Photo-enhanced ionic conductivity across grain boundaries in polycrystalline ceramics
Photo-enhanced ionic conductivity across grain boundaries in polycrystalline ceramics
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DOI：
10.1038/s41563-021-01181-2
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发表时间：
2022-01-13
期刊：
影响因子：
41.2
通讯作者：
Tuller, Harry L.
中科院分区：
文献类型：
--
作者：
Defferriere, Thomas;Klotz, Dino;Tuller, Harry L.
晶界电导率的限制在材料科学中是普遍存在的。我们发现，上述带隙光照射可以降低固体离子导体的晶界电阻。具体而言，我们证明了在250摄氏度下，3摩尔% Gd掺杂的二氧化铈薄膜的晶界电导增加约3.5倍，并且其活化能在光照下从1.12降低到0.68 eV，而光致加热和电子电导率可以被排除作为所观察到的光离子效应的潜在来源。所提出的模型预测，光生电子降低与相邻晶粒之间的电荷载流子耗尽的空间电荷区相关的势垒高度。发现的光离子效应可以为开发在较低温度和/或更高效率下操作的新的电化学存储和转换技术铺平道路，并且可以进一步用于多晶固体中离子导电的快速和非接触式控制或诊断。现在示出了用带隙以上的光照射以降低模型钆掺杂的二氧化铈固体离子导体中的晶界电阻。
Grain boundary conductivity limitations are ubiquitous in material science. We show that illumination with above-bandgap light can decrease the grain boundary resistance in solid ionic conductors. Specifically, we demonstrate the increase of the grain boundary conductance of a 3 mol% Gd-doped ceria thin film by a factor of approximately 3.5 at 250 degrees C and the reduction of its activation energy from 1.12 to 0.68 eV under illumination, while light-induced heating and electronic conductivity could be excluded as potential sources for the observed opto-ionic effect. The presented model predicts that photo-generated electrons decrease the potential barrier heights associated with space charge zones depleted in charge carriers between adjacent grains. The discovered opto-ionic effect could pave the way for the development of new electrochemical storage and conversion technologies operating at lower temperatures and/or higher efficiencies and could be further used for fast and contactless control or diagnosis of ionic conduction in polycrystalline solids.Grain boundary conductivity limitations are ubiquitous in material science. Illumination with above-bandgap light is now shown to decrease grain boundary resistance in a model gadolinium-doped ceria solid ionic conductor.