Liu Jing-Yuan, Chen Ling, Wu Li-Ming
Beijing Key Laboratory of Energy Conversion and Storage Materials, College of Chemistry, Beijing Normal University, Beijing, 100875, People's Republic of China.
Center for Advanced Materials Research, Advanced Institute of Natural Sciences, Beijing Normal University, Zhuhai, 519087, People's Republic of China.
Nat Commun. 2022 May 27;13(1):2966. doi: 10.1038/s41467-022-30716-7.
The argyrodite AgGaSe is a newly recognized high-efficiency thermoelectric material with an ultralow thermal conductivity; however, liquid-like Ag atoms are believed to cause poor stability and performance irreproducibility, which was evidenced even after the 1 measurement run. Herein, we demonstrate the abovementioned instability and irreproducibility are caused by standard thermoelectric sample hot-pressing procedure, during which high pressure promotes the 3-fold-coordinated Ag atoms migrate to 4-fold-coordinated sites with higher-chemical potentials. Such instability can be eliminated by a simple annealing treatment, driving the metastable Ag atoms back to the original sites with lower-chemical potentials as revealed by the valence band X-ray photoelectron chemical potential spectra and single crystal X-ray diffraction data. Furthermore, the hot-pressed-annealed samples exhibit great stability and TE property repeatability. Such a stability and repeatability has never been reported before. This discovery will give liquid-like materials great application potential.
硫银锗矿AgGaSe是一种新发现的具有超低热导率的高效热电材料；然而，人们认为类似液体的银原子会导致稳定性差和性能不可重复性，即使在一次测量运行后也能证明这一点。在此，我们证明上述不稳定性和不可重复性是由标准的热电样品热压程序引起的，在此过程中，高压促使三配位的银原子迁移到具有更高化学势的四配位位置。通过简单的退火处理可以消除这种不稳定性，价带X射线光电子能谱和单晶X射线衍射数据表明，这会驱使亚稳态的银原子回到具有较低化学势的原始位置。此外，热压退火后的样品表现出极大的稳定性和热电性能重复性。这种稳定性和重复性以前从未有过报道。这一发现将赋予类液体材料巨大的应用潜力。
