论文标题
lialo $ _2 $的声子和锂扩散
Phonons and Lithium diffusion in LiAlO$_2$
论文作者
论文摘要
我们报告了基于非弹性中子中子散射（INS）测量γ-lialo $ _2 $ _2 $ _2 $ _2 $从473 K到1073 k的状态状态密度（DOS）的调查子和锂扩散的研究，并与AB-Initio Molecular Dynamics（AIMD）拟合。我们发现，与LI振动相关的声子模式在变暖上宽广，如测得的声子DOS所反映并在模拟中复制。此外，AIMD模拟探测了完美的结晶相（γ-二极管$ _2 $）的锂扩散的性质，以及具有锂空位和相关无定形相的结构。在高温下的三个结构的AIMD模拟中观察到几乎液态的超级离子扩散。完美结构，空置结构和无定形相的预测的发作温度分别为1800 K，1200 K和600 K。在理想的结构中，Li原子显示相关的跳跃。虽然在空缺结构中都可以看到简单和相关的跳跃，并且跳跃和连续扩散的混合物发生在无定形结构中。此外，我们发现，在所有情况下，Li-diffusion都受到邻近Alo4四面体的巨大库幅度的青睐，并且由于ALO4四面体方向的广泛分布，无定形结构均打开了其他扩散途径。
We report on investigations of phonons and lithium diffusion in LiAlO$_2$ based on inelastic neutron scattering (INS) measurements of the phonon density of states (DOS) in γ-LiAlO$_2$ from 473 K to 1073 K, complemented with ab-initio molecular dynamics (AIMD) simulations. We find that phonon modes related to Li vibrations broaden on warming as reflected in the measured phonon DOS and reproduced in simulations. Further, the AIMD simulations probe the nature of lithium diffusion in the perfect crystalline phase (γ-LiAlO$_2$), as well as in a structure with lithium vacancies and a related amorphous phase. Almost liquid-like super-ionic diffusion is observed in AIMD simulations of the three structures at high temperatures; with predicted onset temperatures of 1800 K, 1200 K, and 600 K in the perfect structure, vacancy structure and the amorphous phase, respectively. In the ideal structure, the Li atoms show correlated jumps; while simple and correlated jumps are both seen in the vacancy structure, and a mix of jumps and continuous diffusion occur in the amorphous structure. Further, we find that the Li-diffusion is favored in all cases by a large librational amplitude of the neighbouring AlO4 tetrahedra, and that the amorphous structure opens additional diffusion pathways due to a broad distribution of AlO4 tetrahedra orientations.
