Growth mechanism of high Tc phase in leaded BiSrCaCuO system

Application of elevated magnetic fields during growth of BiSrCaCuO superconducting whiskers and studies of growth defects for better understanding of the growth mechanism

“…For the BiSrCaCuO un-doped ceramic, 'nucleation and growth' type mechanisms or mechanisms involving a liquid phase are described in the Ref. [45][46][47][48][49][50][51][52][53][54], but several other growth models, such as intercalation, exchange, pipediffusion, one-dimensional diffusion along the caxis, epitaxial growth starting from a primary phase [45][46][47][48][55][56][57][58][59][60][61][62][63][64] were also introduced. Generally, these models are considered to belong to the so-called 'solid-state' growth models, although a clear separation between them or between them and 'nucleation and growth' models is difficult and many articles reported simultaneous occurrence of several mechanisms.…”

Fabrication and Characterization of High- TcSuperconducting Continuous-Tube-Forming/Filling Bi(Pb)-2223/Ag Composites and Coils

“…Various authors have reported that the reaction corresponding to the DTA peak 344 just before melting occurs seems to be a necessary condition for growth of the 2223 phase (22)(23)(24). The region containing a liquidphase is often referredto as the region of partial melting, which can cover a temperature range of up to -30°C, beginning at the onset of melting temperature, as reported by Yamada et al …”

“…(25). The favorable sintering temperature (T) for 2223 phase formation for precursor powders has also been shown to be bounded between the endothermic partial melting peak (T pm ) and the maximum peak at which melting occurs (T m ) , obtainable from DTA curves (22,24,26). Figures 7 and 8 show respectively the DTA curves obtained for the five different precursor powders and two composites of Bi(Pb)-2223.…”

Influence of Pb doping on properties of BSCCO superconductor

“…Superconducting phase will be formed by precipitation from melting phase. It has been also shown that Pb substitution is responsible for significant reduction of intergrowth defects near grain boundaries [12,13]. Considering that when Pb substitutes Bi in the 2212 phase there is a change in the temperature onset To and in Tco, while in the 2223 phase there are no significant variations in To and in Tco between doped and undoped situation, it seems that Pb acts substitutionally in one of the uncontrolled present phase, because of the dependence of Tco on the Pb stoichiometry.…”