Ion conducting materials are critical components of batteries, fuel cells, and devices such as memristive switches. Analytical tools are therefore sought that allow the behavior of ions in solids to be monitored and analyzed with high spatial resolution and in real time. In principle, inelastic tunneling spectroscopy offers these capabilities. However, as its spectral resolution is limited by thermal softening of the Fermi–Dirac distribution, tunneling spectroscopy is usually constrained to cryogenic temperatures. This constraint would seem to render tunneling spectroscopy useless for studying ions in motion. Here, the first inelastic tunneling spectroscopy studies above room temperature are reported. For these measurements, high‐temperature‐stable tunnel junctions that incorporate within the tunnel barrier ultrathin layers for efficient proton conduction are developed. By analyzing the vibrational modes of OH bonds in BaZrO₃‐based heterostructures, the detection of protons with a spectral resolution of 20 meV at 400 K (full‐width‐at‐half maximum) is demonstrated. Overturning the hitherto existing prediction for the spectral resolution limit of 186 meV (5.4 k_BT ) at 400 K, this resolution enables high‐temperature tunneling spectroscopy of ion conductors. With these advances, inelastic tunneling spectroscopy constitutes a novel, valuable analytical tool for solid‐state ionics.

中文翻译：

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高温下的非弹性电子隧穿谱

离子导电材料是电池，燃料电池和忆阻开关等设备的关键组件。因此，寻求一种分析工具，以高空间分辨率和实时监测和分析固体中离子的行为。原则上，非弹性隧道光谱法提供了这些功能。但是，由于费米-狄拉克分布的热软化限制了它的光谱分辨率，因此隧道光谱通常局限于低温。这种限制似乎使隧道光谱学对研究运动中的离子毫无用处。在这里，首次报道了室温以上的非弹性隧道光谱研究。对于这些测量，开发了结合在隧道势垒超薄层中以实现有效质子传导的高温稳定隧道结。通过分析O的振动模式Ba基于BaZrO ₃的异质结构中的H键，证明了在400 K（最大半峰全宽）下具有20 meV光谱分辨率的质子检测。推翻了迄今为止在400 K下对光谱分辨率极限为186 meV（5.4 k _B T）的现有预测，该分辨率可实现离子导体的高温隧穿光谱。有了这些进展，非弹性隧穿光谱学就构成了一种用于固态离子的新颖而有价值的分析工具。