Probing (Bi0.92Pb0.17)(2)Sr1.91Ca2.03Cu3.06O10+delta superconductors from 30 to 300 K by positron-lifetime measurements

The present measurement of positron annihilation lifetimes for the high-T-c superconductor (Bi0.92Pb0.17)(2)Sr1.91Ca2.03Cu3.06O10+delta or (Bi,Pb)-222 3, as a function of temperature, has been inspired by our recent DBPARL (Do ppler-broadened positron annihilation radiation line shape) finding of a st ep and minima in the region around T-c(R = 0) = 104 K, in the variation wit h temperature, of the fraction of low momentum electrons at the annihilatio n sites. The positron annihilation lifetime in the superconductor probes th e number density of electrons at the annihilation sites. The present work o bserves a reduction of lifetime components in the T-c region. Significant c hanges in the lifetime components in other temperature regions have also be en observed and discussed. [S0163-1829(98)05745-2].