Wilkening M, Küchler W, Heitjans P
Institute of Physical Chemistry, University of Hannover, Callinstr. 3-3a, D-30167 Hannover, Germany.
Phys Rev Lett. 2006 Aug 11;97(6):065901. doi: 10.1103/PhysRevLett.97.065901. Epub 2006 Aug 8.
7Li stimulated-echo NMR and classical relaxation NMR techniques are jointly used for the first time for a comprehensive investigation of Li diffusion in layer-structured Li0.7TiS2. One single 2D Li diffusion process was probed over a dynamic range of almost 10 orders of magnitude. So far, this is the largest dynamic range being measured by 7Li NMR spectroscopy directly, i.e., without the help of a specific theoretical model. The jump rates obey a strict Arrhenius law, determined by an activation energy of 0.41(1) eV and a preexponential factor of 6.3(1)x10(12) s-1, and range between 1x10(-1) s-1 and 7.8x10(8) s-1 (148-510 K). Ultraslow Li jumps in the kHz to sub-Hz range were measured directly by recording 7Li spin-alignment correlation functions. The temperature and, in particular, the frequency dependence of the relaxation rates fully agree with results expected for 2D diffusion.
首次联合使用7Li受激回波核磁共振和经典弛豫核磁共振技术，对层状结构Li0.7TiS2中的锂扩散进行全面研究。在近10个数量级的动态范围内探测到一个单一的二维锂扩散过程。到目前为止，这是通过7Li核磁共振光谱直接测量到的最大动态范围，即无需特定理论模型的帮助。跳跃率遵循严格的阿仑尼乌斯定律，由0.41(1) eV的活化能和6.3(1)×10(12) s-1的指前因子决定，范围在1×10(-1) s-1至7.8×10(8) s-1之间（148 - 510 K）。通过记录7Li自旋排列相关函数直接测量了kHz至亚Hz范围内的超慢锂跳跃。弛豫率的温度依赖性，特别是频率依赖性，与二维扩散预期的结果完全一致。
