Structural defects induced by heavy-ion irradiation in superconducting oxides

1993 ◽  
Vol 51 ◽  
pp. 1138-1139
Author(s):  
Yimei Zhu ◽  
H. Zhang ◽  
Z.X. Cai ◽  
R.C. Budhani ◽  
D.O. Welch ◽  
...  
Keyword(s):  
Heavy Ions ◽  
Defect Formation ◽  
Ion Irradiation ◽  
Ion Beam ◽  
Amorphous Region ◽  
Heavy Ion ◽  
Microscopy Study ◽  
Dynamical Theory ◽  
Structural Defects ◽  
Hole Density

We studied the the structure and properties of high Tc superconductors using heavy ions. While irradiation of YBa2Cu3O7-δ (hereafter denoted as 123) with 300 MeV Au+24 and 276 MeV Ag+21 ions produces columns of amorphous tracks along the ion trajectories, such defects are only created occasionally during irradiation with 236 MeV Cu+18, and are not induced with 182 MeV Si+13. A comprehensive electron microscopy study of defect formation in Bi2Sr2Ca2Cu3Ox, and in oxygen-reduced and ozone-treated 123, shows that the degree of radiation damage (the size and the shape of the defect) by the heavy ions depends on: (a) the rate at which ions lose their energy in the target; (b) crystallographic orientations with respect to the incident ion-beam (Fig.1); (c) thermal conductivity and chemical state (eg. oxygen concentration of 123) of the sample, and (d) the extent of pre-existing defects in the crystal. Calculation and simulation of the strain contrast surrounding the amorphous column using two-beam dynamical theory agree well with the observations and suggest that the reduced hole density observed in the crystal near the amorphous region is mainly due to lattice distortion.

scholarly journals Review of Swift Heavy Ion Irradiation Effects in CeO2

2021 ◽  
Vol 5 (2) ◽  
pp. 19
Author(s):  
William F. Cureton ◽  
Cameron L. Tracy ◽  
Maik Lang
Keyword(s):  
Heavy Ions ◽  
Defect Formation ◽  
Ion Irradiation ◽  
Ion Beam ◽  
Impurity Content ◽  
Heavy Ion ◽  
Atomic Scale ◽  
Experimental Conditions ◽  
Swift Heavy Ions ◽  
Wide Range

Cerium dioxide (CeO2) exhibits complex behavior when irradiated with swift heavy ions. Modifications to this material originate from the production of atomic-scale defects, which accumulate and induce changes to the microstructure, chemistry, and material properties. As such, characterizing its radiation response requires a wide range of complementary characterization techniques to elucidate the defect formation and stability over multiple length scales, such as X-ray and neutron scattering, optical spectroscopy, and electron microscopy. In this article, recent experimental efforts are reviewed in order to holistically assess the current understanding and knowledge gaps regarding the underlying physical mechanisms that dictate the response of CeO2 and related materials to irradiation with swift heavy ions. The recent application of novel experimental techniques has provided additional insight into the structural and chemical behavior of irradiation-induced defects, from the local, atomic-scale arrangement to the long-range structure. However, future work must carefully account for the influence of experimental conditions, with respect to both sample properties (e.g., grain size and impurity content) and ion-beam parameters (e.g., ion mass and energy), to facilitate a more direct comparison of experimental results.

Effect of Cascade Remnants on Freely Migrating Defects in Cu -1 % Au Alloys

1995 ◽  
Vol 396 ◽  
Author(s):  
A. Iwase ◽  
L. E. Rehn ◽  
P. M. Baldo ◽  
L. Funk
Keyword(s):  
Heavy Ions ◽  
Ion Irradiation ◽  
Ion Beam ◽  
Heavy Ion ◽  
The Other ◽  
Inert Gas ◽  
Heavy Ion Irradiation ◽  
Simultaneous Irradiation ◽  
Radiation Induced ◽  
Cu Ions

AbstractThe effects of cascade remnants on Freely Migrating Defects (FMD) were studied by measuring Radiation-Induced Segregation (RIS) in Cu-l%Au at 400°C during simultaneous irradiation with 1.5-MeV He and (400-800)-keV heavy ions (Ne, Ar or Cu). The large RIS observed during 1.5-MeV He-only irradiation was dramatically suppressed under simultaneous heavy ion irradiation. For Cu simultaneous irradiation, the suppression disappeared immediately after the Cu irradiation ceased, while for simultaneous inert gas (Ne or Ar) irradiation, the suppression persisted after the ion beam was turned off. These results demonstrate that the displacement cascades created by heavy ions introduce additional annihilation sites, which reduce the steady-state FMD concentrations. As the cascade remnants produced by Cu ions are thermally unstable at 400°C, the RIS suppression occurs only during simultaneous irradiation. On the other hand, the inert gas atoms which accumulate in the specimen apparently stabilize the cascade remnants, allowing the suppression to persist.

scholarly journals Nanoscale structural defects in oblique Ar+ sputtered Si(111) surfaces

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Divya Gupta ◽  
Mahak Chawla ◽  
Rahul Singhal ◽  
Sanjeev Aggarwal
Keyword(s):  
Oblique Incidence ◽  
Defect Formation ◽  
Ion Irradiation ◽  
Ion Beam ◽  
Structural Defects ◽  
High Dose ◽  
Extended Defect ◽  
Structured Surfaces ◽  
Self Assembled ◽  
Argon Ion

Abstract The present endeavor investigates the controlled surface modifications and evolution of self-assembled nano-dimensional defects on oblique Ar+ sputtered Si(111) surfaces which are important substrates for surface reconstruction. The defect formation started at off-normal incidences of 50° and then deflates into defined defect zones with decrease in oblique incidence, depending strongly on angle of ion incidence. Interestingly, it is observed that mean size & height decreases while average density of these defects increases with decreasing oblique incidence. Non-linear response of roughness of irradiated Si(111) with respect to oblique incidence is observed. Crystalline (c-Si) to amorphous (a-Si) phase transition under oblique argon ion irradiation has been revealed by Raman spectroscopy. Our analysis, thus, shows that high dose argon ion irradiation generates of self-assembled nano-scale defects and surface vacancies & their possible clustering into extended defect zones. Explicitly, ion beam-stimulated mass transport inside the amorphous layers governs the observed defect evolution. This investigation of crystalline (c-Si) coupled with amorphous (a-Si) phases of nano-structured surfaces provides insight into the potential applications in the nano-electronic and optoelectronic devices thus, initiating a new era for fabricating multitude of novel structures.

Electron and ion irradiation-induced dissolution of mechanical twins in the intermetalic U3Si: An in situ HVEM study

1989 ◽  
Vol 47 ◽  
pp. 652-653
Author(s):  
Charles W. Allen ◽  
Robert C. Birtcher
Keyword(s):  
Elevated Temperatures ◽  
Ion Irradiation ◽  
Ion Beam ◽  
National Laboratory ◽  
Argonne National Laboratory ◽  
Heavy Ion ◽  
High Energy ◽  
Mechanical Twinning ◽  
In Situ Experiments

The uranium silicides, including U3Si, are under study as candidate low enrichment nuclear fuels. Ion beam simulations of the in-reactor behavior of such materials are performed because a similar damage structure can be produced in hours by energetic heavy ions which requires years in actual reactor tests. This contribution treats one aspect of the microstructural behavior of U3Si under high energy electron irradiation and low dose energetic heavy ion irradiation and is based on in situ experiments, performed at the HVEM-Tandem User Facility at Argonne National Laboratory. This Facility interfaces a 2 MV Tandem ion accelerator and a 0.6 MV ion implanter to a 1.2 MeV AEI high voltage electron microscope, which allows a wide variety of in situ ion beam experiments to be performed with simultaneous irradiation and electron microscopy or diffraction.At elevated temperatures, U3Si exhibits the ordered AuCu3 structure. On cooling below 1058 K, the intermetallic transforms, evidently martensitically, to a body-centered tetragonal structure (alternatively, the structure may be described as face-centered tetragonal, which would be fcc except for a 1 pet tetragonal distortion). Mechanical twinning accompanies the transformation; however, diferences between electron diffraction patterns from twinned and non-twinned martensite plates could not be distinguished.

scholarly journals Comparison of short-range order in irradiated dysprosium titanates

2021 ◽  
Vol 5 (1) ◽  
Author(s):  
Roman Sherrod ◽  
Eric C. O’Quinn ◽  
Igor M. Gussev ◽  
Cale Overstreet ◽  
Joerg Neuefeind ◽  
...  
Keyword(s):  
Long Range ◽  
Short Range ◽  
Structural Model ◽  
Ion Irradiation ◽  
Function Analysis ◽  
Ion Beam ◽  
Structural Response ◽  
Heavy Ion ◽  
Range Order ◽  
Radiation Resistant

AbstractThe structural response of Dy2TiO5 oxide under swift heavy ion irradiation (2.2 GeV Au ions) was studied over a range of structural length scales utilizing neutron total scattering experiments. Refinement of diffraction data confirms that the long-range orthorhombic structure is susceptible to ion beam-induced amorphization with limited crystalline fraction remaining after irradiation to 8 × 1012 ions/cm2. In contrast, the local atomic arrangement, examined through pair distribution function analysis, shows only subtle changes after irradiation and is still described best by the original orthorhombic structural model. A comparison to Dy2Ti2O7 pyrochlore oxide under the same irradiation conditions reveals a different behavior: while the dysprosium titanate pyrochlore is more radiation resistant over the long-range with smaller degree of amorphization as compared to Dy2TiO5, the former involves more local atomic rearrangements, best described by a pyrochlore-to-weberite-type transformation. These results highlight the importance of short-range and medium-range order analysis for a comprehensive description of radiation behavior.

Ion beam-mixing effects in nearly lattice-matched AlInN/GaN heterostructures by swift heavy ion irradiation

2012 ◽  
Vol 167 (7) ◽  
pp. 506-511 ◽  
Author(s):  
G. Devaraju ◽  
S. V.S. Nageswara Rao ◽  
N. Srinivasa Rao ◽  
V. Saikiran ◽  
T. K. Chan ◽  
...  
Keyword(s):  
Ion Irradiation ◽  
Ion Beam ◽  
Heavy Ion ◽  
Ion Beam Mixing ◽  
Swift Heavy Ion Irradiation ◽  
Heavy Ion Irradiation ◽  
Mixing Effects ◽  
Swift Heavy Ion ◽  
Lattice Matched

The Complementary Nature of Electron Microscopy and ION Channeling for the Assessment of Radiation Damage Evolution in Ceramics

1998 ◽  
Vol 4 (S2) ◽  
pp. 558-559
Author(s):  
K. E. Sickafus
Keyword(s):  
Damage Evolution ◽  
Ion Irradiation ◽  
Ion Beam ◽  
Quantitative Measure ◽  
Heavy Ion ◽  
Damage Parameter ◽  
Irradiation Damage ◽  
Damage Level ◽  
Ion Channeling ◽  
Typical Experiment

In ion irradiation damage studies on ceramics, damage evolution is often assessed using Rutherford backscattering spectroscopy and ion channeling (RBS/C) techniques. In a typical experiment, a single crystal ceramic sample is irradiated with heavy ions and then the crystal is exposed to He ions along a low-index crystallographic orientation. Simultaneously, the backscattered He ion yield is measured as a function of ion energy loss. For He ions scattered from the heavy ion irradiated volume, the He ion yield increases in proportion to the heavy ion dose. The RBS/C yield rises because the He ion beam is dechanneled by, for instance, interstitial point defects and clusters and their associated strain fields. A quantitative measure of dechanneling is denoted by χmin, defined as the ratio of the He ion yield along a low-index crystal orientation, to the yield obtained in a random (non-channeling) orientation. The damage parameter xmin varies from 0 to 1, where 1 represents the maximum damage level that can be measured by RBS/C.

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