Theoretical studies of the spin Hamiltonian parameters and the local structures for the tetragonal Cu2+ centers in the LKB glasses
Theoretical studies of the spin Hamiltonian parameters and the local structures for the tetragonal Cu2+ centers in the LKB glasses
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DOI：
10.1016/j.jnoncrysol.2011.02.009
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发表时间：
2011-05
影响因子：
3.5
通讯作者：
Huaming Zhang;Shao-yi Wu;Zhi-Hong Zhang
中科院分区：
文献类型：
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作者：
Huaming Zhang;Shao-yi Wu;Zhi-Hong Zhang
利用3d 9离子在四面体拉长八面体中的自旋哈密顿参数（g因子g <$，g <$和超精细结构常数A <$，A <$）的高阶微扰公式，对锂钾硼酸盐（LKB）玻璃xLi 2 O·（30−x）·K2 O·70 B2 O3（0≤x≤25）中Cu 2+中心的自旋哈密顿参数（g因子g <$，g <$）进行了理论研究.由于Jahn-Teller效应，发现LKB玻璃中的[CuO 6]10-团簇沿四轴方向的相对伸长约为沿着3%。g因子的浓度依赖性通过立方场参数Dq的近似线性减小以及由于晶胞体积或键长的轻微膨胀而导致的共价因子N和相对延伸率ρ的增加来说明。同时，超精细结构常数的缓慢非线性增长被描述为由于系统的四方性的增加而导致的芯极化常数κ随x的粗略指数增长。理论自旋哈密顿参数及其浓度依赖性与实验数据符合良好。为了评价本文理论模型和公式的有效性和适用性，还分析了类似锂钠硼（LNB）xLi 2 O·（30−x）·Na 2 O·70 B2 O3（5≤x≤25mol%）玻璃中Cu 2+中心的EPR结果，并与LKB系统中的结果进行了比较。
The spin Hamiltonian parameters (g factors g∥, g⊥and the hyperfine structure constants A∥, A⊥) for the Cu2+centers in the lithium potassium borate (LKB) glasses xLi2O·(30−x)·K2O·70B2O3(0≤x≤25) were theoretically studied using the high-order perturbation formulas of these parameters for a 3d9ion in a tetragonally elongated octahedron. The [CuO6]10−clusters in the LKB glasses are found to suffer the relative elongations of about 3% along the tetragonal axis due to the Jahn–Teller effect. The concentration dependences of the g factors are illustrated by the approximately linear decrease of the cubic field parameter Dq as well as the increases of the covalency factor N and the relative elongation ratio ρ due to the slight expansion of the cell volume or bond lengths with increasing the Li2O concentration x. Meanwhile, the slow non-linear increases of the hyperfine structure constants are described as the rough exponential increase of the core polarization constant κ with x due to the increase of the tetragonality of the systems. The theoretical spin Hamiltonian parameters and their concentration dependences show good agreement with the experimental data. To evaluate validity and applicability of the present theoretical model and formulas, the EPR results of the Cu2+centers in similar lithium sodium borate (LNB) xLi2O·(30−x)·Na2O·70B2O3(5≤x≤25mol%) glasses are also analyzed and compared with those in the LKB systems using the uniform model and formulas.