Explosive-induced shock damage in copper and recompression of the damaged region
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36 MATERIALS SCIENCE↗
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Role of the interface on radiation damage in the SrTiO{sub 3}/LaAlO{sub 3} heterostructure under Ne{sup 2+} ion irradiation
We systematically investigated the microstructural evolution of heteroepitaxial SrTiO{sub 3} (STO) thin films grown on a single crystal LaAlO{sub 3} (LAO) (001) substrate, focusing on the response of the STO/LAO interface to Ne{sup 2+} irradiation at room temperature. Cross sectional transmission electron microscope (TEM) analysis reveals that the LAO crystal amorphizes first after a relatively low dose of damage followed by the amorphization of the STO film after irradiation to a higher dose. While the critical dose to amorphize differs between each material, amorphization begins at the interface and proceeds outward in both cases. Thus, a crystalline/amorphous interface first forms at the STO/LAO interface by a dose of 1 dpa, and then an amorphous/amorphous interface forms when the dose reaches 3 dpa. Scanning TEM and x-ray energy dispersive spectroscopy indicate no significant heavy cation elemental diffusion, though electron energy loss spectroscopy reveals a redistribution of oxygen across the film/substrate interface after Ne{sup 2+} irradiation. Atomistic calculations are used to interpret the experimental findings in terms of the defect properties in each of the two component phases.
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
High-energy radiation damage in zirconia: Modeling results
Zirconia is viewed as a material of exceptional resistance to amorphization by radiation damage, and consequently proposed as a candidate to immobilize nuclear waste and serve as an inert nuclear fuel matrix. Here, we perform molecular dynamics simulations of radiation damage in zirconia in the range of 0.1–0.5 MeV energies with account of electronic energy losses. We find that the lack of amorphizability co-exists with a large number of point defects and their clusters. These, importantly, are largely isolated from each other and therefore represent a dilute damage that does not result in the loss of long-range structural coherence and amorphization. We document the nature of these defects in detail, including their sizes, distribution, and morphology, and discuss practical implications of using zirconia in intense radiation environments.
36 MATERIALS SCIENCE↗
Impact of different cleaning processes on the laser damage threshold of antireflection coatings for Z-Backlighter optics at Sandia National Laboratories
We have examined how different cleaning processes affect the laser-induced damage threshold of antireflection coatings for large dimension, Z-Backlighter laser optics at Sandia National Laboratories. Laser damage thresholds were measured after the coatings were created, and again 4 months later to determine which cleaning processes were most effective. There is a nearly twofold increase in laser-induced damage threshold between the antireflection coatings that were cleaned and those that were not cleaned. Aging of the coatings after 4 months resulted in even higher laser-induced damage thresholds. Also, the laser-induced damage threshold results revealed that every antireflection coating had a high defect density, despite the cleaning process used, which indicates that improvements to either the cleaning or deposition processes should provide even higher laser-induced damage thresholds.
36 MATERIALS SCIENCE↗
Self-Irradiation Damage to the Local Structure of Plutonium and Plutonium Intermetallics
Abstract Not Provided
XFEL, PHYS↗
The impact of contamination and aging effects on the long-term laser-damage resistance of SiO 2 /HfO 2 /TiO 2 high-reflection coatings for 1054nm
The laser damage thresholds of optical coatings can degrade over time due to a variety of factors, including contamination and aging. Optical coatings deposited using electron beam evaporation are particularly susceptible to degradation due to their porous structure. In a previous study, the laser damage thresholds of optical coatings were reduced by roughly a factor of two from 2013 to 2017. The coatings in question were high reflectors for 1054 nm that contained SiO 2 and HfO 2 and/or TiO 2 layers, and they were stored in sealed PETG containers in a class 100 cleanroom with temperature control. At the time, it was not certain whether contamination or thin film aging effects were responsible for the reduced laser damage thresholds. Therefore, to better understand the role of contamination, the coatings were recleaned and the laser damage thresholds were measured again in 2018. Here, the results indicate that contamination played the most dominant role in reducing the laser damage thresholds of these optical coatings, even though they were stored in an environment that was presumed to be clean.
42 ENGINEERING↗
Characterization of swift heavy ion irradiation damage in ceria
We have examined microstructural evolution in irradiated ceria (CeO2) using swift heavy ion irradiation, electron microscopy, and atomistic simulation. CeO2, a UO2 fuel surrogate, was irradiated with gold ions at an energy of 1 GeV to fluences up to 1x1014 ions/cm2. Transmission electron microscopy accompanied by electron energy loss spectroscopy showed that the ion tracks were of similar size at all fluences, and that there was no chemical change in the ion track core. Classical molecular dynamics simulations of thermal spikes in CeO2 with energy deposition of 12 and 36 keV/nm show damage consisting of isolated point defects at the lower energy and defect clusters at 36 keV/nm, with no amorphization at either energy. Inferences are drawn from modeling about density changes in the ion track and the formation of interstitial loops that shed light on features observed by electron microscopy of swift heavy ion irradiated ceria.
Yablinsky, Clarissa↗
Numerical study of damage in particulate composites during high-strain rate loading using novel damage model
Not provided.
Materials Science↗
Test simulation of neutron damage to electronic components using accelerator facilities
Not Available
King, D. B.↗
Cationic Dependence of X-ray Induced Damage in Strontium and Barium Nitrate
The response of solids to x-ray irradiation is not well understood, in part, because the interactions between x-rays and molecules in solids depend on the intra- and/or inter-molecular electronic properties of the material. Our previous work demonstrated that x-ray induced damage of certain ionic salts depends on the irradiating photon energy, especially when irradiated with photons of energy near the cation’s K-edge. To advance understanding of the cationic dependence of x-ray photochemistry, we present studies of x-ray induced damage of barium nitrate and strontium nitrate. Polycrystalline samples of barium and strontium nitrate were irradiated with high flux monochromatic synchrotron x-rays at selected energies near the K-edge of the respective cations. The damage processes were studied with powder x-ray diffraction, and irradiation products, NO 2 and O 2 , were characterized via Raman spectroscopy. Our results demonstrate that irradiating barium and strontium nitrate with photons of energy greater than the K-edge of the cation promotes high rate of decomposition compared to that observed when irradiating with photons of energy below the K-edge. Additionally, differences in x-ray induced damage between the two compounds are examined and discussed, and evidence of the diffusion of irradiation products is presented.
36 MATERIALS SCIENCE↗
High-pressure-assisted X-ray-induced damage as a new route for chemical and structural synthesis
A novel structural and chemical synthesis of Cs–O derived materials has been demonstrated via X-ray irradiation of Cs 2 C 2 H 2 O 5 at high pressure.
Evlyukhin, Egor↗
Optimization of a low noise detection circuit for probing the structure of damage cascades with IBIC
Optimal detector / pre-amplifier combinations have been identified for the use of light ion IBIC (ion beam induced charge) to probe the physical structure of electrically active defects in damage cascades caused by heavy ion implantation. The ideal detector must have a sufficiently thin dead layer that incident ions will produce the majority of damage cascades in the depletion region of the detector rather than the dead layer. Detector and circuit noise must be low enough to detect the implantation of a single heavy ion as well as the decrease in the light ion IBIC signal caused by Shockley-Read-Hall recombination when the beam scans regions of the detector damaged by the heavy ion. The IBIC signals from three detectors irradiated with 750 keV He⁺ ions are measured with commercial and bespoke charge sensitive pre-amplifiers to identify the combination with the lowest noise.
46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
Radiation damage in heteroepitaxial BaTiO{sub 3} thin films on SrTiO{sub 3} under Ne ion irradiation
The microstructure evolution of heteroepitaxial BaTiO{sub 3} (BTO) thin films grown on single crystal (001) SrTiO{sub 3} (STO) under Ne irradiation at room temperature was systematically investigated with special attention given to the behavior at the BTO/STO interface. Cross sectional transmission electron microscope investigations reveal that amorphization occurs at the top BTO film region. BTO grains in the dimensions of 10-20 nm survived the irradiation damage and maintained their original crystal orientation. Other irradiation-induced defects such as dislocation loops and defect clusters were observed only at the portion of the BTO thin film near the interface, but not at the STO side of the bilayer. Atomic calculations find that the energetics of defects are very similar on each side of the BTO/STO interface, suggesting that the interface will not significantly modify radiation damage evolution in this system, in agreement with the experimental observations. These results support the hypothesis we presented in previous work about the role of coherent interfaces on radiation damage evolution.
36 MATERIALS SCIENCE↗
Repair of a mirror coating on a large optic for high laser damage applications using ion milling and over-coating methods
Here, when an optical coating is damaged, deposited incorrectly, or is otherwise unsuitable, the conventional method to restore the optic often entails repolishing the optic surface, which can incur a large cost and long lead time. We propose three alternative options to repolishing, including (i) burying the unsuitable coating under another optical coating, (ii) using ion milling to etch the unsuitable coating completely from the optic surface and then recoating the optic, and (iii) using ion milling to etch through a number of unsuitable layers, leaving the rest of the coating intact, and then recoating the layers that were etched. Repairs were made on test optics with dielectric mirror coatings according to the above three options. The mirror coatings to be repaired were quarter wave stacks of HfO 2 and SiO 2 layers for high reflection at 1054 nm at 45 deg incidence in P-polarization. One of the coating layers was purposely deposited incorrectly as Hf metal instead of HfO2 to evaluate the ability of each repair method to restore the coating’s high laser-induced damage threshold (LIDT) of 64.0 J/cm 2 . The repaired coating with the highest resistance to laser-induced damage was achieved using repair method (ii) with an LIDT of 49.0 to 61.0 J/cm 2 .
36 MATERIALS SCIENCE↗
Characterization of irradiation damage distribution near TiO{sub 2}/SrTiO{sub 3} interfaces using coherent acoustic phonon interferometry
We apply ultrafast coherent acoustic phonon interferometry to characterize the distribution of the radiation damage near the TiO{sub 2}/SrTiO{sub 3} interfaces. We show that the optical and mechanical properties of anatase TiO{sub 2} remain unaffected by the radiation dosages in the 0.1 Division-Sign 5 dpa (displacements per atom) range, while the degraded optical response indicates a significant defect accumulation in the interfacial region of SrTiO{sub 3} at 0.1 dpa and subsequent amorphization at 3 dpa. Comparison between the theoretical simulations and the experimental results reveals an almost threefold reduction of the sound velocity in the irradiated SrTiO{sub 3} layer with peak damage levels of 3 and 5 dpa.
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
Defect interactions with stepped CeO{sub 2}/SrTiO{sub 3} interfaces: Implications for radiation damage evolution and fast ion conduction
Due to reduced dimensions and increased interfacial content, nanocomposite oxides offer improved functionalities in a wide variety of advanced technological applications, including their potential use as radiation tolerant materials. To better understand the role of interface structures in influencing the radiation damage tolerance of oxides, we have conducted atomistic calculations to elucidate the behavior of radiation-induced point defects (vacancies and interstitials) at interface steps in a model CeO{sub 2}/SrTiO{sub 3} system. We find that atomic-scale steps at the interface have substantial influence on the defect behavior, which ultimately dictate the material performance in hostile irradiation environments. Distinctive steps react dissimilarly to cation and anion defects, effectively becoming biased sinks for different types of defects. Steps also attract cation interstitials, leaving behind an excess of immobile vacancies. Further, defects introduce significant structural and chemical distortions primarily at the steps. These two factors are plausible origins for the enhanced amorphization at steps seen in our recent experiments. The present work indicates that comprehensive examination of the interaction of radiation-induced point defects with the atomic-scale topology and defect structure of heterointerfaces is essential to evaluate the radiation tolerance of nanocomposites. Finally, our results have implications for other applications, such as fast ion conduction.
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
Metabolite Damage and Metabolite Damage Control in Plants
It is increasingly clear that (a) many metabolites undergo spontaneous or enzyme-catalyzed side reactions in vivo, (b) the damaged metabolites formed by these reactions can be harmful, and (c) organisms have biochemical systems that limit the buildup of damaged metabolites. These damage-control systems either return a damaged molecule to its pristine state (metabolite repair) or convert harmful molecules to harmless ones (damage preemption). Because all organisms share a core set of metabolites that suffer the same chemical and enzymatic damage reactions, certain damage-control systems are widely conserved across the kingdoms of life. Relatively few damage reactions and damage-control systems are well known. Uncovering new damage reactions and identifying the corresponding damaged metabolites, damage-control genes, and enzymes demands a coordinated mix of chemistry, metabolomics, cheminformatics, biochemistry, and comparative genomics. This review illustrates the above points using examples from plants, which are at least as prone to metabolite damage as other organisms.
cheminformatics↗