The effect of manganese on phase formation and properties of Bi2212 ceramics

In this work we present a systematic study of the Mn influence superconducting properties. Attempts have been made to identify the optimum inclusion of MnO₂ in Bi₂Sr₂Ca₁Cu₂O_8+δ superconductors. The phase formation, texture and grain alignments were analysed by X-ray diffraction, scanning electron microscopy, energy dispersive spectrometry (SEM, EDS) and electrical resistivity. It was found that Mn addition has affected the formation of the desired Bi-2212 phase and the microstructure of these samples thereby influencing on the resistivity. The resistivity of all the Bi₂Sr₂Mn _x Ca₁Cu₂O_8+δ samples shows metallic behaviour. It reveals that, 4 wt% composite exhibits a better superconducting property in comparison with pure BSCCO. It has been observed that Mn residing at the grain boundary of BSCCO matrix influences the tailing region with having significant change in the critical temperature. The microstructures observed by SEM indicate segregation of an additional phase. The EDS revealed that this phase is stoichiometric. The results show that the doping leads to a reduction of cell volume as well as the c axis.