The effects of 3.5-GeV Xe ion irradiation on the superconducting ($T_c$, $J_c$) and normal (R) properties of the high-$T_c$ superconductors ${\mathrm{YBa}}_{2\mathrm{Z}}$${\mathrm{Cu}}_3$${\mathrm{O}}_{7\mathrm{-}\mathrm{\delta }}$ with 0.1≤δ<0.7 have been investigated by means of n situ resistance measurements between 4.2 and 105 K. It is shown that the decrease of the $T_c$ offset and the concomitant increase of the resistance in the normal state are strongly enhanced by inelastic collisions which lead to the production of discontinuous tracks of extended defects visualized by high-resolution electron microscopy. These defects act as pinning centers for the flux lines and result in the improvement of the critical density $J_c$ by a factor of 3.5 (H=0, T=5 K) for a Xe fluence of 2.5×${10}^{11}$ ${\mathrm{cm}}^{\mathrm{-}2}$. The greater sensitivity to irradiation damage of the phases corresponding to low oxygen contents (δ=0.46 and 0.62) has been attributed to the particular structure of these compounds which exhibit, as has been previously reported, intergrowths of insulating ${\mathrm{YBa}}_2$${\mathrm{Cu}}_3$${\mathrm{O}}_6$ regions or chains with superconducting ${\mathrm{YBa}}_2$${\mathrm{C}}_3$${\mathrm{O}}_7$ regions or chains.

• Received 19 December 1988

DOI:https://doi.org/10.1103/PhysRevB.39.6549