Lead substitution in the bismuth superconductors (Bi,Pb)<inf>4</inf>Sr<inf>4</inf>Ca<inf>2</inf>Cu<inf>4</inf>O<inf>y</inf>and (Bi,Pb)<inf>4</inf>Sr<inf>3</inf>Ca<inf>3</inf>Cu<inf>4</inf>O<inf>y</inf>

Abstract

X-ray diffraction patterns and resistivity measurement of the Bi 4-x Pb x Sr 3 Ca 3 Cu 4 O y (x=0.7, 1.0, 1.1 and 1. 2) superconductors and the Bi 4-x Pb x Sr 4 Ca 2 Cu 4 O y (x=0.7, 0.9, 1.1 and 1.2) superconductors show that there are differences in the way the two superconductors respond to the Pb doping. The Pb doping is seen to promote the growth of the "2223" phase more in the "4334" systems than in the "4424" systems and to affect the zero-resistivity temperatures of the superconductors in different ways. © 1990.