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Title: Enthalpy Landscape Dictates the Irradiation-Induced Disordering of Quartz

Abstract

Here, under irradiation, minerals tend to experience an accumulation of structural defects, ultimately leading to a disordered atomic network. Despite the critical importance of understanding and predicting irradiation-induced damage, the physical origin of the initiation and saturation of defects remains poorly understood. Here, based on molecular dynamics simulations of α-quartz, we show that the topography of the enthalpy landscape governs irradiation-induced disordering. Specifically, we show that such disordering differs from that observed upon vitrification in that, prior to saturation, irradiated quartz accesses forbidden regions of the enthalpy landscape, i.e., those that are inaccessible by simply heating and cooling. Furthermore, we demonstrate that damage saturates when the system accesses a local region of the enthalpy landscape corresponding to the configuration of an allowable liquid. At this stage, a sudden decrease in the heights of the energy barriers enhances relaxation, thereby preventing any further accumulation of defects and resulting in a defect-saturated disordered state.

Authors:
 [1];  [1];  [1]; ORCiD logo [2];  [1];  [1]
  1. Univ. of California, Los Angeles, CA (United States)
  2. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Publication Date:
Research Org.:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Sponsoring Org.:
USDOE
OSTI Identifier:
1373316
Grant/Contract Number:
AC05-00OR22725; 4000132990; 4000143356
Resource Type:
Journal Article: Published Article
Journal Name:
Physical Review. X
Additional Journal Information:
Journal Volume: 7; Journal Issue: 3; Journal ID: ISSN 2160-3308
Publisher:
American Physical Society
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE

Citation Formats

Krishnan, N. M. Anoop, Wang, Bu, Yu, Yingtian, Le Pape, Yann, Sant, Gaurav, and Bauchy, Mathieu. Enthalpy Landscape Dictates the Irradiation-Induced Disordering of Quartz. United States: N. p., 2017. Web. doi:10.1103/PhysRevX.7.031019.
Krishnan, N. M. Anoop, Wang, Bu, Yu, Yingtian, Le Pape, Yann, Sant, Gaurav, & Bauchy, Mathieu. Enthalpy Landscape Dictates the Irradiation-Induced Disordering of Quartz. United States. doi:10.1103/PhysRevX.7.031019.
Krishnan, N. M. Anoop, Wang, Bu, Yu, Yingtian, Le Pape, Yann, Sant, Gaurav, and Bauchy, Mathieu. 2017. "Enthalpy Landscape Dictates the Irradiation-Induced Disordering of Quartz". United States. doi:10.1103/PhysRevX.7.031019.
@article{osti_1373316,
title = {Enthalpy Landscape Dictates the Irradiation-Induced Disordering of Quartz},
author = {Krishnan, N. M. Anoop and Wang, Bu and Yu, Yingtian and Le Pape, Yann and Sant, Gaurav and Bauchy, Mathieu},
abstractNote = {Here, under irradiation, minerals tend to experience an accumulation of structural defects, ultimately leading to a disordered atomic network. Despite the critical importance of understanding and predicting irradiation-induced damage, the physical origin of the initiation and saturation of defects remains poorly understood. Here, based on molecular dynamics simulations of α-quartz, we show that the topography of the enthalpy landscape governs irradiation-induced disordering. Specifically, we show that such disordering differs from that observed upon vitrification in that, prior to saturation, irradiated quartz accesses forbidden regions of the enthalpy landscape, i.e., those that are inaccessible by simply heating and cooling. Furthermore, we demonstrate that damage saturates when the system accesses a local region of the enthalpy landscape corresponding to the configuration of an allowable liquid. At this stage, a sudden decrease in the heights of the energy barriers enhances relaxation, thereby preventing any further accumulation of defects and resulting in a defect-saturated disordered state.},
doi = {10.1103/PhysRevX.7.031019},
journal = {Physical Review. X},
number = 3,
volume = 7,
place = {United States},
year = 2017,
month = 7
}

Journal Article:
Free Publicly Available Full Text
Publisher's Version of Record at 10.1103/PhysRevX.7.031019

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  • Here, under irradiation, minerals tend to experience an accumulation of structural defects, ultimately leading to a disordered atomic network. Despite the critical importance of understanding and predicting irradiation-induced damage, the physical origin of the initiation and saturation of defects remains poorly understood. Here, based on molecular dynamics simulations of α-quartz, we show that the topography of the enthalpy landscape governs irradiation-induced disordering. Specifically, we show that such disordering differs from that observed upon vitrification in that, prior to saturation, irradiated quartz accesses forbidden regions of the enthalpy landscape, i.e., those that are inaccessible by simply heating and cooling. Furthermore, wemore » demonstrate that damage saturates when the system accesses a local region of the enthalpy landscape corresponding to the configuration of an allowable liquid. At this stage, a sudden decrease in the heights of the energy barriers enhances relaxation, thereby preventing any further accumulation of defects and resulting in a defect-saturated disordered state.« less
  • The intermetallic compounds NiTi, NiTi/sub 2/, CuZr, CuTi/sub 2/, and Zr/sub 3/Al were irradiated by 2 MeV protons at various temperatures between --175 /degree/C and --44 /degree/C to a fluence of 1.9/times/10/sup 22/ H/sup +//m/sup 2/. Transmission electron microscopy, electron diffraction, and x-ray diffraction were used to evaluate the extents of disordering and amorphization induced by irradiation in the samples. Both phenomena progressed to varying extents in the five compounds, depending on the irradiation temperature and dose. It was observed that the C-A transition began before the degree of long-range order was reduced significantly, and that the amorphous phase nucleatedmore » homogeneously throughout the crystalline matrix. A major finding of the current investigation is that the technique of scanning electron fractography provides a useful correlation between the features of the fractured surfaces and the microstructural alterations induced by the proton irradiations. When amorphization is complete the fracture surfaces are either featureless (e.g., NiTi/sub 2/) or contain branching features resembling river patterns. In some cases (especially in CuZr) these are similar to the markings seen on the surface of fractured amorphous ribbons produced by melt-spinning. In general, however, there is not a particularly good correlation between the features on the fracture surfaces of the irradiated and melt-spun ribbons. When the microstructure consists of amorphous regions embedded in a partially disordered crystalline matrix, there is consierable evidence for irradiation-induced ductility. In such cases, exemplified by the results on NiTi and Zr/sub 3/Al, the fracture surfaces contain dimples, characteristic of ductile fracture, suggesting that disordering promotes ductility.« less
  • KAP1 recruits many proteins involved in gene silencing and functions as an integral part of co-repressor complex. KAP1 was identified as Mdm2-binding protein and shown to form a complex with Mdm2 and p53 in vivo. We examined the role of KAP1 in p53 activation after the treatment of cells with different types of external stresses. KAP1 reduction markedly enhanced the induction of p21, a product of the p53 target gene, after treatment with actinomycin D or {gamma}-irradiation, but not with camptothecin. Treatment with actinomycin D, but not with camptothecin, augmented the interaction of p53 with Mdm2 and KAP1. Further, KAP1more » reduction in actinomycin D-treated cells facilitated cell cycle arrest and negatively affected clonal cell growth. Thus, the reduction of KAP1 levels promotes p53-dependent p21 induction and inhibits cell proliferation in actinomycin D-treated cells. KAP1 may serve as a therapeutic target against cancer in combination with actinomycin D.« less