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Title: Effects of two-temperature model on cascade evolution in Ni and NiFe

Abstract

We perform molecular dynamics simulations of Ni ion cascades in Ni and equiatomic NiFe under the following conditions: (a) classical molecular dynamics (MD) simulations without consideration of electronic energy loss, (b) classical MD simulations with the electronic stopping included, and (c) using the coupled two-temperature MD (2T-MD) model that incorporates both the electronic stopping and the electron-phonon interactions. Our results indicate that the electronic effects are more profound in the higher-energy cascades, and that the 2T-MD model results in a smaller amount of surviving damage and smaller defect clusters, while less damage is produced in NiFe than in Ni.

Authors:
 [1];  [2];  [1];  [1]
  1. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
  2. Univ. of Tennessee, Knoxville, TN (United States)
Publication Date:
Research Org.:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Sponsoring Org.:
USDOE Office of Science (SC)
OSTI Identifier:
1261385
Grant/Contract Number:
AC05-00OR22725
Resource Type:
Journal Article: Accepted Manuscript
Journal Name:
Scripta Materialia
Additional Journal Information:
Journal Volume: 124; Journal ID: ISSN 1359-6462
Publisher:
Elsevier
Country of Publication:
United States
Language:
English
Subject:
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; Two-Temperature Model; Ni; NiFe; Radiation Damage; Cascades

Citation Formats

Samolyuk, German D., Xue, Haizhou, Bei, Hongbin, and Weber, William J.. Effects of two-temperature model on cascade evolution in Ni and NiFe. United States: N. p., 2016. Web. doi:10.1016/j.scriptamat.2016.06.028.
Samolyuk, German D., Xue, Haizhou, Bei, Hongbin, & Weber, William J.. Effects of two-temperature model on cascade evolution in Ni and NiFe. United States. doi:10.1016/j.scriptamat.2016.06.028.
Samolyuk, German D., Xue, Haizhou, Bei, Hongbin, and Weber, William J.. 2016. "Effects of two-temperature model on cascade evolution in Ni and NiFe". United States. doi:10.1016/j.scriptamat.2016.06.028. https://www.osti.gov/servlets/purl/1261385.
@article{osti_1261385,
title = {Effects of two-temperature model on cascade evolution in Ni and NiFe},
author = {Samolyuk, German D. and Xue, Haizhou and Bei, Hongbin and Weber, William J.},
abstractNote = {We perform molecular dynamics simulations of Ni ion cascades in Ni and equiatomic NiFe under the following conditions: (a) classical molecular dynamics (MD) simulations without consideration of electronic energy loss, (b) classical MD simulations with the electronic stopping included, and (c) using the coupled two-temperature MD (2T-MD) model that incorporates both the electronic stopping and the electron-phonon interactions. Our results indicate that the electronic effects are more profound in the higher-energy cascades, and that the 2T-MD model results in a smaller amount of surviving damage and smaller defect clusters, while less damage is produced in NiFe than in Ni.},
doi = {10.1016/j.scriptamat.2016.06.028},
journal = {Scripta Materialia},
number = ,
volume = 124,
place = {United States},
year = 2016,
month = 7
}

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  • Oxygen evolution reaction (OER) plays a crucial role in various energy conversion devices such as water electrolyzers and metal–air batteries. Precious metal catalysts such as Ir, Ru and their oxides are usually used for enhancing reaction kinetics but are limited by their scarcity. The challenges associated with alternative non–precious metal catalysts such as transition metal oxides and (oxy)hydroxides are their low electronic conductivity and durability. The carbon encapsulating transition metal nanoparticles are expected to address these challenges. However, the relationship between precursor compositions and catalyst properties, and the intrinsic functions of each component has been rarely studied. In this paper,more » we report a highly durable (no degradation after 20,000 cycles) and highly active (360 mV overpotential at 10 mA cm –2 GEO) OER catalyst derived from bimetallic metal–organic frameworks (MOFs) precursors. This catalyst consists of NiFe nanoparticles encapsulated by nitrogen–doped graphitized carbon shells. The electron–donation/deviation from Fe and tuned lattice and electronic structures of metal cores by Ni are revealed to be primary contributors to the enhanced OER activity, whereas N concentration contributes negligibly. Finally, we further demonstrated that the structure and morphology of encapsulating carbon shells, which are the key factors influencing the durability, are facilely controlled by the chemical state of precursors.« less
  • Oxygen evolution reaction (OER) plays a crucial role in various energy conversion devices such as water electrolyzers and metal–air batteries. Precious metal catalysts such as Ir, Ru and their oxides are usually used for enhanced reaction kinetics but are limited by their scarce resource. The challenges associated with alternative non–precious metal catalysts such as transition metal oxides and (oxy)hydroxides etc. are their low electronic conductivity and poor durability. Here, we report OER catalysts of NiFe nanoparticles encapsulated by nitrogen–doped graphitized carbon shells derived from bimetallic metal–organic frameworks (MOFs) precursors. The optimal OER catalyst shows excellent activity (360 mV overpotential atmore » 10 mA cm–2GEO) and durability (no obvious degradation after 20 000 cycles). The electron-donation from Fe and tuned electronic structure of metal cores by Ni are revealed to be primary contributors to the enhanced OER activity. We further demonstrated that the structure and morphology of encapsulating carbon shells, which are the key factors influencing the durability, are facilely controlled by chemical state of precursors. Severe metal particle growth probably caused by oxidation of carbon shells and encapsulated nanoparticles is believed to the main mechanism for activity degradation in these catalysts.« less
  • Oxygen evolution reaction (OER) plays a crucial role in various energy conversion devices such as water electrolyzers and metal–air batteries. Precious metal catalysts such as Ir, Ru and their oxides are usually used for enhancing reaction kinetics but are limited by their scarce resource. The challenges associated with alternative non–precious metal catalysts such as transition metal oxides and (oxy)hydroxides etc. are their low electronic conductivity and durability. Herein, we report a highly active (360 mV overpotential at 10 mA cm–2GEO) and durable (no degradation after 20000 cycles) OER catalyst derived from bimetallic metal–organic frameworks (MOFs) precursors. This catalyst consists ofmore » NiFe nanoparticles encapsulated by nitrogen–doped graphitized carbon shells. The electron-donation/deviation from Fe and tuned electronic structure of metal cores by Ni are revealed to be primary contributors to the enhanced OER activity, whereas N concentration contributes negligibly. We further demonstrated that the structure and morphology of encapsulating carbon shells, which are the key factors influencing the durability, are facilely controlled by the chemical state of precursors.« less