Local decomposition of NiO ultra-thin films formed on Ni(111)

Kitakatsu, N.; Maurice, Vincent; Marcus, Philippe

doi:10.1016/s0039-6028(98)00372-0

Cited by 54 publications

(45 citation statements)

References 46 publications

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“…Comparable integral intensities of the oxide and substrate LEED spots are observed at about 620 K. This behavior suggests an Ostwald-like ripening process, in which smaller patches either dissolve or coalesce to form larger oxide islands, which yet remain too small to be im-aged in LEEM mode. These findings confirm the results of a scanning tunneling microscopy study that reported an increase in domain size by about a factor of two after annealing to 700 K. 42 Finally, at a temperature of 820 K, these islands have completely disappeared, and the original LEED pattern of the clean substrate is restored.…”

Section: B Oxidation Pathway At Room Temperaturesupporting

confidence: 88%

Self-limited oxide formation in Ni(111) oxidation

et al. 2011

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The oxidation of the Ni(111) surface is studied experimentally with low energy electron microscopy and theoretically by calculating the electron reflectivity for realistic models of the NiO/Ni(111) surface with an ab initio scattering theory. Oxygen exposure at 300 K under ultrahigh-vacuum conditions leads to the formation of a continuous NiO(111)-like film consisting of nanosized domains. At 750 K, we observe the formation of a nano-heterogeneous film composed primarily of NiO (111) surface oxide nuclei, which exhibit virtually the same energy-dependent reflectivity as in the case of 300 K and which are separated by oxygen-free Ni(111) terraces. The scattering theory explains the observed normal incidence reflectivity R(E) of both the clean and the oxidized Ni(111) surface. At low energies R(E) of the oxidized surface is determined by a forbidden gap in the k = 0 projected energy spectrum of the bulk NiO crystal. However, for both low and high temperature oxidation a rapid decrease of the reflectivity in approaching zero kinetic energy is experimentally observed. This feature is shown to characterize the thickness of the oxide layer, suggesting an average oxide thickness of two NiO layers.

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Section: B Oxidation Pathway At Room Temperaturesupporting

confidence: 88%

Self-limited oxide formation in Ni(111) oxidation

et al. 2011

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“…We note that a (4×2) superstructure with a very similar STM appearance has also been reported recently by Hagendorf et al for a Ni-oxide monolayer on Pt(111) [8]. A two-dimensional (√3×2) structure has been observed in STM during the decomposition of NiO(111) thin films on Ni(111) [6], which looks very similar to that shown in Fig. 6d, but with a twice smaller unit cell.…”

Section: Oxygen-rich Regime: 2 × 10supporting

confidence: 87%

“…We suspect that due to the poor resolution in the latter STM images, the subtle difference in the image contrast between a (2√3×2) and a (√3×2) unit cell could not be resolved, which may thus have been incorrectly assigned. Kitakatsu et al have interpreted this structure as residual bulk NiO rows, aligned along the substrate b112> directions [6]. These findings suggest that the (2√3×2) monolayer can be considered as an intermediate phase between an interface-stabilized oxide layer, whose structure is typically strongly substrate dependent, and a bulk oxide.…”

Section: Oxygen-rich Regime: 2 × 10mentioning

confidence: 99%

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Surface structure of nickel oxide layers on a Rh(111) surface

et al. 2013

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The formation of nickel oxide nanolayers by oxidizing Ni overlayers on Rh(111) has been investigated and their structures are reported as a function of the nickel coverage and oxygen pressure. Scanning tunneling microscopy (STM), low-energy electron diffraction (LEED), X-ray photoelectron spectroscopy (XPS) and diffraction (XPD), and high-resolution electron energy loss spectroscopy (HREELS) have been applied to characterize the structure and stoichiometry of the nickel oxide nanolayers. Several different phases have been observed depending on the strain state of the metallic Ni overlayers. For the pseudomorphic Ni monolayer, two distinctly different oxide phases with (6 ×1)-Ni 5 O 5 and (2√3×2)-Ni 8 O 10 structures have been identified at oxygen-poor (p=5×10 −8 mbar) and oxygen-rich (p≥1×10 −6 mbar) conditions, respectively. Above one monolayer, where the Ni layers are relaxed, bulk-like NiO(100) films form at the O-rich conditions, whereas chemisorbed-type p(2 ×2)O\Ni(111) layers develop in the O-poor regime. X-ray photoelectron diffraction analysis has provided additional insight into the relaxation mechanism and the detailed atomic structure of the Ni-oxide nanolayers.

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“…Many studies have been concerned the reduction of oxidized nickel [5][6][7] and some recent work dealt with heating the NiO surface [8][9][10] and nickel-supported catalysts [10][11][12][13][14][15] by the different reduced source and sintering technologies.…”

Section: Introductionmentioning

confidence: 99%

Recovery and Reduction of Spent Nickel Oxide Catalyst via Plasma Sintering Technique

Wong

Lin

Chang

et al. 2006

Plasma Chem Plasma Process

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A thermal plasma process for the recovery and reduction of nickel oxide in the spent nickel-based catalyst (NiO/SiO 2 ) was developed. The spent catalyst was sintered at >1,500°C under plasma condition and the nickel oxide therein was reduced to nickel, which was proven by XRD and EDX. By application of SEM and GC technique, the organic tar on the surface of the spent catalyst was found to decomposed and converted to syngas (CO, CO 2 , and H 2 ), which might be the reducing agents in the process. A gasification mechanism for the generation of syngas and the reduction of nickel oxide under plasma conditions was proposed.

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Local decomposition of NiO ultra-thin films formed on Ni(111)

Cited by 54 publications

References 46 publications

Self-limited oxide formation in Ni(111) oxidation

Self-limited oxide formation in Ni(111) oxidation

Surface structure of nickel oxide layers on a Rh(111) surface

Recovery and Reduction of Spent Nickel Oxide Catalyst via Plasma Sintering Technique

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