scholarly journals Radiation Induced Amorphization in YBa2 Cu3O7 and GdBa2 Cu3O7 Superconductors

1988 ◽  
Vol 128 ◽  
Author(s):  
Don M. Parkin ◽  
Michael Nastasii
Keyword(s):  
Rare Earth ◽  
High Temperature ◽  
Amorphous Phase ◽  
Metal Atom ◽  
High Temperature Superconductors ◽  
Low Doses ◽  
Rare Earth Atom ◽  
Particle Irradiation ◽  
Radiation Induced

ABSTRACTThe response of YBa2Cu3O7 and GdBa2Gu3O7 high temperature superconductors to particle irradiation is examined. Both ion and electron irradiations have been shown to first produce an orthorhombic-to-tetragonal transformation at relatively low doses followed by a tetragonal-to-amorphous transformation at doses roughly a factor of 10 higher. Analysis of the displacement stoichiometry that results from 120, 300, and 1000 keV electron irradiations, 400, and 500 keV O irradiations, and 300 keV helium irradiations indicate that the orthorhombic-to-tetragonal transformation is driven by O atom displacements either alone or in the presence of metal atom displacements and that the transformation to the amorphous phase is driven by displacements on the Y, Gd or other rare earth atom site.

Ternary Rare Earth Transition Metal Zinc Compounds RT2Zn20 with T = Fe, Ru, Co, Rh, and Ni

1997 ◽  
Vol 52 (9) ◽  
pp. 1023-1030 ◽  
Author(s):  
Tono Nasch ◽  
Wolfgang Jeitschko ◽  
Ute Ch. Rodewald
Keyword(s):  
Rare Earth ◽  
Transition Metal ◽  
Metal Atom ◽  
Transition Metal Atom ◽  
Hexagonal Prism ◽  
Rare Earth Atom ◽  
Zinc Compounds ◽  
A Site ◽  
Cold Pressed ◽  
Zinc Site

Forty eight new compounds RT2Zn20 were prepared by annealing cold-pressed pellets of the elemental components in an argon atmosphere. They crystallize with the cubic CeCr2Al20 type structure (Fd3̅̅m , Z = 8), which was refined from single-crystal diffractometer data of TbFeiZn20 (a = 1411.1(1) pm ), YRu2Zn20 (a = 1422.6(1) pm ), DyRu2Zn20 (a = 1422.1(1) pm), GdCo2Zn20 (a = 1406.0(1) pm ), DyRh2Zn20 (a = 1418.2(1) pm ), and TmNi2Zn20 (a= 1401.6(1) pm) to conventional residuals varying betw een R = 0.011 and R - 0.024. The com pounds have a tendency for tw inning, thus m im icking hexagonal sym metry, with the cubic [111] axis as the axis w ith the pseudohexagonal symmetry. M inor inconsistencies in the cell volum es of these com pounds indicate slight deviations from the ideal com position. N evertheless, the five atom ic sites of this structure w ere found to be fully occupied w ithin the error lim its w ith the exception of one zinc site of TmNi2Zn20. The coordination for the site of the rare earth atom s is a Frank-K asper polyhedron with coordination num ber (CN) 16. The transition metal atom s occupy a site w ith icosahedral zinc coordination (CN 12). Two of the three zinc sites are in pentagonal prism atic coordination of zinc atom s, capped by rare earth and/or transition metal atom s (CN 12), w hile the third zinc site has 12 zinc neighbors form ing a hexagonal prism , w hich is capped by tw o rare earth atom s (CN 14).

Rare-earth-Cu interaction in high-temperature superconductors

1997 ◽  
Vol 230-232 ◽  
pp. 853-855
Author(s):  
C. Quitmann ◽  
B. Beschoten ◽  
G. Güntherodt ◽  
M. Onellion
Keyword(s):  
Rare Earth ◽  
High Temperature ◽  
High Temperature Superconductors

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.

MAGNETIC PROPERTIES OF SUPERCONDUCTING nMBa2Cu3Ox:Ag (M = Y, Gd, and Eu) COMPOSITES

1989 ◽  
Vol 03 (16) ◽  
pp. 1251-1265
Author(s):  
C. Y. HUANG ◽  
T. J. LI ◽  
Y. D. YAO ◽  
L. GAO ◽  
Z. J. HUANG ◽  
...  
Keyword(s):  
Magnetic Properties ◽  
Rare Earth ◽  
High Temperature ◽  
High Temperature Superconductors ◽  
Hysteresis Loops ◽  
Residual Magnetization ◽  
Rare Earth Ions ◽  
Pinning Force ◽  
Processing Conditions ◽  
The Rare Earth

We measured the M-H hysteresis loops of n YBa 2 Cu 3 O x: Ag (n = 3, 5, and 7) and 3RBa 2 Cu 3 O x: Ag (R = Gd and Eu) as a function of temperature, and found that the residual magnetization and, hence, pinning is independent of n and the rare-earth ions (R and Y), but depends greatly on the processing conditions. These samples exhibit the strongest pinning force for high-temperature superconductors developed to date.

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