Samples of high-temperature superconductors of Tl-1212 or Tl-2212 form were subjected to 1.5MeV Kr+ or Xe+ ion bombardment at temperatures of 20 to 650K. During bombardment of the single crystals, microstructural modification was observed  in situ  by means of electron diffraction and was found to exhibit a marked temperature dependence. At certain temperatures, bombardment was continued up to the critical fluence at which the original structure disappeared. The temperature dependence of this critical fluence went through a minimum near to the superconducting transition temperature, and was related to the temperature dependence of the thermal conductivity; which had its maximum value near to this temperature. At irradiation temperatures which were near to this maximum in thermal conductivity, a minimum amount of damage recovery occurred because heat dissipated away from the displacement cascades. On the other hand, ion bombardment depressed the critical temperature. The rate of decrease in this temperature as a function of damage (measured in dpa) was found to be the same for ions of He+, O2+ and Au5+; thus showing that damage accumulation was a result of atomic collisions. The rate of decrease in the transition temperature was also found to be the same for both transport and magnetization data; thus indicating that the displacements affected the bulk of the samples via point defect creation. An activation energy of 0.4eV was found for bombardment damage recovery at temperatures ranging from 100 to 650K.

P.P.Newcomer, J.C.Barbour, L.M.Wang, E.L.Venturini, J.F.Kwak, R.C.Ewing, M.L.Miller, B.Morosin: Physica C, 1996, 267[3-4], 243-53