Structural modulation and superconducting properties in Bi2-xPbxSr2CaCu2O8+d and Bi2-yPbySr2YCu2O8+d

Two-Phase Microstructures Generating Efficient Pinning Centers in the Heavily Pb-Substituted Bi2Sr2CaCu2O8+Single Crystals

“…The ¹ onset varied slightly with Pb content as 87, 85, 83, and 85 K for x"0, 0.4, 0.6, and 0.7, respectively. It was reported in a previous study on polycrystalline samples annealed at 750°C in nitrogen flow that ¹ was raised above 90 K by the Pb substitution (10). The observed decrease in ¹ for the present crystals prepared in air must be due to the overdoping effect resulting from higher oxygen content.…”

“…The wavelength along the b axis is 4.8b (b&0.54 nm), but increases monotonically with Pb substitution; wavelengths of 6.0b to 7.3b were reported for y"0. 10,[27][28][29] and also of 8.2b to 9.2b for y&0.4 (30). Even the disappearance of the modulation was reported for y50.6 (10, 13) or for y50.48 (30) in polycrystalline samples.…”

“…However, the improvement in J should be more significant in Bi-2212 because of its inherent strong anisotropy. Another point important to note is that ¹ depends upon Pb content; ¹ , when optimized, first increases, reaches a maximum of 93 K at y"0.2 or 95 K at y"0.4, and then decreases down to 90 K at y"0.6 (10). Then, the present two phases with different Pb contents could have slightly different ¹ 's.…”

“…Pb substitution of about 0.3 per formula unit is essential to the formation itself of Bi Sr Ca Cu O >B (Bi-2223) (9), while a range of solid solutions exist for Bi-2212 and Bi Sr CuO >B (Bi-2201) (10)(11)(12). In the case of Bi-2212, a series of single-phase polycrystalline materials were obtained for 04y40.8 in a formula Bi \W Pb W Sr CaCu O >B (10,13,14).…”

Pb0.4Bi1.6Ma1, Alméras2, Kelley3 et al. 1995Phys. Rev. B

“…It was then found that the lead substitution has a strong influence on the incommensurate modulation that exists in the b−axis. [24][25][26][27][28][29] in both Bi−2212 and Bi−2223.…”