Growth, microstructures, and superconductivity of Bi2–xPbxSr2Ca1–yGdyCu2O8 + z single crystals

X. L. Wang, University of Wollongong
E. Takayama-Muromachi, National Institute for Materials Science, Japan
A. H. Li, University of Wollongong
Z. Cheng, University of Wollongong
S. Keshavarzi, University of Wollongong
M. J. Qin, University of Wollongong
S. X. Dou, University of Wollongong

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This article was originally published as: Wang, XL, Takayama-Muromachi, E, Li, AH, Cheng, ZX, Keshavarzi, S, Qin, MJ & Dou, SX, Growth, microstructures, and superconductivity of Bi2–xPbxSr2Ca1–yGdyCu2O8 + z single crystals, Journal of Applied Physics, June 2004, 95(11), 6699–6701. Copyright American Institute of Physics. Original journal available here.

Abstract

Bi2–xPbxSr2Ca1–yGdyCu2O8 + delta (x = 0.34 and y = 0.18, 0.34) crystals were grown by the self-flux method. The crystals have a cleavage thickness of only half unit cell up to two unit cells with Tc only dropping 20 K as y is increased from 0.18 to 0.34 for as-grown crystals. However, Tc increased to almost the same value of about 80 K after annealing in air regardless of the Gd doping levels. The co-doping produced enhanced flux pinning compared to the sole Gd doping. A secondary peak effect presented in crystals with x = 0.34 and y = 0.34 was explained by phase segregations containing Gd-rich clusters.