A descriptive model linking possible formation mechanisms for graphite-encapsulated nanocrystals to processing parameters

B. R. Elliott; J. J. Host; V. P. Dravid; M. H. Teng; J. H. Hwang

doi:10.1557/JMR.1997.0438

A descriptive model linking possible formation mechanisms for graphite-encapsulated nanocrystals to processing parameters

B. R. Elliott, J. J. Host, V. P. Dravid^*, M. H. Teng, J. H. Hwang

^*Corresponding author for this work

Materials Science and Engineering

Research output: Contribution to journal › Article › peer-review

78 Scopus citations

Abstract

New and modified mechanisms are proposed to account for detailed observations of carbon encapsulation of Fe, Ni, and Co nanocrysials. The mechanisms are based on aerosol and gas phase chemistry and on the catalytic effects of transition metals. Two parameters are found to qualitatively dominate production: the local-path carbon-to-metal ratio (LCM) and the global carbon-to-metal ratio (GCM). LCM's select which mechanisms are active along each pathway within the reactor. The GCM places bounds upon and determines the weighting between different LCM's and thus determines the distribution of different nanoscale products within the collected, macroscopic product. A two part processing parameter → mechanism → product map links the components. The generality of the model is discussed throughout with reference to related processes and the encapsulation of other materials.

Original language	English (US)
Pages (from-to)	3328-3344
Number of pages	17
Journal	Journal of Materials Research
Volume	12
Issue number	12
DOIs	https://doi.org/10.1557/JMR.1997.0438
State	Published - Dec 1997

Funding

The authors would like to thank a number of people for their extensive support. D. Lynn Johnson was invaluable in process design and optimization. Julia R. Weertman provided extensive editorial comment and many scientific challenges. Her questions often drove us to new insights and new experiments. We also appreciate receiving a number of early preprints from Supapan Seraphin. Deb Serra, Mary Girard, and Mark Lowe aided in some of the experiments. Financial support for this work was provided by the Materials Research Center (MRC) of Northwestern University via DMR-9120521 and by the National Science Foundation (NSF) through DMR-9202574 and its NYI award program via DMR-9357513.

ASJC Scopus subject areas

General Materials Science
Condensed Matter Physics
Mechanics of Materials
Mechanical Engineering

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title = "A descriptive model linking possible formation mechanisms for graphite-encapsulated nanocrystals to processing parameters",

abstract = "New and modified mechanisms are proposed to account for detailed observations of carbon encapsulation of Fe, Ni, and Co nanocrysials. The mechanisms are based on aerosol and gas phase chemistry and on the catalytic effects of transition metals. Two parameters are found to qualitatively dominate production: the local-path carbon-to-metal ratio (LCM) and the global carbon-to-metal ratio (GCM). LCM's select which mechanisms are active along each pathway within the reactor. The GCM places bounds upon and determines the weighting between different LCM's and thus determines the distribution of different nanoscale products within the collected, macroscopic product. A two part processing parameter → mechanism → product map links the components. The generality of the model is discussed throughout with reference to related processes and the encapsulation of other materials.",

author = "Elliott, {B. R.} and Host, {J. J.} and Dravid, {V. P.} and Teng, {M. H.} and Hwang, {J. H.}",

note = "Funding Information: The authors would like to thank a number of people for their extensive support. D. Lynn Johnson was invaluable in process design and optimization. Julia R. Weertman provided extensive editorial comment and many scientific challenges. Her questions often drove us to new insights and new experiments. We also appreciate receiving a number of early preprints from Supapan Seraphin. Deb Serra, Mary Girard, and Mark Lowe aided in some of the experiments. Financial support for this work was provided by the Materials Research Center (MRC) of Northwestern University via DMR-9120521 and by the National Science Foundation (NSF) through DMR-9202574 and its NYI award program via DMR-9357513.",

year = "1997",

month = dec,

doi = "10.1557/JMR.1997.0438",

language = "English (US)",

volume = "12",

pages = "3328--3344",

journal = "Journal of Materials Research",

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AU - Host, J. J.

AU - Dravid, V. P.

AU - Teng, M. H.

AU - Hwang, J. H.

N1 - Funding Information: The authors would like to thank a number of people for their extensive support. D. Lynn Johnson was invaluable in process design and optimization. Julia R. Weertman provided extensive editorial comment and many scientific challenges. Her questions often drove us to new insights and new experiments. We also appreciate receiving a number of early preprints from Supapan Seraphin. Deb Serra, Mary Girard, and Mark Lowe aided in some of the experiments. Financial support for this work was provided by the Materials Research Center (MRC) of Northwestern University via DMR-9120521 and by the National Science Foundation (NSF) through DMR-9202574 and its NYI award program via DMR-9357513.

PY - 1997/12

Y1 - 1997/12

N2 - New and modified mechanisms are proposed to account for detailed observations of carbon encapsulation of Fe, Ni, and Co nanocrysials. The mechanisms are based on aerosol and gas phase chemistry and on the catalytic effects of transition metals. Two parameters are found to qualitatively dominate production: the local-path carbon-to-metal ratio (LCM) and the global carbon-to-metal ratio (GCM). LCM's select which mechanisms are active along each pathway within the reactor. The GCM places bounds upon and determines the weighting between different LCM's and thus determines the distribution of different nanoscale products within the collected, macroscopic product. A two part processing parameter → mechanism → product map links the components. The generality of the model is discussed throughout with reference to related processes and the encapsulation of other materials.

AB - New and modified mechanisms are proposed to account for detailed observations of carbon encapsulation of Fe, Ni, and Co nanocrysials. The mechanisms are based on aerosol and gas phase chemistry and on the catalytic effects of transition metals. Two parameters are found to qualitatively dominate production: the local-path carbon-to-metal ratio (LCM) and the global carbon-to-metal ratio (GCM). LCM's select which mechanisms are active along each pathway within the reactor. The GCM places bounds upon and determines the weighting between different LCM's and thus determines the distribution of different nanoscale products within the collected, macroscopic product. A two part processing parameter → mechanism → product map links the components. The generality of the model is discussed throughout with reference to related processes and the encapsulation of other materials.

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A descriptive model linking possible formation mechanisms for graphite-encapsulated nanocrystals to processing parameters

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