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Title: Squeezed nanocrystals: equilibrium configuration of metal clusters embedded beneath the surface of a layered material

Abstract

Shapes of functional metallic nanocrystals, typically synthesized either free in solution or supported on surfaces, are key for controlling properties. Here, we consider a novel new class of metallic nanocrystals, copper clusters embedded near the surface of graphite, which can be considered a model system for metals embedded beneath surfaces of layered materials, or beneath supported membranes. We develop a continuum elasticity (CE) model for the equilibrium shape of these islands, and compare its predictions with experimental data. The CE model incorporates appropriate surface energy, adhesion energies, and strain energy. The agreement between the CE model and the data is—with one exception—excellent, both qualitatively and quantitatively, and is achieved with a single adjustable parameter. The model predicts that the embedded island shape is invariant with size, manifest both by constant side slope and by constant aspect ratio. This prediction is rationalized by dimensional analysis of the relevant energetic contributions. The aspect ratio (width : height) of an embedded Cu cluster is much larger than that of a supported but non-embedded Cu cluster, due to resistance of the graphene membrane to deformation. Experimental data diverge from the model predictions only in the case of the aspect ratio of small islands, belowmore » a critical height of ~10 nm. The divergence may be due to bending strain, which is treated only approximately in the model. Strong support for the CE model and its interpretation is provided by additional data for embedded Fe clusters. As a result most of these observations and insights should be generally applicable to systems where a metal cluster is embedded beneath a layered material or supported membrane, provided that shape equilibration is possible.« less

Authors:
 [1]; ORCiD logo [2];  [1]; ORCiD logo [3];  [3]; ORCiD logo [3]; ORCiD logo [2]
  1. Mechanical and Industrial Engineering, Northeastern University, Boston, USA
  2. Ames Laboratory, Ames, USA, Department of Chemistry, Iowa State University
  3. Ames Laboratory, Ames, USA, Department of Physics and Astronomy, Iowa State University
Publication Date:
Research Org.:
Ames Lab., Ames, IA (United States); Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States). National Energy Research Scientific Computing Center (NERSC)
Sponsoring Org.:
USDOE; USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22). Materials Sciences & Engineering; USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22). Materials Sciences & Engineering Division
OSTI Identifier:
1501745
Alternate Identifier(s):
OSTI ID: 1502871; OSTI ID: 1542913
Report Number(s):
IS-J-9899
Journal ID: ISSN 2040-3364; NANOHL
Grant/Contract Number:  
AC02-05CH11231; AC02-07CH11358; 70NANB15H235
Resource Type:
Journal Article: Published Article
Journal Name:
Nanoscale
Additional Journal Information:
Journal Name: Nanoscale Journal Volume: 11 Journal Issue: 13; Journal ID: ISSN 2040-3364
Publisher:
Royal Society of Chemistry (RSC)
Country of Publication:
United Kingdom
Language:
English
Subject:
77 NANOSCIENCE AND NANOTECHNOLOGY; 36 MATERIALS SCIENCE

Citation Formats

Julien, Scott E., Lii-Rosales, Ann, Wan, Kai-Tak, Han, Yong, Tringides, Michael C., Evans, James W., and Thiel, Patricia A.. Squeezed nanocrystals: equilibrium configuration of metal clusters embedded beneath the surface of a layered material. United Kingdom: N. p., 2019. Web. doi:10.1039/C8NR10549A.
Julien, Scott E., Lii-Rosales, Ann, Wan, Kai-Tak, Han, Yong, Tringides, Michael C., Evans, James W., & Thiel, Patricia A.. Squeezed nanocrystals: equilibrium configuration of metal clusters embedded beneath the surface of a layered material. United Kingdom. https://doi.org/10.1039/C8NR10549A
Julien, Scott E., Lii-Rosales, Ann, Wan, Kai-Tak, Han, Yong, Tringides, Michael C., Evans, James W., and Thiel, Patricia A.. Thu . "Squeezed nanocrystals: equilibrium configuration of metal clusters embedded beneath the surface of a layered material". United Kingdom. https://doi.org/10.1039/C8NR10549A.
@article{osti_1501745,
title = {Squeezed nanocrystals: equilibrium configuration of metal clusters embedded beneath the surface of a layered material},
author = {Julien, Scott E. and Lii-Rosales, Ann and Wan, Kai-Tak and Han, Yong and Tringides, Michael C. and Evans, James W. and Thiel, Patricia A.},
abstractNote = {Shapes of functional metallic nanocrystals, typically synthesized either free in solution or supported on surfaces, are key for controlling properties. Here, we consider a novel new class of metallic nanocrystals, copper clusters embedded near the surface of graphite, which can be considered a model system for metals embedded beneath surfaces of layered materials, or beneath supported membranes. We develop a continuum elasticity (CE) model for the equilibrium shape of these islands, and compare its predictions with experimental data. The CE model incorporates appropriate surface energy, adhesion energies, and strain energy. The agreement between the CE model and the data is—with one exception—excellent, both qualitatively and quantitatively, and is achieved with a single adjustable parameter. The model predicts that the embedded island shape is invariant with size, manifest both by constant side slope and by constant aspect ratio. This prediction is rationalized by dimensional analysis of the relevant energetic contributions. The aspect ratio (width : height) of an embedded Cu cluster is much larger than that of a supported but non-embedded Cu cluster, due to resistance of the graphene membrane to deformation. Experimental data diverge from the model predictions only in the case of the aspect ratio of small islands, below a critical height of ~10 nm. The divergence may be due to bending strain, which is treated only approximately in the model. Strong support for the CE model and its interpretation is provided by additional data for embedded Fe clusters. As a result most of these observations and insights should be generally applicable to systems where a metal cluster is embedded beneath a layered material or supported membrane, provided that shape equilibration is possible.},
doi = {10.1039/C8NR10549A},
url = {https://www.osti.gov/biblio/1501745}, journal = {Nanoscale},
issn = {2040-3364},
number = 13,
volume = 11,
place = {United Kingdom},
year = {2019},
month = {3}
}

Journal Article:
Free Publicly Available Full Text
Publisher's Version of Record at https://doi.org/10.1039/C8NR10549A

Citation Metrics:
Cited by: 1 work
Citation information provided by
Web of Science

Figures / Tables:

Fig. 1 Fig. 1: (a) STM image of a representative Cu cluster encapsulated beneath the graphite surface. The image has been derivatized to reveal edges more clearly. The inset shows a topographic version. (a$$^\prime$$) Line profile (with common X- and Z-axis scales) of the Cu island, corresponding to the white horizontal arrowmore » in (a). (b) Schematic diagram of the SLBT model and island dimensions. The inset shows a 3D representation of the model. (c) h vs. a for 140 Cu islands. (d) d vs. h for 140 Cu islands.« less

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Works referenced in this record:

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    Works referencing / citing this record:

    Shapes of Fe nanocrystals encapsulated at the graphite surface
    journal, February 2020


      Figures/Tables have been extracted from DOE-funded journal article accepted manuscripts.