skip to main content
OSTI.GOV title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: Microstructure of the Native Oxide Layer on Ni and Cr-doped Ni Nanoparticles

Abstract

Metallic or alloy nanoparticles exposed to air at room temperature will be instantaneously oxidized and covered by an oxide layer. However, for most cases, the true structural nature of the oxide layer formed at this stage is hard to determine. In this paper, we report the structure, morphology, and electronic structure (the density of state of both valence and conduction bands measured by a combination of XPS and EELS) of pure Ni and Cr-doped Ni nanoparticles synthesized using a cluster deposition process. Structural characterization carried out at the atomic level using aberration corrected high resolution transmission electron microscopy (HRTEM) in combination with electron and x-ray diffractions reveals that both pure Ni and Cr-doped Ni particles exposed to air at room temperature similarly possesses a core-shell structure of metal core covered by an oxide layer of typically 1.6 nm in thickness. There exists a critical size of ~ 6 nm, below which the particle is fully oxidized. The oxide particle corresponds to the rock-salt structured NiO and is faceted on the (001) planes. XPS of O-1s shows a strong peak that is attributed to (OH)-, which in combination with the atomic level HRTEM imaging indicates that the very top layer ofmore » the oxide is hydrolyzed as Ni(OH)2. Chemical composition analysis using EDS, EELS, and XPS indicates that the Cr dopant at the level of ~ 5at% forms solid solution with the Ni lattice. The Cr shows no segregation on the surface or preferential oxidation during the initial oxidation.« less

Authors:
; ; ; ; ; ;
Publication Date:
Research Org.:
Pacific Northwest National Laboratory (PNNL), Richland, WA (US), Environmental Molecular Sciences Laboratory (EMSL)
Sponsoring Org.:
USDOE
OSTI Identifier:
1034584
Report Number(s):
PNNL-SA-76189
39399; KP1704020; KC0201020; TRN: US201203%%634
DOE Contract Number:  
AC05-76RL01830
Resource Type:
Journal Article
Journal Name:
Journal of Nanoscience and Nanotechnology, 11(10):8488-8497
Additional Journal Information:
Journal Volume: 11; Journal Issue: 10
Country of Publication:
United States
Language:
English
Subject:
77 NANOSCIENCE AND NANOTECHNOLOGY; ALLOYS; CHEMICAL COMPOSITION; CRITICAL SIZE; DEPOSITION; ELECTRONIC STRUCTURE; ELECTRONS; LASERS; MICROSTRUCTURE; MORPHOLOGY; OXIDATION; OXIDES; RESOLUTION; SALT DEPOSITS; SEGREGATION; SOLID SOLUTIONS; TRANSMISSION ELECTRON MICROSCOPY; VALENCE; X-RAY DIFFRACTION; X-RAY PHOTOELECTRON SPECTROSCOPY; Core-shell; structure; Ni nanoparticles; Cr-doped Ni nanoparticles; electronic structure; HRTEM; surface; layer; Environmental Molecular Sciences Laboratory

Citation Formats

Wang, Chong M., Baer, Donald R., Bruemmer, Stephen M., Engelhard, Mark H., Bowden, Mark E., Sundararajan, J. A., and Qiang, You. Microstructure of the Native Oxide Layer on Ni and Cr-doped Ni Nanoparticles. United States: N. p., 2011. Web. doi:10.1166/jnn.2011.4964.
Wang, Chong M., Baer, Donald R., Bruemmer, Stephen M., Engelhard, Mark H., Bowden, Mark E., Sundararajan, J. A., & Qiang, You. Microstructure of the Native Oxide Layer on Ni and Cr-doped Ni Nanoparticles. United States. doi:10.1166/jnn.2011.4964.
Wang, Chong M., Baer, Donald R., Bruemmer, Stephen M., Engelhard, Mark H., Bowden, Mark E., Sundararajan, J. A., and Qiang, You. Sat . "Microstructure of the Native Oxide Layer on Ni and Cr-doped Ni Nanoparticles". United States. doi:10.1166/jnn.2011.4964.
@article{osti_1034584,
title = {Microstructure of the Native Oxide Layer on Ni and Cr-doped Ni Nanoparticles},
author = {Wang, Chong M. and Baer, Donald R. and Bruemmer, Stephen M. and Engelhard, Mark H. and Bowden, Mark E. and Sundararajan, J. A. and Qiang, You},
abstractNote = {Metallic or alloy nanoparticles exposed to air at room temperature will be instantaneously oxidized and covered by an oxide layer. However, for most cases, the true structural nature of the oxide layer formed at this stage is hard to determine. In this paper, we report the structure, morphology, and electronic structure (the density of state of both valence and conduction bands measured by a combination of XPS and EELS) of pure Ni and Cr-doped Ni nanoparticles synthesized using a cluster deposition process. Structural characterization carried out at the atomic level using aberration corrected high resolution transmission electron microscopy (HRTEM) in combination with electron and x-ray diffractions reveals that both pure Ni and Cr-doped Ni particles exposed to air at room temperature similarly possesses a core-shell structure of metal core covered by an oxide layer of typically 1.6 nm in thickness. There exists a critical size of ~ 6 nm, below which the particle is fully oxidized. The oxide particle corresponds to the rock-salt structured NiO and is faceted on the (001) planes. XPS of O-1s shows a strong peak that is attributed to (OH)-, which in combination with the atomic level HRTEM imaging indicates that the very top layer of the oxide is hydrolyzed as Ni(OH)2. Chemical composition analysis using EDS, EELS, and XPS indicates that the Cr dopant at the level of ~ 5at% forms solid solution with the Ni lattice. The Cr shows no segregation on the surface or preferential oxidation during the initial oxidation.},
doi = {10.1166/jnn.2011.4964},
journal = {Journal of Nanoscience and Nanotechnology, 11(10):8488-8497},
number = 10,
volume = 11,
place = {United States},
year = {2011},
month = {10}
}