Protocols and methodologies for acquiring and analyzing critical-current versus longitudinal-strain data in Bi2Sr2CaCu2O8+x wires
- Florida State University, Tallahassee, FL (United States)
In the literature on Bi2Sr2CaCu2O8+x (Bi-2212) superconducting wires, it is evident that measurement protocols for transport critical-current Ic versus longitudinal strain epsilon and definitions of the so-called 'strain limit' are generally dissimilar. Yet, values obtained for the 'strain limit' are frequently assimilated to being those of the irreversible strain limit ϵirr, regardless of the Ic degradation-criterion used to define it. In effect, ϵirr should correspond specifically to the Ic(ϵ) irreversibility onset, where crack formation in Bi-2212 filaments presumably starts. Because Ic(ϵ) degradation remains progressive over a fairly wide strain range beyond ϵirr, the different Ic degradation-criteria in use do not yield to the same result and, thus, are not equivalent from metrology perspective. Indeed, in studying densified samples of a modern Bi-2212 round wire, we found ϵirr ≈ 0.4% and ϵ5% ≈ 0.6% (ϵ5% being the strain where Ic degrades by 5%). In this paper, we outline and suggest Ic(ϵ)-measurement protocols and data-analysis methodologies in the hope to converge the various approaches taken for studying Bi-2212 strain properties and, thus, remove related result discrepancies. A unified approach would enable more objective data comparisons among laboratories and among different Bi-2212 conductors. It would pave the way for more rigorous studies of effects potentially associated with wire design, powder, heat treatments, and other such parameters on the conductor's strain properties.
- Research Organization:
- Florida State Univ., Tallahassee, FL (United States)
- Sponsoring Organization:
- USDOE Office of Science (SC), High Energy Physics (HEP); National Science Foundation (NSF); USDOE
- Grant/Contract Number:
- SC0017657; DMR-1644779; DMR-2128556
- OSTI ID:
- 2481137
- Alternate ID(s):
- OSTI ID: 2479938; OSTI ID: 2497800
- Journal Information:
- Superconductor Science and Technology, Vol. 38, Issue 1; ISSN 0953-2048
- Publisher:
- IOP PublishingCopyright Statement
- Country of Publication:
- United States
- Language:
- English