DEFORMATION INDUCED DEFECTS IN REBA2CU3O7-DELTA

In this paper, we report the microstructural characterization of bulk rare-earth (Re = Nd or Y) Re123 ceramic superconductors subjected to different levels of stress at various confining pressures, strain rates, and temperatures. This includes several classes of samples: (i) deformed under constant stress, (ii) deformed at a constant strain rate of 10-4s-1, (iii) hand-ground in a mortar and pestle, and (iv) shock-compacted at 167 kbar. Deformation conditions for these samples spanned a wide range of processing conditions: 10-7 to 10-5s-1 in strain rate, temperatures of 25°C to 1020°C, and pressures from 1 atm to 167 kbar. Dislocations were always observed to lie on the (001) planes having Burgers vectors of 〈100〉 and possibly 〈110〉. Small amounts of strain can be accommodated by deformation twinning on the {110} planes. High temperature anneal of the Y123 results in the formation of extrinsic stacking faults with R = 1 6[031], with an intercalation of an extra CuO layer offsetting the Ba atoms by half a unit cell in the b-axis direction. These stacking faults are not observed in the Nd123. Further work is in progress to better understand the interactions of the line and planner defects on the superconducting properties of these materials. © 1990.