Origin of a Bi-type modulated structure and its effects on superconductivity in Bi1.8Pb0.35Sr2Ca2Cu3Oy: Direct experimental observation

Chen Xianhui; Qian Yitai; Chen Zuyao; Lin Chun; Yang Li; Mao Ziqiang; Zhang Yuheng

doi:10.1103/PhysRevB.46.9181

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Origin of a Bi-type modulated structure and its effects on superconductivity in Bi1.8Pb0.35Sr2Ca2Cu3Oy: Direct experimental observation

Chen Xianhui, Qian Yitai, Chen Zuyao, Lin Chun, Yang Li, Mao Ziqiang, Zhang Yuheng

DOI 10.1103/PhysRevB.46.9181 · Physical Review B

T1

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Abstract

Samples with nominal composition Bi1.8Pb0.35Sr2Ca2Cu3Oy annealed in oxygen and nitrogen atmospheres at 500 and 750 °C are characterized by use of x-ray diffraction, magnetic measurements, oxygen-content determination, and electron diffraction. For samples annealed in an oxygen atmosphere, there exist two kinds of modulated structure: a Bi-type modulation and a Pb-type modulation. For samples annealed in N2 flow at 500 °C, Bi-type modulations disappear completely, although Pb-type modulations remain almost unchanged; however, for samples annealed in N2 flow at 750 °C, Pb-type modulations also disappear. It suggests that the Bi-type modulation originates from the extra oxygen in the Bi-O layers and the Pb-type modulation may arise not only from the excess oxygen but also from compositional modulations. Tc’s of these samples are found not to change significantly with annealing conditions and varying oxygen content, and it is concluded that the modulated structure is not crucial to the superconductivity.

Source-reported materials — not catalogue approval

Formula	Reported Tc (K)	Pressure (GPa)	Type
Bi1.8Pb0.35Sr2Ca2Cu3Oy Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	109	Pressure not reported	onset
Bi1.8Pb0.35Sr2Ca2Cu3Oy Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	107	Pressure not reported	onset
Bi1.8Pb0.35Sr2Ca2Cu3Oy Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	104	Pressure not reported	onset
Bi2Sr2CaCu2Oy Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	—	Pressure not reported	unknown
Bi2Sr2Ca2Cu3Oy Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	—	Pressure not reported	unknown