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Issue 13, 2006
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Pressure-dependent Ni–O phase transitions and Ni oxide formation on Pt(111): An in situSTM study at elevated temperatures

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Abstract

Growth, atomic structure and O2 partial pressure dependent phase transitions of Ni–O structures and thin NiO films on Pt(111) have been studied using scanning tunnelling microscopy (STM), low-energy electron diffraction (LEED), and Auger electron spectroscopy (AES). In situ STM experiments were performed during film growth by reactive metal deposition at elevated temperatures (400–550 K) and variable O2 pressure. Depending on the substrate temperature, one-dimensional network-like Ni–O structures and islands with (7 × 1) and (4 × 2) reconstructions are formed during the initial stages of growth. These structures transform reversibly to a (2 × 2) reconstruction in a narrow O2 pressure range of 1.5–2 × 10−6 mbar and can be monitored by in situ STM. Upon reduction of the O2 pressure to <10−10 mbar pseudomorphic Ni monolayers are obtained. The defect-free ordering of Ni atoms on Pt(111) in a single stacking domain indicates an O-surfactant induced growth mode. The structural properties of the O2 pressure-dependent Ni–O phases are discussed in a simple model assuming NiO(001)-like atomic arrangements in the adsorbate overlayer. At higher coverage stable (111)-oriented NiO islands grow in a three-dimensional mode.

Graphical abstract: Pressure-dependent Ni–O phase transitions and Ni oxide formation on Pt(111): An in situ STM study at elevated temperatures

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Article information


Submitted
14 Nov 2005
Accepted
30 Jan 2006
First published
20 Feb 2006

Phys. Chem. Chem. Phys., 2006,8, 1575-1583
Article type
Paper

Pressure-dependent Ni–O phase transitions and Ni oxide formation on Pt(111): An in situ STM study at elevated temperatures

Ch. Hagendorf, R. Shantyr, H. Neddermeyer and W. Widdra, Phys. Chem. Chem. Phys., 2006, 8, 1575
DOI: 10.1039/B516070G

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