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首页> 外文期刊>The journal of physical chemistry, B. Condensed matter, materials, surfaces, interfaces & biophysical >Li Diffusion and the Effect of Local Structure on Li Mobility in Li2O~-SiO2 Glasses
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Li Diffusion and the Effect of Local Structure on Li Mobility in Li2O~-SiO2 Glasses

机译：Li2O〜-SiO2玻璃中Li的扩散及局部结构对Li迁移率的影响

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Aimed to improve the understanding of lithium migration mechanisms in ion conductors, this study focuses on Li dynamics in binary Li silicate glasses. Isotope exchange experiments and conductivity measurements were carried out to determine self-diffusion coefficients and activation energies for Li migration in Li2Si3O7 and Li2Si6O_(13) glasses. Samples of identical composition but different isotope content were combined for diffusion experiments in couples or triples. Diffusion profiles developed between 511 and 664 K were analyzed by femtosecond laser ablation combined with multiple collector inductively coupled plasma mass spectrometry (fs LA-MC-ICP-MS) and secondary ion mass spectrometry (SIMS). Analyses of diffusion profiles and comparison of diffusion data reveal that the isotope effect of lithium diffusion in silicate glasses is rather small, consistent with classical diffusion behavior. Ionic conductivity of glasses was measured between 312 and 675 K. The experimentally obtained self-diffusion coefficient, D_(IE) and ionic diffusion coefficient, D_σ, derived from specific DC conductivity provided information about correlation effects during Li diffusion. The D_(IE)/D_σ is higher for the trisilicate (0.27 ± 0.05) than that for the hexasilicate (0.17 ± 0.02), implying that increasing silica content reduces the efficiency of Li jumps in terms of long-range movement. This trend can be rationalized by structural concepts based on nuclear magnetic resonance (NMR) and Raman spectroscopy as well as molecular dynamic simulations, that is, lithium is percolating in low-dimensional, alkali-rich regions separated by a silica-rich matrix.
机译：为了增进对离子导体中锂迁移机理的理解，本研究着重于二元硅酸锂玻璃中的锂动力学。进行了同位素交换实验和电导率测量，以确定Li2Si3O7和Li2Si6O_（13）玻璃中Li迁移的自扩散系数和活化能。将组成相同但同位素含量不同的样品合并成对或三对进行扩散实验。通过飞秒激光烧蚀结合多收集器电感耦合等离子体质谱（fs LA-MC-ICP-MS）和二次离子质谱（SIMS）分析了在511 K和664 K之间形成的扩散曲线。扩散曲线的分析和扩散数据的比较表明，锂在硅酸盐玻璃中的扩散同位素效应很小，与经典的扩散行为一致。在312至675 K之间测量了玻璃的离子电导率。从比直流电导率得出的实验得出的自扩散系数D_（IE）和离子扩散系数D_σ提供了有关Li扩散过程中相关效应的信息。三硅酸盐的D_（IE）/D_σ高于六硅酸盐的D_（IE）/D_σ（0.17±0.02），这意味着增加二氧化硅含量会降低锂在远距离运动中的跳跃效率。可以通过基于核磁共振（NMR）和拉曼光谱以及分子动力学模拟的结构概念来合理化这种趋势，也就是说，锂在由富含二氧化硅的基质隔开的低维，富含碱的区域中渗透。

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