SUPERCONDUCTIVITY AND MICROSTRUCTURE OF INFINITE-LAYERED (SRND)CUO2 PREPARED UNDER HIGH-PRESSURE

Superconductors of the (SrNd) CuO2 family with infinite CuO2 layers ha ve been prepared by treatment at about 1 000-degrees-C and high pressu res of 3.0 GPa and 3.5 GPa. The superconductivity and microstructure o f (SrNd)CuO2 have been investigated by resistance and AC susceptibilit y measurements, and transmission electron and scanning electron micros copes. The results show a superconducting transition at 34 K and a met al-like behavior of the normal state resistance. A transition of struc ture modulation appeared at a temperature near 600 K when the sample w as heated in the electron microscope chamber under a vacuum of 10(-6) Torr. A small drop at about 60 K in the resistance curve seems to come from a phase transition.