Papers by Keyword: Ion Irradiation

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Authors: Chong Hong Zhang, Yue Sheng Wang, K.Q. Chen, Ji Guo Sun, J.M. Quan, Chang Qi Chen
Abstract: Low-activation Fe-Cr-Mn alloy and 316L stainless steel were irradiated with 92 MeV Ar ions at about 500°C, to fluences of 0.8~1.7×1021 ions m-2 .After irradiation, cross-sectional specimens were investigated with transmission electron microscopy.Cavities with high number density were observed in the peak dose regions. The cavity number density reaches maximum at Ar concentration peak, while cavity mean size is consistent with displacement damage profile. It is indicated that Ar atoms can enhance cavity formation in a manner similar to helium. There are thresholds of dose and dose rate for the bi-modal size distribution of cavities. The significant growth of a small portion of cavities in the peak damage region at the highest ion-fluence is ascribed to the effect of interactive sink strength of cavities.
Authors: P.D. Edmondson, S.E. Donnelly, R.C. Birtcher
Abstract: In this paper we present a detailed study in which the formation, by heavy ion impact, and thermal recrystallisation of individual amorphous zones have been studied using in-situ transmission electron microscopy. In agreement with previous work, we observe a reduction in the total volume of amorphous material contained within the amorphous zones following thermal annealing over a wide range of temperatures. When the evolution of the individual amorphous zones is followed, those with similar starting sizes are observed to recrystallise over a range of temperatures from 70 °C to 500 °C. The temperature at which an amorphous zone fully recrystallises does not appear to be correlated with initial size. In addition, zones are occasionally observed to increase in size temporarily on some isochronal annealing steps. Furthermore, observations during a ramp anneal show that many zones recrystallise in a stepwise manner separated by periods of stability. These phenomenon are discussed in terms of the I-V pair.
Authors: D. Fink, Jiri Vacik, H.García Arellano, G.H. Muñoz, L. Alfonta, W.R. Fahrner, K. Hoppe, A. Kiv
Abstract: One of the strategies for enhancing the detection sensitivity of etched nuclear track-based biosensors uses the cladding of track walls with enzymes and the subsequent enrichment of charged enzymatic reaction products in the confined volume of the narrow tracks. For sensing two different bio-molecule types simultaneously, the tracks can be separated into two adjacent compartments by inserting a membrane in between them. The recipe for membrane formation is outlined. If the same enzyme is inserted into both compartments, the sensing accuracy can greatly be enhanced, as compared to etched tracks without membranes, due to a different underlying sensing mechanism. Such sensors act as frequency filters, which is useful for sensors operating in electrosmog-rich ambient.
Authors: Yuriy Perlovich, M. Grekhov, Margarita Isaenkova, Vladimir Fesenko, B. Kalin, V. Yakushin
Abstract: Irradiation of metal materials with low-energy ions is accompanied by the long-range effect, consisting in distinct texture and structure changes at the depth, exceeding, at least, by 104 times the thickness of the layer of ion retardation. In order to ascertain mechanisms of this effect, a layer-by-layer X-ray study was carried out as applied to ion-plasma treated cladding tubes of Zr- 1%Nb alloy for nuclear reactors. Impacts of pulse treatments with helium plasma by two different regimes and the ion energy of ~ 1 keV were compared. It was found, that only by minimal surface melting the ion-plasma treatment causes unpredictable bulk texture changes, consisting in arising of the axial texture component. The melted surface layer suppresses shock waves, associated with braking of ions and supposedly responsible for stimulation of dislocation processes at long distances from the surface.
Authors: Jesse Carter, En Gang Fu, S.M. McDeavitt, Xing Hang Zhang, Guo Qiang Xie, Lin Shao
Abstract: We have explored irradiation effects on metallic glasses by using 140 keV He ions. The mechanical properties of nanostructured metallic glass are studied by using microindentation. The study shows the feasibility of developing a high strength alloy by ion irradiation of metallic glasses.
Authors: Vito Raineri, Fabrizio Roccaforte, Sebania Libertino, Alfonso Ruggiero, V. Massimino, Lucia Calcagno
Abstract: The defects formation in ion-irradiated 4H-SiC was investigated and correlated with the electrical properties of Schottky diodes. The diodes were irradiated with 1 MeV Si+-ions, at fluences ranging between 1×109cm-2 and 1.8×1013cm-2. After irradiation, the current-voltage characteristics of the diodes showed an increase of the leakage current with increasing ion fluence. The reverse I-V characteristics of the irradiated diodes monitored as a function of the temperature showed an Arrhenius dependence of the leakage, with an activation energy of 0.64 eV. Deep level transient spectroscopy (DLTS) allowed to demonstrate that the Z1/Z2 center of 4H-SiC is the dominant defect in the increase of the leakage current in the irradiated material.
Authors: Feng Jiang Li, Jian Shuo Xing, Zi Qiang Zhao, Bing Chen Wei
Abstract: Metallic glasses (MGs) exhibit extremely high strength and superior resistance to corrosion. They are also supposed to be resistant against displacive irradiation due to their inherent disordered structure, and thereby are viewed as potential candidates for applications in irradiation environments. However, the structures and properties evolution of metallic glasses, especially bulk metallic glasses (BMGs), under irradiation has not been fully understood up to now. In this work, the structural stability and damage characteristics of a Zr-based BMG under helium ions irradiation environment were investigated. Meanwhile, the effect of structural relaxation and crystallization on the irradiation response of the BMG was also studied. Results show that the BMG reserves the amorphous structure within the studied range of fluence, and exhibits better irradiation resistance compared to that of the crystalline alloys. In our opinion, the initial free volume concentration affects the damage morphology of the BMG, while partial crystallization will lead to significantly embrittlement under irradiation.
Authors: Alfonso Ruggiero, M. Zimbone, Fabrizio Roccaforte, Sebania Libertino, Francesco La Via, Ricardo Reitano, Lucia Calcagno
Abstract: Deep-Level Transient Spectroscopy and room temperature photoluminescence were used to characterise a 6H-SiC epitaxial layer irradiated with 10 MeV C+ and to follow the defect annealing in the temperature range 300-1400 °C. The intensity of luminescence peak at 423 nm, related to band to band transitions, decreases after irradiation and it is slowly recovered after annealing in the temperature range 1000-1400 °C. The DLTS spectra of low temperature annealed samples show the presence of several overlapping traps, which anneal and evolve at high temperatures. After 1200 °C a main level at Ec-0.43 eV (E1/E2) is detected. The comparison between luminescence and DLTS results indicates that the defect associated with the E1/E2 level is mainly responsible for the luminescence quenching after irradiation.
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