Vacancy-driven variations in the phonon density of states of fast neutron irradiated nuclear graphite

Iyad I. Al-Qasir; Anne A. Campbell; Gabriele Sala; Jiao Y.Y. Lin; Yongqiang Cheng; Fahima F. Islam; Douglas L. Abernathy; Matthew B. Stone

doi:10.1016/j.carbon.2020.05.027

Vacancy-driven variations in the phonon density of states of fast neutron irradiated nuclear graphite

Iyad I. Al-Qasir, Anne A. Campbell, Gabriele Sala, Jiao Y.Y. Lin, Yongqiang Cheng, Fahima F. Islam, Douglas L. Abernathy, Matthew B. Stone

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

14 Scopus citations

Abstract

Research examining radiation damage and its effects in graphite began in the 1940’s during the development of moderated nuclear reactors. Interest in this topic is expanding because of emerging applications associated with fullerenes and carbon nanostructures as well as its long-standing use as a fission moderator. In this work, we report the measurements of the full phonon density of states of irradiated nuclear graphite using inelastic neutron scattering experiments at room temperature. The samples were previously exposed to different levels of neutron doses and irradiation temperatures. The phonon density of states of perfect and defected graphite supercells including different configurations of vacancies and interstitials were calculated using first-principles direct method. Despite high neutron irradiation doses, the scattering measurements show that the induced damage is localized, and the layered structure is preserved. A comparison of the measured phonon densities of states of irradiated samples with those calculated of defected supercells indicates that the main changes observed are mainly attributed to formation of vacancies.

Original language	English
Pages (from-to)	42-54
Number of pages	13
Journal	Carbon
Volume	168
DOIs	https://doi.org/10.1016/j.carbon.2020.05.027
State	Published - Oct 30 2020

Bibliographical note

Publisher Copyright:
© 2020 Elsevier Ltd

Funding

The irradiation of the specimens was performed at the Oak Ridge National Laboratory (ORNL) and sponsored by Tokai Carbon Co. Ltd. (NFE-09-02345) with the U.S. Department of Energy. A portion of this research at ORNL's High Flux Isotope Reactor and the Spallation Neutron Source was sponsored by the Scientific User Facilities Division, Office of Basic Energy Sciences, US Department of Energy. Oak Ridge National Laboratory is managed by UT-Battelle, LLC under Contract No. DE-AC05-00OR22725 for the U.S. Department of Energy. This material is based upon work that was conducted by I. I. Al-Qasir while a Visiting Research Fellow at the Shull Wollan Center—the University of Tennessee and Oak Ridge National Laboratory's Joint Institute for Neutron Sciences. The DFT simulations performed using the High-Performance Computing Facility (SAQR) at University of Sharjah. Special thanks to Ms. Naila Perveen from Center for Advanced Materials Research Center at the University of Sharjah for helping in simulation data manipulation. The irradiation of the specimens was performed at the Oak Ridge National Laboratory (ORNL) and sponsored by Tokai Carbon Co., Ltd. ( NFE-09-02345 ) with the U.S. Department of Energy. A portion of this research at ORNL’s High Flux Isotope Reactor and the Spallation Neutron Source was sponsored by the Scientific User Facilities Division, Office of Basic Energy Sciences, US Department of Energy. Oak Ridge National Laboratory is managed by UT-Battelle, LLC under Contract No. DE-AC05-00OR22725 for the U.S. Department of Energy. This material is based upon work that was conducted by I. I. Al-Qasir while a Visiting Research Fellow at the Shull Wollan Center—the University of Tennessee and Oak Ridge National Laboratory’s Joint Institute for Neutron Sciences. The DFT simulations performed using the High-Performance Computing Facility (SAQR) at University of Sharjah. Special thanks to Ms. Naila Perveen from Center for Advanced Materials Research Center at the University of Sharjah for helping in simulation data manipulation. This manuscript has been authored in part by UT-Battelle, LLC, under contract DE-AC05-00OR22725 with the US Department of Energy (DOE). The US government retains and the publisher, by accepting the article for publication, acknowledges that the US government retains a nonexclusive, paid-up, irrevocable, worldwide license to publish or reproduce the published form of this manuscript, or allow others to do so, for US government purposes. DOE will provide public access to these results of federally sponsored research in accordance with the DOE Public Access Plan ( http://energy.gov/downloads/doe-public-access-plan ).

Funders	Funder number
Center for Advanced Materials Research Center at the University of Sharjah
Joint Institute for Neutron Sciences
ORNL's High Flux Isotope Reactor
ORNL’s High Flux Isotope Reactor
Scientific User Facilities Division
Tokai Carbon Co. Ltd.	NFE-09-02345
U.S. Department of Energy
Basic Energy Sciences
Oak Ridge National Laboratory
University of Tennessee
University of Sharjah
UT-Battelle	DE-AC05-00OR22725

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title = "Vacancy-driven variations in the phonon density of states of fast neutron irradiated nuclear graphite",

abstract = "Research examining radiation damage and its effects in graphite began in the 1940{\textquoteright}s during the development of moderated nuclear reactors. Interest in this topic is expanding because of emerging applications associated with fullerenes and carbon nanostructures as well as its long-standing use as a fission moderator. In this work, we report the measurements of the full phonon density of states of irradiated nuclear graphite using inelastic neutron scattering experiments at room temperature. The samples were previously exposed to different levels of neutron doses and irradiation temperatures. The phonon density of states of perfect and defected graphite supercells including different configurations of vacancies and interstitials were calculated using first-principles direct method. Despite high neutron irradiation doses, the scattering measurements show that the induced damage is localized, and the layered structure is preserved. A comparison of the measured phonon densities of states of irradiated samples with those calculated of defected supercells indicates that the main changes observed are mainly attributed to formation of vacancies.",

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AU - Al-Qasir, Iyad I.

AU - Campbell, Anne A.

AU - Sala, Gabriele

AU - Lin, Jiao Y.Y.

AU - Cheng, Yongqiang

AU - Islam, Fahima F.

AU - Abernathy, Douglas L.

AU - Stone, Matthew B.

PY - 2020/10/30

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AB - Research examining radiation damage and its effects in graphite began in the 1940’s during the development of moderated nuclear reactors. Interest in this topic is expanding because of emerging applications associated with fullerenes and carbon nanostructures as well as its long-standing use as a fission moderator. In this work, we report the measurements of the full phonon density of states of irradiated nuclear graphite using inelastic neutron scattering experiments at room temperature. The samples were previously exposed to different levels of neutron doses and irradiation temperatures. The phonon density of states of perfect and defected graphite supercells including different configurations of vacancies and interstitials were calculated using first-principles direct method. Despite high neutron irradiation doses, the scattering measurements show that the induced damage is localized, and the layered structure is preserved. A comparison of the measured phonon densities of states of irradiated samples with those calculated of defected supercells indicates that the main changes observed are mainly attributed to formation of vacancies.

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Vacancy-driven variations in the phonon density of states of fast neutron irradiated nuclear graphite

Abstract

Bibliographical note

Funding

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