Interplay between Steps and Oxygen Vacancies on Curved TiO2(110)

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• 作者：Luis A. Miccio ; Martin Setvin ; Moritz Müller ; Mikel Abadía ; Ignacio Piquero ; Jorge Lobo-Checa ; Frederik Schiller ; Celia Rogero ; Michael Schmid ; Daniel Sánchez-Portal ; Ulrike Diebold ; J. Enrique Ortega
• 刊名：Nano Letters
• 出版年：2016
• 出版时间：March 9, 2016
• 年：2016
• 卷：16
• 期：3
• 页码：2017-2022
• 全文大小：438K
• ISSN：1530-6992

文摘

A vicinal rutile TiO₂(110) crystal with a smooth variation of atomic steps parallel to the [1–10] direction was analyzed locally with STM and ARPES. The step edge morphology changes across the samples, from [1–11] zigzag faceting to straight [1–10] steps. A step-bunching phase is attributed to an optimal (110) terrace width, where all bridge-bonded O atom vacancies (O_br vacs) vanish. The [1–10] steps terminate with a pair of 2-fold coordinated O atoms, which give rise to bright, triangular protrusions (S_t) in STM. The intensity of the Ti 3d-derived gap state correlates with the sum of O_br vacs plus S_t protrusions at steps, suggesting that both O_br vacs and steps contribute a similar effective charge to sample doping. The binding energy of the gap state shifts when going from the flat (110) surface toward densely stepped planes, pointing to differences in the Ti³⁺ polaron near steps and at terraces.