Structure of Water and Electron Beam Damaged High Temperature Superconductors

1987 ◽  
Vol 99 ◽  
Author(s):  
J. P. Zhang ◽  
D. J. Li ◽  
L. D. Marks
Keyword(s):  
Electron Beam ◽  
High Temperature ◽  
Water Vapour ◽  
Amorphous Phase ◽  
Barium Carbonate ◽  
Ion Beam ◽  
High Temperature Superconductors ◽  
Barium Oxide ◽  
Oxide Surface ◽  
Preferential Formation

ABSTRACTHigh Resolution electron microscope observations of the effect of water vapour and the electron beam on high temperature superconductors indicate that the effects are very similar. Water vapour leads to the decomposition into a barium compound which in the microscope is barium oxide (presumably barium carbonate in air) which takes the form of whiskers on the surface and the green and brown phases. The electron beam first produces a true surface amorphous phase which on prelonged irradiation develops a barium oxide surface coating. Different from the results of ion beam damage, we have not seen any evidence for preferential formation of the amorphous phase at grain boundaries. These results indicate that as the oxygen content of the material is reduced, the barium cations become more mobile and can therefore diffuse out to the surface.

Crystallization of nano-size thallous oxide during ion irradiation of Tl-Ba-Ca-Cu-O high-temperature superconductors

1995 ◽  
Vol 53 ◽  
pp. 214-215
Author(s):  
P. P. Newcomer ◽  
L. M. Wang ◽  
M. L. Miller ◽  
R. C. Ewing
Keyword(s):  
High Temperature ◽  
Ion Irradiation ◽  
Ion Beam ◽  
High Temperature Superconductors ◽  
National Laboratory ◽  
Argonne National Laboratory ◽  
Planetary Science ◽  
University Of New Mexico ◽  
The University ◽  
Nano Size

The Tl-Ba-Ca-Cu-O class of type-II high temperature superconductors (HTS) have Tc's as high as 125K. Although they have good critical current values, when a field is applied the weak pinning and consequent flow of magnetic vortices are a major impediment to the usefulness of these materials. Ion irradiation has been shown to enhance the pinning. High quality single crystals, as determined with x-ray precession and HRTEM, with sharp HTS Meissner signals, were irradiated with 1.5 MeV Kr+ and Xe+ ions using the HVEM-Tandem facility at Argonne National Laboratory. Ion beam microstructural modification was studied in-situ using electron diffraction and after irradiation using HRTEM and nano-beam EDS on Tl-1212 and Tl-2212 (numbers designate the stoichiometry Tl-Ba- Ca-Cu-O) single-crystal HTS. After irradiation, microstructure was studied using the JEOL 2010 in the Earth and Planetary Science Department at the University of New Mexico in order to characterize the resulting irradiation-induced nano-size precipitates.

Ion-beam direct-structuring of high-temperature superconductors

2006 ◽  
Vol 83 (4-9) ◽  
pp. 1495-1498 ◽  
Author(s):  
W. Lang ◽  
M. Dineva ◽  
M. Marksteiner ◽  
T. Enzenhofer ◽  
K. Siraj ◽  
...  
Keyword(s):  
High Temperature ◽  
Ion Beam ◽  
High Temperature Superconductors

Ion Beam Modification of TI-Ba-Ca-Cu-O Type High Temperature Superconductors During Irradiation

1994 ◽  
Vol 373 ◽  
Author(s):  
P.P. Newcomer ◽  
L. M. Wang ◽  
B. Morosin
Keyword(s):  
High Temperature ◽  
Ion Irradiation ◽  
Ion Beam ◽  
High Temperature Superconductors ◽  
Ion Beam Modification ◽  
Moiré Fringes ◽  
High Resolution Tem ◽  
20 Nm ◽  
Induced Crystallization

AbstractMicrostructural modification of high temperature superconductor (HTS) single-crystal plates of T1-1212 and T1-2212 (numbers designate the Tl/Ba/Ca/Cu cation ratio) was studied during 1.5 MeV Kr+ and Xe+ ion irradiation with in-situ electron diffraction and after ion irradiation with high resolution TEM (HRTEM). Similar in-situ temperature dependence effects are seen for both phases. During irradiations from 22K to 673K, an amorphous halo develops after very low ion dose or fluence (l.7X1012 ions/cm2). During irradiation at 100K and 300K, complete amorphization is obtained, while at 22K and ≥533K, the halo fades slightly and a polycrystalline ring pattern develops, indicating ion irradiation induced crystallization occurred. After a low ion dose (8.5XlO12ions/cm2) at 100K and 300K, HRTEM reveals amorphous regions 5 -20 nm in size which are not columnar and do not all penetrate the entire sample thickness. At 22K and ≥533K, Moire fringes and misoriented crystallites of cascade size are observed. The 4 - 6nm crystallites are thallium-rich.

A Study of Zircaloy-2 Corrosion in High Temperature Water Using Ion Beam Methods

CORROSION ◽  
1981 ◽  
Vol 37 (10) ◽  
pp. 575-585 ◽  
Author(s):  
I. S. Woolsey ◽  
J. R. Morris
Keyword(s):  
High Temperature ◽  
Ion Beam ◽  
Short Circuit ◽  
Oxide Surface ◽  
Aqueous Corrosion ◽  
Protective Oxide ◽  
Transport Behavior ◽  
High Temperature Water ◽  
Diffusion Paths ◽  
Temperature Water

Abstract Corrosion experiments have been carried out on Zircaloy-2 specimens in water at 355 C to study the transport of oxygen and hydrogen (as deuterium) in growing corrosion films. The transport behavior was studied by using O18 and deuterium labelled water, and analyzing the corrosion films for these isotopes by the use of ion beam induced nuclear reactions. Analysis for O18 was performed by means of the O18 (p,α)N15 reaction, using incident 850 and 950 keV protons. The analyses for deuterium were made using the D(He3,d)p reaction employing incident 850 and 1300 keV He3 ions, and detecting the scattered α-particles. The composition of the corrosion films was also examined in 2.9 MeV and 3.9 MeV α-particle backscattering experiments. From these studies, it was concluded that the corrosion of Zircaloy-2 in high temperature water occurs predominantly by oxygen diffusion through the corrosion film via grain boundary or similar short circuit diffusion paths, to form fresh oxide at the oxide metal interface. The diffusivity of oxygen through the pre-breakaway films decreased with time as a result of a decrease in the available easy diffusion paths as the oxide aged. This was interpreted as the primary cause of the subparabolic kinetics normally observed prior to the rate transition during high temperature aqueous corrosion of Zircaloy-2. There was also evidence that increasing grain size deeper within thick pre-breakaway films contributes to the decrease in oxygen diffusivity. The oxygen transport behavior in post-breakaway corrosion films indicates that the rate transition results from the generation of new diffusion pathways in previously protective oxide. Unexpectedly high concentrations of deuterium were observed in the corrosion films. These were about 4.5% atomic at the oxide surface, falling to 1 % atomic at depths between 1 and 1.5 μm. The deuterium was also found to be highly mobile within the oxide, much more so than oxygen.

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