Sapkota Pitambar, Aprahamian Ani, Chan Kwong Yu, Frentz Bryce, Macon Kevin T, Ptasinska Sylwia, Robertson Daniel, Manukyan Khachatur
Department of Physics, University of Notre Dame, Notre Dame, Indiana 46556, USA.
Department of Chemistry, University of Hong Kong, Pokfulam, Hong Kong.
J Chem Phys. 2020 Mar 14;152(10):104704. doi: 10.1063/1.5142619.
The influence of high-energy (1.6 MeV) Ar irradiation on the interfacial interaction between cerium oxide thin films (∼15 nm) with a SiO/Si substrate is investigated using transmission electron microscopy, ultrahigh vacuum x-ray photoelectron spectroscopy (XPS), and a carbon monoxide (CO) oxidation catalytic reaction using ambient pressure XPS. The combination of these methods allows probing the dynamics of vacancy generation and its relation to chemical interactions at the CeO/SiO/Si interface. The results suggest that irradiation causes amorphization of some portion of CeO at the CeO/SiO/Si interface and creates oxygen vacancies due to the formation of CeO at room temperature. The subsequent ultra-high-vacuum annealing of irradiated films increases the concentration of CeO with the simultaneous growth of the SiO layer. Interactions with CO molecules result in an additional reduction of cerium and promote the transition of CeO to a silicate compound. Thermal annealing of thin films exposed to oxygen or carbon monoxide shows that the silicate phase is highly stabile even at 450 °C.
利用透射电子显微镜、超高真空X射线光电子能谱（XPS）以及使用常压XPS的一氧化碳（CO）氧化催化反应，研究了高能（1.6 MeV）氩辐照对具有SiO/Si衬底的氧化铈薄膜（约15 nm）界面相互作用的影响。这些方法的结合使得能够探究CeO/SiO/Si界面处空位产生的动力学及其与化学相互作用的关系。结果表明，辐照导致CeO/SiO/Si界面处的部分CeO非晶化，并由于室温下CeO的形成而产生氧空位。辐照薄膜随后的超高真空退火增加了CeO的浓度，同时SiO层生长。与CO分子的相互作用导致铈的进一步还原，并促进CeO向硅酸盐化合物的转变。暴露于氧气或一氧化碳的薄膜的热退火表明，即使在450°C下，硅酸盐相也非常稳定。
