Abstract We used temperature-programmed desorption (TPD), low energy electron diffraction (LEED) and X-ray photoelectron spectroscopy (XPS) to investigate the oxidation of a well-ordered c-Tb2O3(111) thin film supported on Pt(111) by gaseous oxygen atoms in ultrahigh vacuum. Our results provide evidence that the c-Tb2O3 film oxidizes through the sequential development of the stoichiometric ι-Tb7O12 and δ-Tb11O20 phases, followed by the formation of a variable oxygen concentration α-TbOx phase up to x = 2. The ι and δ-phases decompose to yield sharp O2 TPD peaks at about 780 and 640 K, while the α-phase evolves O2 between ~450 and 600 K during TPD. Quantitative analysis shows that changes in the XPS Tb 3d and 4d spectra caused by oxidation agree well with our estimates of the TbOx film stoichiometry determined from TPD. We observe a well-defined LEED pattern for ι-Tb7O12(111) after heating the oxidized film to ~700 K. In contrast, several observations, including incomplete ι → δ conversion, lack of an observable LEED pattern for the δ-Tb11O20 phase, and sensitivity of α-phase formation to thermal aging of the film, indicate that the δ and α-phases develop under kinetic control for the conditions studied, such that the phases decompose in UHV at temperatures lower than those needed for these phases to stabilize into more crystalline and uniform arrangements.

中文翻译：

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通过化学计量相的顺序形成氧化 c-Tb2O3(111) 薄膜

摘要 我们使用程序升温脱附 (TPD)、低能电子衍射 (LEED) 和 X 射线光电子能谱 (XPS) 研究了负载在 Pt(111) 上的有序 c-Tb2O3(111) 薄膜的氧化通过超高真空中的气态氧原子。我们的结果提供证据表明，c-Tb2O3 膜通过化学计量的 ι-Tb7O12 和 δ-Tb11O20 相的顺序发展进行氧化，然后形成可变氧浓度的 α-TbOx 相，直至 x = 2。ι 和 δ - 相分解以在约 780 和 640 K 处产生尖锐的 O2 TPD 峰，而在 TPD 期间，α 相在 ~450 和 600 K 之间产生 O2。定量分析表明，由氧化引起的 XPS Tb 3d 和 4d 光谱的变化与我们对 TPD 确定的 TbOx 薄膜化学计量的估计非常吻合。