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KCdF3晶体中Cr3+-Li+中心局域结构研究
引用本文:杨子元 屈绍波 等. KCdF3晶体中Cr3+-Li+中心局域结构研究[J]. 发光学报, 2001, 22(1): 12-15
作者姓名:杨子元 屈绍波 等
作者单位:1. 宝鸡文理学院应用物理研究所, 陕西宝鸡721007;2. 西安空军工程学院基础部, 陕西西安710038
基金项目:陕西省教育厅自然科学研究计
摘    要:利用零场分裂参量与晶体结构之间的定量关系,研究了双掺杂晶体KCdF3:Cr3+,Li+的局域结构。指出,对于KCdF3:Cr3+,Li+晶体,四角晶场的形成包含两个方面:(1)由于电荷补偿而产生的等效电荷形成的四角对称晶场;(2)Cr3+的局域结构发生晶格畸变而产生的四角对称晶场。事实上,当Cr3+和Li+掺入KCdF3晶体时,Cr3+代替了Cd2+离子;由于Cr3+离子与Cd2+离子的半径不同、电荷不同、质量不同,导致Cr3+的局域结构发生晶格畸变,由此而产生四角对称晶场;由于电荷补偿,Li+离子取代了[001]方向与Cr3+离子邻近的Cd2+离子,由此产生的等效电荷而形成的四角晶场。这样,Cr3+的局域结构由Oh对称变为C4v点对称。文中建立了ZFS参量和晶体结构之间的定量关系。在考虑晶格畸变和等效电荷的基础上,研究了KCdF3:Cr3+,Li+晶体的ZFS参量,理论结果和实验符合很好。得到了F-离子向中心离子分别移动为ΔR1=0.00268nm,ΔR2=0.001nm,ΔR3=0.00165nm。

关 键 词:KCdF3:Cr3+  Li+  零场分裂  电荷补偿  局域结构
文章编号:1000-7032(2001)01-0012-04
收稿时间:2000-08-11
修稿时间:2000-08-11

Local Structure Study of Cr3+-Li+Centres in KCdF3 Crystals
YANG Zi yuan,QU Shao bo. Local Structure Study of Cr3+-Li+Centres in KCdF3 Crystals[J]. Chinese Journal of Luminescence, 2001, 22(1): 12-15
Authors:YANG Zi yuan  QU Shao bo
Affiliation:1. Department of Physics, Baoji College of Arts and Science, Baoji 721007, China;2. Xi’an Air Force Engineering Institute, Xi’an 710038, China
Abstract:The aim of the work is to study the local struture of KCdF3 doped with Cr3+ and Li+ ions by means of the quantitative relationship between the ZFS parameter and the crystal structure.The present work suggests that the tetragonal crystal field of Cr3+ ion in KCdF3:Cr3+,Li+ crystals comes from following two origins:(1) The equivalent charge caused by the charge compensation in the [001]-axis direction. (2) The lattice distortions of the nearest-neighbor fluorine coordination.In fact,when Cr3+ and Li+ ions doped into KCdF3 crystals, Cr3+ ions replace divalent Cd2+ ions. Owing to the difference in charge, mass, and radius between Cr3+ and Cd2+ ion, the lattice distortion occurs to the local structure of Cr3+-Li+ centres in KCdF3 crystals. Due to the charge compensation, a Cd2+ ion on [001]-axis will be replace by Li+ ion. Because of these, the local structure distorts and local point symmetry around Cr3+ changes from Oh to C4v. According to the idea,the relationship between the zero field splitting D and crystal structure for Cr3+ in KCdF3:Cr3+,Li+ crystals has been established by means of the superposition model and third order perturbation theory.The EPR zero field splitting parameter D has been investigated,taking account of both effect of lattice distortion and the equivalent charge.The calculated result(D=-0.06203cm-1) is in excellent agreement with experimental result(D=-0.06212(5)cm-1).Meanwhile,the results,the F- ion moves toward the central Cr3+ ion by ΔR1=0.00268nm,ΔR21=0.001nm,ΔR3=0.00165nm,are obtained.
Keywords:KCdF3:Cr3+   Li+  zero-field splitting  charge compensation  local structure
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