Operando characterization provides direct insight into material response under application conditions and it is essential to understand the stability limits of thermoelectric materials and their decomposition mechanisms. An operando setup capable of maintaining a thermal gradient while running DC current through a bar-shaped sample has been developed. Under operating conditions, X-ray scattering data can be measured along the sample to obtain spatially resolved structural knowledge in concert with measurement of electrical resistance and the Seebeck coefficient. Here thermoelectric β-Zn₄Sb₃, which is a mixed ionic–electronic conductor, is studied, and a significant temperature dependence of the Zn migration is directly observed. Measurements with the thermal gradient applied either along or opposite to the DC current establish that the ion migration is an electrochemical effect rather than a thermodiffusion. Consideration of only the applied critical voltage or current density is insufficient for deducing the stability limits and structural integrity of materials with temperature-dependent ion mobility. The present operando setup is not limited to studies of thermoelectric materials, and it also lends itself to studies of, for example, ion diffusion in solid-state electrolytes or structural transformations in solid-state reactions.

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热电材料的操作结构研究

操作数表征提供了对应用条件下材料响应的直接洞察，了解热电材料的稳定性极限及其分解机制至关重要。已经开发出一种能够在直流电流通过条形样品时保持热梯度的操作设置。在操作条件下，可以沿着样品测量 X 射线散射数据，以获得与电阻和塞贝克系数测量相一致的空间分辨结构知识。这里热电 β-Zn ₄ Sb ₃研究了混合离子-电子导体，并直接观察到 Zn 迁移的显着温度依赖性。沿直流电流或与直流电流相反应用的热梯度测量确定离子迁移是电化学效应而不是热扩散。仅考虑施加的临界电压或电流密度不足以推断具有温度依赖性离子迁移率的材料的稳定性极限和结构完整性。目前的操作设置不仅限于热电材料的研究，它还有助于研究，例如，固态电解质中的离子扩散或固态反应中的结构转变。