Hostname: page-component-77c89778f8-n9wrp Total loading time: 0 Render date: 2024-07-22T21:19:25.221Z Has data issue: false hasContentIssue false

Some Observations on the Measurement of Transport Critical Current Density in Bulk Ceramic Superconductive Wire

Published online by Cambridge University Press:  26 February 2011

S. Samajdar
Affiliation:
Plasticity Laboratory, Mechanical Engineering Department, University of Nevada, Reno, NV 89557–0030.
Shyam K. Samanta
Affiliation:
Plasticity Laboratory, Mechanical Engineering Department, University of Nevada, Reno, NV 89557–0030.
Get access

Abstract

The transition temperature and the critical current density of a bulk YBa2Cu3O7−x-Ag microcomposite superconductive wire, prepared by powder processing followed by warm extrusion, have been measured employing the standard AC four probe technique. Measurements were performed, at 15K and zero applied field, with varying distance between the voltage contacts, while the current contacts remained a constant distance apart. It is observed that the resistance-temperature behavior remained identical in all the cases. Interestingly, the critical current density, determined from the experimentally recorded current-voltage characteristic by applying a constant electric field criterion, is seen to increase significantly, smoothly and steadily with increasing voltage tap length. However, the critical current density remains virtually unchanged if a constant voltages criterion is applied for its determination. This paradoxical dependence of critical current density, a material property, on measurement length has been explained with the help of a simple theoretical treatment, taking into account the nature of current-voltage chracteristics as well as the phenomenon of current transfer through the metallic to the superconducting ceramic phase. It is suggested that the constant electric field criterion may not be an appropriate one to use in the evaluation of critical current density of metal-ceramic superconductive composites.

Type
Research Article
Copyright
Copyright © Materials Research Society 1992

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)

References

REFERENCES

1. Annual book of ASTM standards 02.03. B 714–82 (1988).Google Scholar
2. Goodrich, L. F. and Fickett, F. R., Cryogenics 22, 225 (1982).Google Scholar
3. Calabrese, Joseph J., Ph. D. thesis, The Ohio State University, 1989.Google Scholar
4. Samanta, Shyam K. and Samajdar, S., Annals of the CIRP 41/1, 1992 (in print).Google Scholar
5. Ekin, J. W., J. Appl. Phys. 49, 3406 (1978).Google Scholar
6. Otto, A. J. and Vander Sande, J. B., Physica C 159, 357 (1989).Google Scholar
7. Prester, M., Babic, E., Biskup, N., Leising, G., Biebernik, K. and Kahlert, H., 1991 (private communication).Google Scholar