Crystallization process in Pb-free or Pb-doped Bi2−xPbxSr2Ca2Cu3O10−y glass system

Broadening of the resistive transition in polycrystalline Bi/Pb-2223

“…The double logarithmic plot of the total dissipation P against the magnetic field B (figure 2) shows that P varies proportionally to B 0.69 . This exponent is very close to a value of 2 3 , as proposed by Tinkham [21]. The viscosity coefficient η of the vortex system reflecting the magnitude of intervortex interactions in a vortex liquid state was calculated and plotted in figure 3.…”

“…However, pinning centres can be secondary phases. Therefore some optimization must be found and that is why so many synthesis routes have been attempted [1][2][3][4][5][6][7][8][9][10][11][12][13][14], including rare earth substitution for grain alignment in a magnetic field. Let us recall that the role of Pb is still disputed.…”

A new model for the formation of high-T c phase in superconductive (Bi, Pb)2Sr2Ca2Cu3O x glass-ceramics

“…It has been clarified that the 2212 phase forms at around 780C in samples prepared by a melting method and that a liquid phase, formed at around 760 C, enormously enhances the growth of the 2212 phase by easing oxidation of Cu + into Cu 2+ and by easing diffusion of Ca 2+ and Cu 2 + entities toward the 2212 phase [11]. As is well known, the substitution of Pb for Bi is essential for the formation of the high-To phase, but the role of Pb remains unclear.…”

“…The difficulty in preparing the high-T~ phase revealed that an understanding of the formation of high-T~ phase is prerequisite for the fabrication of superconductors containing pure high-To phase with high quality. The formation mechanism of the high-To phase was extensively discussed by many authors [6][7][8][9][10][11]. Even 0957 4522 ~; 1996 Chapman & Hall though different approaches were made so far, many points concerning the formation mechanism of the high-To phase are still obscure.…”