared by a solid-state method at high temperature. The luminescence char- acteristics of the prepared sample were investigated. The sample appears one asymmetrical emission band at 439 nm, which can be divided into two bands by the Gaussian fitting. The excitation spectrum has two broad bands at 279 nm and 360 nm, belonging to 4f-5d transitions of Ce3＋. The crystallographic sites of Ca2＋ in Na2CaSiO4 were analyzed. There exists only one Ca site in Na2CaSiO4 crystal, which can be calculated by the van Uitert formula. Therefore, the divided emission bands located at 425 nm and 460 nm both originate from the Ce3＋ center of the eight coordinate. The dissymmetrical emission band of Na2CaSiO4：Ce3＋ phosphor is caused by asymmetry of the local crystal field and Ce3＋ ion energy level splitting. The effect of Ce3＋ concentration on the luminescent intensity of Na2Ca1-xSiO4：xCe3＋ phosphor was investigated. The result shows that the luminescent intensity first increases and then decreases with increasing of Ce3＋ concentration, and reaches the maximal value at 4% in mole. The concentration quenching mechanism is due to the electric dipole-electric quadrupole interaction from the Dexter theory.

关 键 词：发光 硅酸钙钠 晶体学格位 荧光粉 

分 类 号：O482.31[理学—固体物理]