Characterization of Collision Cascade Damage in Ca2La8(SiO4)6O2 by Hrtem

1994 ◽  
Vol 373 ◽  
Author(s):  
L.M. Wang ◽  
W.J. Webert
Keyword(s):  
Elevated Temperatures ◽  
Ion Beam ◽  
National Laboratory ◽  
Argonne National Laboratory ◽  
Sample Surface ◽  
Thermal Recovery ◽  
Collision Cascade ◽  
Cascade Damage

AbstractCa2La8(SiO4)6O2 thin crystals become amorphous under ion beam irradiation. The ion dose required for complete amorphization of the thin crystal (critical amorphization dose, Dc) increased with the increasing irradiation temperature and decreased with ion mass at elevated temperatures. Samples irradiated with 1-1.5 MeV Ar+, Kr+ and Xe+ ions to doses much lower than Dc, in the temperature range from 20 to 498 K were used for a detailed HRTEM investigation to study the amorphization process. The residual collision cascade damage after irradiation appeared as nanometer scale amorphous domains. The images of these domains are extremely sensitive to the sample thickness. Small domains of cascade size were found only at the very thin edge of the sample. In thicker regions, amorphous domains appear after higher doses as the result of cascade overlap in projection. At higher temperatures, the observed amorphous domains are smaller indicating thermal recovery at the amorphous/crystalline interface. The amorphous domains are also larger in size after irradiation with ions of higher mass at a fixed ion dose. These results are consistent with the Dc-temperature curves determined by in situ TEM with the HVEM-Tandem Facility at Argonne National Laboratory. The width of the amorphous rim along the edge of the specimen grew with increasing ion dose suggesting that amorphization also proceeds from the sample surface. Images of the collision cascade damage were compared to the cascade sizes calculated with the TRIM code. Some digitally acquired HRTEM images of the cascade damage were processed to reveal more detailed information.

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.

Amorphization Kinetics of Zr (Cr,Fe)2 Under Ion Irradiation

1992 ◽  
Vol 279 ◽  
Author(s):  
A. T. Motta ◽  
L. M. Howe ◽  
P. R. Okamoto
Keyword(s):  
Neutron Irradiation ◽  
Ion Irradiation ◽  
Ion Beam ◽  
National Laboratory ◽  
Argonne National Laboratory ◽  
Matrix Interface ◽  
Thin Foils ◽  
Intermetallic Precipitates ◽  
Kinetics Of

ABSTRACTThin foils of Zircaloy-4 were irradiated with 350 KeV 40Ar ions in the dual ion beam/HVEM facility at Argonne National Laboratory at 300 – 650 K. The irradiation-induced araorphization of the intermetallic precipitates Zr (Cr, Fe)2 and Zr2 (Ni, Fe) was studied in situ. For Zr (Cr,Fe)2 precipitates the dose-to-amorphization was found to increase exponentially with temperature, with a critical temperature of about 650 K. The amorphization morphology was shown to be homogeneous, with no preferential site for nucleation, in contrast to neutron-irradiation amorphization which started at the precipitate-matrix interface. For Zr2 (Ni,Fe) precipitates it was found that amorphization occurred at 550 K and 600 K, whereas in neutron irradiation no amorphization has been observed at those temperatures. The results are discussed in the context of the previous experimental results of neutron and electron irradiation and likely amorphization mechanisms are proposed.

The local structure of Ta(v) aqua ions in high temperature fluoride- and chloride-bearing solutions: Implications for Ta transport in granite-related postmagmatic fluids

2019 ◽  
Vol 57 (6) ◽  
pp. 843-851
Author(s):  
Alan J. Anderson ◽  
Robert A. Mayanovic ◽  
Thomas Lee
Keyword(s):  
High Temperature ◽  
Local Structure ◽  
Elevated Temperatures ◽  
National Laboratory ◽  
Argonne National Laboratory ◽  
Acidic Solutions ◽  
Diamond Anvil ◽  
X Ray Absorption ◽  
Photon Source

Abstract The local structure of Ta(V) in high-temperature fluoride- and chloride-bearing acidic solutions was investigated using in situ X-ray absorption spectroscopy (XAS). All XAS spectra were collected from two solutions, designated A and B, at beamline ID-20-C at the Advanced Photon Source, Argonne National Laboratory. Spectra were collected from solution A at 350 and 400 °C and from solution B at 25, 360, and 400 °C after the solutions were sealed in a hydrothermal diamond anvil cell. Solution A was prepared by dissolving Ta2O5 powder in 5% HF solution; solution B consisted of TaCl5 dissolved in 2% HF. The dominant tantalum species in solution A at elevated temperatures was TaF83–. In contrast, TaCl6–, which was the dominant complex in solution B at room temperature, disappeared as hydroxide complexes with an average ligand number between 5 and 7 became the dominant species at 350 and 400 °C. The XAS results confirm the previously recognized effect of fluoride activity on Ta speciation in hydrothermal fluids and suggest that both fluoride and hydroxide complexes play an important role in the transport of Ta in acidic fluoride-bearing solutions involved in the formation of mineralized mica-rich replacement units in granitic pegmatites.

Radiation-induced disordering and amorphization—An in situ HVEM study of uranium silicide with comparison to natural processes in zirconolite

1990 ◽  
Vol 48 (4) ◽  
pp. 534-535
Author(s):  
R. C. Birtcher ◽  
L. M. Wang ◽  
C. W. Allen ◽  
R. C. Ewing
Keyword(s):  
Electron Irradiation ◽  
Ion Irradiation ◽  
Ion Beam ◽  
National Laboratory ◽  
Argonne National Laboratory ◽  
Heavy Ion ◽  
High Energy ◽  
In Situ Tem ◽  
In Situ Experiments

We present here results of in situ TEM diffraction observations of the response of U3Si and U3Si2 when subjected to 1 MeV electron irradiation or to 1.5 MeV Kr ion irradiation, and observations of damage occuring in natural zirconolite. High energy electron irradiation or energetic heavy ion irradiation were performed in situ at the HVEM-Tandem User Facility at Argonne National Laboratory. In this Facility, a 2 MV Tandem ion accelerator and a 0.6 MV ion implanter have been interfaced to a 1.2 MeV AEI high voltage electron microscope. This allows a wide variety of in situ experiments to be performed with simultaneous ion irradiation and conventional transmission electron microscopy. During the electron irradiation, the electron beam was focused to a diameter of about 2 μ.m at the specimen thin area. The ion beam was approximately 2 mm in diameter and was uniform over the entire specimen. With the specimen mounted in a heating holder, the temperature increase indicated by the furnace thermocouple during the ion irradiation was typically 8 °K.

Ion-Beam Amortization of Ca2La2(SiO4)6O2 Single Crystals

1992 ◽  
Vol 279 ◽  
Author(s):  
William J. Weber ◽  
Lu-Min Wang
Keyword(s):  
Electron Microscopy ◽  
Single Crystals ◽  
Structural Changes ◽  
Ion Beam ◽  
National Laboratory ◽  
Argonne National Laboratory ◽  
Annealing Process ◽  
Recoil Energy ◽  
Transmission Electron

ABSTRACTSingle crystals of Ca2La8(SiO4)6O2 were irradiated with 1.5 MeV Xe+, 1.5 MeV Kr+, 1.0 MeV Ar+ and 0.8 MeV Ne+ ions to investigate the effects of recoil-energy spectrum, temperature, and crystallographic orientation on irradiation-induced amorphization. The irradiations were carried out using the HVEM-Tandem Facility at Argonne National Laboratory. The structural changes and the ion fluence for complete amorphization in the electron transparent thickness of the specimens were determined by in situ transmission electron microscopy. The displacement dose determined for complete amorphization was approximately 0.6 dpa for the Xe+, Kr+, and Ar+ ion irradiations but increased to 1.4 dpa for the Ne+ ion irradiations, which may reflect an effect of lower recoil energies. The ion fluence for complete amorphization increased exponentially with temperature over the range from 25 to 400°C. Amorphization was not observed at 500°C. The activation energy associated with this simultaneous annealing process was estimated to be 0.13 eV, and the critical amorphization temperature was estimated to be 438°C for the 1.5 MeV Kr+ irradiations.

Ion Beam Irradiation of Lanthanum Compounds in the Series La2O3-TiO2

2010 ◽  
Vol 1265 ◽  
Author(s):  
Karl Whittle ◽  
Mark Blackford ◽  
Robert Aughterson ◽  
Katherine L Smith ◽  
Gregory R Lumpkin ◽  
...  
Keyword(s):  
Ion Beam ◽  
National Laboratory ◽  
Argonne National Laboratory ◽  
Inverse Correlation ◽  
Critical Temperatures ◽  
Voltage Electron ◽  
Local Environments ◽  
Two Systems ◽  
User Facility

AbstractThin crystals of La2O3, La2/3TiO3, La2TiO5, and La2Ti2O7 have been irradiated in situ using 1 MeV Kr2+ ions in the Intermediate Voltage Electron Microscope-Tandem User Facility (IVEM-Tandem), at the Argonne National Laboratory (ANL). We observed that La2O3 remained crystalline to a fluence greater than 3.1 × 1016 ions cm-2 at a temperature of 50 K. The four binary oxide compounds in the two systems were observed through the crystalline-amorphous transition as a function of ion fluence and temperature. Results from the ion irradiations give critical temperatures for amorphisation (Tc) of 840 K for La2Ti2O7, 865 K for La2/3TiO3, and 1027 K for La2TiO5. The Tc values observed in this study, together with previous data for TiO2, are discussed with reference to the phase diagrams for La2O3-TiO2 systems and the different local environments within the crystal structures. Results suggest an observable inverse correlation between Tc and melting temperature (Tm) in the two systems.

Ion-Beam and Electron-Beam Induced Amorphization of Berlinite (AIPO4)

1994 ◽  
Vol 373 ◽  
Author(s):  
N. Bordes ◽  
R.C. Ewing
Keyword(s):  
Electron Microscopy ◽  
Electron Beam ◽  
Low Dose ◽  
Ion Beam ◽  
National Laboratory ◽  
Argonne National Laboratory ◽  
Crystalline Material ◽  
Small Areas ◽  
Transmission Electron

AbstractBerlinite (AIPO4) is isostructural with α-quartz. Like α-quartz, berlinite undergoes a pressure-induced amorphization at 15 ±3 GPa; however, upon release of the pressure, unlike α-quartz which remains amorphous, berlinite returns to the original crystalline structure of the single crystal. Berlinite was irradiated with 1.5 MeV Kr+ at temperatures ranging from 20 to 600K. The onset of amorphization was examined by monitoring the electron diffraction pattern by in situ transmission electron microscopy (TEM) at the HVEM-Tandem Facility at Argonne National Laboratory. The berlinite was easily amorphized at 20K at a relatively low dose of 4x1013 ions/cm2 or 0.05 dpa (displacements per atom). The critical amorphization dose increases with the sample temperature. These experiments also showed that the focused electron beam can locally amorphize the berlinite. After these irradiations, berlinite remained amorphous. At 500 °C, berlinite began to recrystallize: small areas of crystalline material appear in the aperiodic matrix. These results suggest that pressure-induced amorphization and ion-beam induced amorphization, in the case of berlinite, are different processes that result in two different aperiodic structural states.

Irradiation-induced grain growth in gold and copper: In situ HVEM studies at 75-300 K

1989 ◽  
Vol 47 ◽  
pp. 644-645
Author(s):  
Charles W. Allen
Keyword(s):  
Grain Growth ◽  
Ion Irradiation ◽  
Boundary Migration ◽  
Ion Beam ◽  
National Laboratory ◽  
Argonne National Laboratory ◽  
Average Grain Size ◽  
Growth Phenomenon ◽  
In Situ Experiments

When thin polycrystalline films of Au, Cu and various other materials are subjected to energetic ion irradiation, the average grain size increases even at cryogenic temperatures. As is the case with many ion beam processes, this phenomenon of ion irradiation induced grain growth exhibits only a very mild temperature dependence. This contribution 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 MV 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. A series of in situ ion and/or electron irradiation experiments is being performed at the HVEM-Tandem Facility at Argonne which have shown clearly for fine grained Au films that two mechanisms for growth are operative for the ion beam case: grain boundary migration as in normal thermal grain growth and grain coalescence which is similar in appearance to recrystallization by subgrain coalescence. Especially in the case of Au for which ion-induced growth is relatively rapid, such in situ experiments also demonstrate the importance of dislocation activity which is a consequence of the collision cascade damage associated with ion irradiation. Existing theories for irradiation-induced grain growth assume that growth occurs by boundary migration and that only point defects generated at grain boundaries are responsible for the growth phenomenon.

Ion-Beam-Driven Amortization of Ca2La8 (SiO4)6O2 Single Crystals

1993 ◽  
Vol 321 ◽  
Author(s):  
W. J. Weber ◽  
N. J. Hess ◽  
L. M. Wang
Keyword(s):  
Single Crystals ◽  
Structural Changes ◽  
Ion Beam ◽  
National Laboratory ◽  
Energy Levels ◽  
Argonne National Laboratory ◽  
Line Broadening ◽  
Spatially Resolved ◽  
Two Stages

ABSTRACTSingle crystals of Ca2La8(SiO4)6O2, with 1% Nd substituted for La, were irradiated with 0.8 MeV Ne+ and 1.5 MeV Kr+ ions over the temperature range from 15 K to 773 K. The irradiations were carried out using the HVEM-Tandem Facility at Argonne National Laboratory. The structural changes and the ion fluence for complete amorphization were determined by in situ transmission electron Microscopy. The ion fluence for complete amorphization increased with temperature in two stages associated with defect annealing processes. The critical temperature for amorphization increased from -360 K for 0.8 MeV Ne+ to -710 K for 1.5 MeV Kr+. During in situ annealing studies, irradiation-enhanced recrystallization was observed at 923 K. Spatially-resolved fluorescence spectra of the Nd ion excited with 488.0 nm laser excitation showed marked line-broadening toward the center of the amorphous regions. Initial Measurements indicate the subtle shifts of the 9I9/2 groundstate energy levels can be measured by pumping directly into the excited state 4F3/2 Manifold suggesting that the line broadening observed originates from a distribution of geometrically distorted Nd sites.

scholarly journals Strains in Thermally Growing Alumina Films Measured In-Situ Using Synchrotron X-Rays

2006 ◽  
Vol 522-523 ◽  
pp. 433-440 ◽  
Author(s):  
Peggy Y. Hou ◽  
A.P. Paulikas ◽  
B.W. Veal
Keyword(s):  
Elevated Temperatures ◽  
National Laboratory ◽  
Argonne National Laboratory ◽  
Phase Changes ◽  
X Rays ◽  
Growth Stresses ◽  
Alumina Films ◽  
Response To Stress ◽  
Diffraction Patterns

Strains in thermally grown oxides have been measured in-situ, as the oxides develop and evolve. Extensive data have been acquired from oxides grown in air at elevated temperatures on different model alloys that form Al2O3. Using synchrotron x-rays at the Advanced Photon Source (Beamline 12BM, Argonne National Laboratory), Debye-Scherrer diffraction patterns from the oxidizing specimen were recorded every 5 minutes during oxidation and subsequent cooling. The diffraction patterns were analyzed to determine strains in the oxides, as well as phase changes and the degree of texture. To study a specimen's response to stress perturbation, the oxidizing temperature was quickly cooled from 1100 to 950oC to impose a compressive thermal stress in the scale. This paper describes this new experimental approach and gives examples from oxidized β-NiAl, Fe-20Cr-10Al, Fe-28Al-5Cr and H2- annealed Fe-28Al-5Cr (all at. %) alloys to illustrate some current understanding of the development and relaxation of growth stresses in Al2O3.

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