摘要
本文报导了Dy^(3+),Sm^(3+)和Ce^(3+)离子在M_3La_2(BO_3)_4(M=Ca,Sr,Ba)基质中的激发与发射光谱;研究了Dy^(3+)离子黄蓝发射的相强度随基质化合物的组成和结构的不同而呈现的变化规律;讨论了Sm^(3+)离子电荷迁移激发带的能量与基质中近邻阳离子的关系并分析了Sm^(3+)和Eu^(3+)离子4f电子构型对电荷迁移带能量的影响。本文还给出了Dy^(3+),Sm^(3+)和Ce^(3+)离子发光的浓度淬灭值。
In this paper, the luminescence properties of Dy3+, Sm3+ and Ce3+ in M3La2(BO3)<(M=Ca, Sr, Ba) are reported.M3La2(BO3)4(M = Ca, Sr, Ba) are the compounds with orthorhombic structure. The site symmetry of RE3 + (RE = Dy, Sm, Ce) is lower in Ca3La2 (BO3)4 than that in Sr and Ba compounds .We observe that the energy levels of RE3 ±ions are much more split in Ca matrix.This is well corresponding with the relationship between the splitting of energy levels and site symmetry.The ratio, R = I4F9/2-66H13/2/I4F9/2-6H15/2,of Dy3+emission is decreasing with the change of M2+ from Ca2 + to Ba2+. According to Table 1, the blue emission of Dy3 + is more intense than its yellow one in Ca matrix.Notice that, although the site symmetiy of Dy3+ in Sr and Ba matrices is the same, the R are different. This shows that the ratio of yellow to blue emission of Dy3 + is not only affected by the site symmetry, but also by the composition of the compounds.The charge transfer bands of Sm3+ move to longer wavelength with the change of M2 + (from Ca2+ to Ba2+). This phenomenon has been observed and discussed for Eu3 + in the same matrices. The 4f electron configurations of Sm3+, and Eu3+ arc 4f5 and 4f6 respectively. When get an electron from coordination anion, Eu3+ will become 4f7 state(half-filled), which is more stable than the 4f6 state for Sm3 + . Therefore, the energy of charge transfer band of Sm3+ is higher than that of Eu3+ in the same condition. Table 2 makes a comparison.The d-f emission bands of Ce3+ peak at 436 nm in Ca matrix and 424 nm in Sr and Ba compounds respectively.In Sr3La2(1-x)(BO3)4 : RE2x3+ ( RE = Dy, Sm, Ce ), the concentration quenching of Dy3+ and Sm3+ luminescence starts at x=0.02 and x = 0.04 respectively; Ce3+ has higher quenching concentration, no large quenching is observed when x amounts to 0.3.
出处
《发光学报》
EI
CAS
CSCD
北大核心
1989年第3期213-218,共6页
Chinese Journal of Luminescence
