Formation of the 110-K superconducting phase via the amorphous state in the Bi-Sr-Ca-Cu-O system

Donglu Shi; Ming Tang; K. Vandervoort; H. Claus

doi:10.1103/PhysRevB.39.9091

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Formation of the 110-K superconducting phase via the amorphous state in the Bi-Sr-Ca-Cu-O system

Donglu Shi, Ming Tang, K. Vandervoort, H. Claus

DOI 10.1103/PhysRevB.39.9091 · Physical Review B

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Abstract

The thermodynamic and kinetic behavior of both the 85 and 110-K superconducting phases during the crystallization annealing process have been observed and analyzed using x-ray diffraction, magnetic shielding, and resistivity measurements in crystallized Bi-Sr-Ca-Cu-O glasses with nominal compositions Bi2Sr2Ca2Cu3Ox (2:2:2:3), Bi2Sr2Ca3Cu4Ox (2:2:3:4), and Bi2Sr2Ca4Cu5Ox (2:2:4:5). A single superconducting transition near 110 K has been observed in both resistive and magnetization shielding experiments for crystallized samples with 2:2:3:4 and 2:2:4:5 nominal compositions. Eutectic crystallization occurs during annealing of rapidly solidified glass samples. Both the 85-K and Ca2CuO3 phases cooperatively nucleate and grow from the amorphous matrix. The 110-K phase subsequently forms at the interfaces between the eutectic products, controlled by calcium and copper diffusion. A phase-change cycling has been observed, during which the 110-K phase increases in volume percent with increasing annealing time at 870 °C in calcium- and copper-rich samples. It then vanishes as annealing is prolonged at the same temperature. This behavior also occurs with different time periods depending on the initial calcium and copper composition of the samples. Microstructural changes associated with such cycling have also been observed. Also discussed are crystallization mechanisms, diffusion phenomena, and related superconducting properties.

Source-reported materials — not catalogue approval

Formula	Reported Tc (K)	Pressure (GPa)	Type
Bi2Sr2Ca2Cu3Ox Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	110	Pressure not reported	onset
Bi2Sr2Ca2Cu3Ox Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	110	Pressure not reported	onset
Bi2Sr2Ca3Cu4Ox Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	110	Pressure not reported	zero_resistance
Bi2Sr2Ca4Cu5Ox Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	100	Pressure not reported	zero_resistance
Bi2SrCuO4 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	20	Pressure not reported	unknown
Bi2Sr2CaCu2O Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	85	Pressure not reported	unknown
Bi2Sr2Ca2Cu3O Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	110	Pressure not reported	unknown