Lithium ion dynamics in Li2S+GeS2+GeO2 glasses studied using 7Li NMR field-cycling relaxometry and line-shape analysis
Lithium ion dynamics in Li2S+GeS2+GeO2 glasses studied using 7Li NMR field-cycling relaxometry and line-shape analysis
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DOI：
10.1016/j.ssnmr.2015.06.004
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发表时间：
2015-09-01
影响因子：
3.2
通讯作者：
Vogel, Michael
中科院分区：
文献类型：
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作者：
Gabriel, Jan;Petrov, Oleg V.;Vogel, Michael
利用Li-7核磁共振研究了三元0.5 li (2)S + 0.5[(1-x)GeS2+xGeO(2)]玻璃锂离子导体中的离子跃迁运动。通过对该系统中“混合玻璃原效应”的研究，提出了系统中扩散势垒均匀随机变化的假设。我们利用传统的线形分析与新型的场循环弛豫测量相结合，可以测量宽频率和宽温度范围内离子跃迁运动的谱密度，从而确定活化能的分布。采用多指数自相关函数模型和幂律等待时间模型对Li-7核磁共振数据进行参数化。对这两种模型的仔细评估表明，对于单一（x=0.0）和混合（x=0.1）网络前玻璃，能量景观都是广泛不均匀的。激活势垒的高斯分布可以很好地描述多指数自相关函数模型。讨论了所用方法的适用性及其对离子运动微观细节的敏感性。(C) 2015爱思唯尔公司版权所有。
We use Li-7 NMR to study the ionic jump motion in ternary 0.5Li(2)S + 0.5[(1-x)GeS2+xGeO(2)] glassy lithium ion conductors. Exploring the "mixed glass former effect" in this system led to the assumption of a homogeneous and random variation of diffusion barriers in this system. We exploit that combining traditional line-shape analysis with novel field-cycling relaxometry, it is possible to measure the spectral density of the ionic jump motion in broad frequency and temperature ranges and, thus, to determine the distribution of activation energies. Two models are employed to parameterize the Li-7 NMR data, namely, the multi-exponential autocorrelation function model and the power-law waiting times model. Careful evaluation of both of these models indicates a broadly inhomogeneous energy landscape for both the single (x=0.0) and the mixed (x=0.1) network former glasses. The multi-exponential autocorrelation function model can be well described by a Gaussian distribution of activation barriers. Applicability of the methods used and their sensitivity to microscopic details of ionic motion are discussed. (C) 2015 Elsevier Inc. All rights reserved.