Fast Na+ Ion Conduction in NASICON-Type Na3.4Sc2(SiO4)0.4(PO4)2.6 Observed by 23Na NMR Relaxometry

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• 作者：Maximilian Kaus ; Marie Guin ; Murat Yavuz ; Michael Knapp ; Frank Tietz ; Olivier Guillon ; Helmut Ehrenberg ; Sylvio Indris
• 刊名：Journal of Physical Chemistry C
• 出版年：2017
• 出版时间：January 26, 2017
• 年：2017
• 卷：121
• 期：3
• 页码：1449-1454
• 全文大小：425K
• ISSN：1932-7455

文摘

The bulk diffusion of Na in Na_3.4Sc₂(SiO₄)_0.4(PO₄)_2.6 was investigated by ²³Na NMR relaxometry in the temperature range from 250 to 670 K. These measurements reveal fast Na diffusion with hopping rates of 3 × 10⁸ s^–1 for the Na⁺ ions at 350 K and activation barriers for single Na⁺ ion jumps of (0.20 ± 0.01) eV. From these values a diffusion coefficient of D = 6.4 × 10^–12 m²/s and a Na ion conductivity of σ_Na = 4 mS/cm (both at 350 K) can be estimated. Measurements on two samples, one stored in air and one stored in Ar, do not show significant differences, which reveals that these NMR measurements are probing the bulk diffusion while conductivity measurements usually are also influenced by grain boundaries that can be affected by the moisture level during storage.