Investigations on the EPR parameters and defect structures due to Jahn-Teller effect for the Cu2+ and Ni+ centers in LiNbO3
Investigations on the EPR parameters and defect structures due to Jahn-Teller effect for the Cu2+ and Ni+ centers in LiNbO3
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DOI：
10.1016/j.jallcom.2018.02.209
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发表时间：
2018-05
影响因子：
6.2
通讯作者：
Huaming Zhang;W. Xiao
中科院分区：
文献类型：
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作者：
Huaming Zhang;W. Xiao
根据菱形拉长八面体和压缩八面体下3d9离子的微扰公式，对LiNbO3中杂质Cu2+和Ni+的EPR参数进行了理论研究。在这两个中心，杂质 Cu2+ 和 Ni+ 离子被认为占据了主体三角扭曲八面体 Li+ 位点，并且八面体分别经历了从三角伸长和压缩到菱形的 Jahn-Teller 扭曲。伸长的[CuO6]10−簇（和压缩的[NiO6]11−簇）归因于沿z轴遭受0.102Å的轴向伸长（和0.062Å的压缩），并且由于Jahn-Teller效应，平面键分别经历0.023Å（和0.032Å）的相对变化。基于上述晶格畸变计算出的EPR参数与实验数据相当吻合，并讨论了杂质中心的局部结构。
The EPR parameters of the impurity Cu2+and Ni+in LiNbO3are theoretically studied from the perturbation formulas for 3d9ions under rhombically elongated and compressed octahedra, respectively. In both centers, the impurity Cu2+and Ni+ions was ascribed to occupy the host trigonally-distorted octahedral Li+sites and the octahedrons experience the Jahn-Teller distortion from trigonal to rhombically -elongated and -compressed, respectively. The elongated [CuO6]10−cluster (and compressed [NiO6]11−cluster) are ascribed to suffering the axial elongation of 0.102 Å (and compression of 0.062 Å) along z-axis and the planar bonds are found to experience the relative variation of 0.023 Å (and 0.032 Å), respectively, due to the Jahn-Teller effect. The calculated EPR parameters based on the above lattice distortions agree reasonably with the experimental data, and the local structures of the impurity centers are discussed.