Flege J I, Krisponeit J-O, Höcker J, Hoppe M, Niu Y, Zakharov A, Schaefer A, Falta J, Krasovskii E E
Institute of Solid State Physics, University of Bremen, Otto-Hahn-Allee 1, 28359 Bremen, Germany; MAPEX Center for Materials and Processes, University of Bremen, 28359 Bremen, Germany.
Institute of Solid State Physics, University of Bremen, Otto-Hahn-Allee 1, 28359 Bremen, Germany; MAPEX Center for Materials and Processes, University of Bremen, 28359 Bremen, Germany.
Ultramicroscopy. 2017 Dec;183:61-66. doi: 10.1016/j.ultramic.2017.05.007. Epub 2017 May 10.
The complex structure and morphology of ultrathin praseodymia films deposited on a ruthenium(0001) single crystal substrate by reactive molecular beam epitaxy is analyzed by intensity-voltage low-energy electron microscopy in combination with theoretical calculations within an ab initio scattering theory. A rich coexistence of various nanoscale crystalline surface structures is identified for the as-grown samples, notably comprising two distinct oxygen-terminated hexagonal PrO(0001) surface phases as well as a cubic PrO(111) and a fluorite PrO(111) surface component. Furthermore, scattering theory reveals a striking similarity between the electron reflectivity spectra of praseodymia and ceria due to very efficient screening of the nuclear charge by the extra 4f electron in the former case.
通过强度-电压低能电子显微镜结合从头算散射理论中的理论计算，分析了通过反应分子束外延沉积在钌(0001)单晶衬底上的超薄镨薄膜的复杂结构和形态。对于生长态样品，确定了各种纳米级晶体表面结构的丰富共存，特别是包括两个不同的氧端接六方PrO(0001)表面相以及立方PrO(111)和萤石PrO(111)表面组分。此外，散射理论揭示了镨和二氧化铈的电子反射光谱之间存在显著相似性，这是由于在前一种情况下，额外的4f电子对核电荷进行了非常有效的屏蔽。
