Phase development in the Bi2Sr2CaCu2Oy system. Effects of oxygen pressure

F. A. List, H. Hsu, O. B. Cavin, W. D. Porter, C. R. Hubbard, D. M. Kroeger

Research output: Contribution to journalArticlepeer-review

13 Scopus citations

Abstract

Studies have been undertaken using thermal analysis, in conjunction with high-temperature and room temperature X-ray diffraction, fraction, to elucidate phase relationships during thermal processing of thick films of initially phase pure Bi2Sr2CaCu2Oy (2212) on silver substrates in various oxygen-containing atmospheres (0.001 to 100% O2). Exothermic events on cooling at 10°C/min from a partially liquid state vary with oxygen partial pressure and can be grouped into three sets (I-III). Set I is prominent for 0.001% and 0.1% O2 in the range of 740-775°C and is believed to be associated with the crystallization of a Cu-free ∼ Bi5Sr3Ca1 oxide phase. Set II results from the crystallization of 2212; it is observed for p(O2)≥1.0% in the temperature range 800-870°C. Set III appears for 21% and 100% O2 in the temperature range 880-910°C, and its origin is not clear from the results of this study. Subsequent room temperature X-ray diffraction from these samples suggests that in general high oxygen partial pressures (100% O2) tend to favor the formation of Bi2Sr2CuO6 (2201), whereas low oxygen partial pressures (0.001-0.1% O2) lead to the formation of a Cu-free, Bi-Sr-Ca oxide phase. The 2212 phase forms at this cooling rate predominantly for intermediate oxygen partial pressures (7.6-21% O2). High-temperature X-ray diffraction during cooling (2°C/h) from the partially liquid state shows a pronounced dependence of the order of evolution of crystalline 2212 and 2201 phases on p(O2). For an oxygen partial pressure of 1.0% the formation of 2212 precedes that of 2201, whereas for 0.01% O2 2201 crystallizes at a higher temperature than 2212. The implications of these results pertaining to thermal processing of thick 2212 films are discussed.

Original languageEnglish
Pages (from-to)134-140
Number of pages7
JournalPhysica C: Superconductivity and its Applications
Volume202
Issue number1-2
DOIs
StatePublished - Nov 1 1992

Funding

~r Research funded by the Office of Transportation, Assistant Secretary for Conservation and Renewable Energy, as part of the High Temperature Materials Laboratory User Program, and jointly by the American Superconductor Corporation and the Superconducting Technology Program for Electric Energy Systems, Advanced Utility Concepts Division, Conservation and Renewable Energy, US Department of Energy, under con-tract DE-AC05-840R21400 with Martin Marietta Energy Sys-tems, Inc.

Fingerprint

Dive into the research topics of 'Phase development in the Bi2Sr2CaCu2Oy system. Effects of oxygen pressure'. Together they form a unique fingerprint.

Cite this