Non-in situ pressure effects on the superconducting characteristics and microstructure in Bi-Ca-Sr-Cu-O systems

Abstract

Results on the pressure dependence of the transition temperatureT _c and the resistancetemperature behaviour of Bi₂Ca₁ Sr₂Cu₂O_x compound are presented. Both the onsetT _c and theT _c (R = O) are found to decrease with increasing pressure in the 0 to 50 kbar (1 bar = 10⁵Pa) range. Up to 20 k bar, the normal state resistivity is seen to be metallic beyond which it becomes semiconducting. The pressure is found to reduce theT _c at a rate of 0.2 K kbar⁻¹. The scanning electron micrographs of the starting bismuth cuprates showed characteristic needle-like structure, whereas the pressurized samples were found to be particularly different, consisting of small grains.