Applied Physics and Semiconductor Spectroscopy, Brandenburg University of Technology Cottbus-Senftenberg, 03046 Cottbus, Germany.
Institute of Solid State Physics, University of Bremen, 28359 Bremen, Germany.
Ultramicroscopy. 2023 Aug;250:113755. doi: 10.1016/j.ultramic.2023.113755. Epub 2023 May 9.
We have used low-energy electron microscopy (LEEM), micro-illumination low-energy electron diffraction (µLEED) supported by ab initio calculations, and X-ray absorption spectroscopy (XAS) to investigate in-situ and in real-time the structural properties of SmO deposits grown on Ru(0001), a rare-earth metal oxide model catalyst. Our results show that samarium oxide grows in a hexagonal A-SmO phase on Ru(0001), exhibiting a (0001) oriented-top facet and (113) side facets. Upon annealing, a structural transition from the hexagonal to cubic phase occurs, in which the Sm cations exhibit the +3 oxidation state. The unexpected initial growth in the A-SmO hexagonal phase and its gradual transition to a mixture with cubic C-SmO showcases the complexity of the system and the critical role of the substrate in the stabilization of the hexagonal phase, which was previously reported only at high pressures and temperatures for bulk samaria. Besides, these results highlight the potential interactions that Sm could have with other catalytic compounds with respect to the here gathered insights on the preparation conditions and the specific compounds with which it interacts.
我们使用低能电子显微镜（LEEM）、微光照低能电子衍射（µLEED）和基于第一性原理计算的 X 射线吸收光谱（XAS），原位实时研究了 SmO 沉积物在 Ru(0001)上的结构特性，Ru(0001) 是一种稀土金属氧化物模型催化剂。我们的结果表明，氧化钐在 Ru(0001)上以六方 A-SmO 相生长，呈现出（0001）取向的顶尖面和（113）侧基面。退火时，会发生从六方相到立方相的结构转变，其中 Sm 阳离子呈现 +3 氧化态。出乎意料的是，初始生长为 A-SmO 六方相，并且逐渐转变为与立方 C-SmO 的混合物，这展示了该体系的复杂性，以及衬底在稳定六方相方面的关键作用，此前仅在高压和高温下对于块状钐才报道过六方相。此外，这些结果突出了 Sm 与其他催化化合物之间可能存在的相互作用，这些结果有助于深入了解制备条件以及与 Sm 相互作用的特定化合物。
