Li+ ionic diffusion and vacancy ordering in β-LiGa
Li+ ionic diffusion and vacancy ordering in β-LiGa
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β-LiGa 中 Li+ 离子扩散和空位排序
DOI：
10.1039/b602445a
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发表时间：
2007
影响因子：
3.4
通讯作者：
K. Kuriyama
中科院分区：
文献类型：
--
作者：
K. Nakamura;K. Motoki;Y. Michihiro;T. Kanashiro;M. Yahagi;H. Hamanaka;K. Kuriyama
用~ 7 Li和~（71）Ga NMR研究了半金属锂β-LiGa中Li ~+离子的运动和空位有序性。50原子% Li样品中7 Li核的自旋-晶格弛豫速率T−11的温度依赖性在175 K附近显示出一个不对称的宽峰，并被解释为Li+离子的快速扩散。使用非德拜型弛豫模型估计跳跃的激活能为0.11 eV。在44和47原子% Li样品中，7 Li核的T−11温度依赖性分别在225和195 K处观察到陡峭的峰。这些反常峰的起源归因于Li+空位的有序-无序转变。在200 K以上测量的71 Ga核的T-11的温度依赖性被解释为由于移动的Li+离子引起的71 Ga核处的电场梯度波动引起的弛豫。由71 Ga核的T−11估算的Li+离子扩散活化能与由7 Li核的T−11估算的相当。
7Li and 71Ga NMR measurements have been performed to study the Li+ ionic motion and vacancy ordering in the lithium semimetal β-LiGa. The temperature dependence of the spin–lattice relaxation rate, T−11 of the 7Li nuclei in the 50 atom% Li sample shows an asymmetric broad peak around 175 K and is interpreted in terms of fast Li+ ionic diffusion. The activation energy of hopping is estimated as 0.11 eV using a non-Debye type relaxation model. In the temperature dependence of T−11 of the 7Li nuclei in 44 and 47 atom% Li samples, steep peaks are observed at 225 and 195 K, respectively. The origin of these anomalous peaks is attributed to the order–disorder transformation of Li+ vacancies. The temperature dependence of T−11 of the 71Ga nuclei measured above 200 K is interpreted in terms of the relaxation originating from the fluctuation of the electric field gradient at the 71Ga nuclei due to mobile Li+ ions. The activation energy for the Li+ ionic diffusion estimated from T−11 of the 71Ga nuclei is comparable with that obtained from T−11 of the 7Li nuclei.