Flux pinning by Al-based nanoparticles embedded in YBCO: A transmission electron microscopic study
✍ Scribed by F. Ben Azzouz; M. Zouaoui; A. Mellekh; M. Annabi; G. Van Tendeloo; M. Ben Salem
- Publisher
- Elsevier Science
- Year
- 2007
- Tongue
- English
- Weight
- 852 KB
- Volume
- 455
- Category
- Article
- ISSN
- 0921-4534
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✦ Synopsis
A series of YBa 2 Cu 3 O y (YBCO) samples with small amounts (0-0.6 wt.%) of nanosized alumina particles (50 nm) are synthesized in air by solid state reaction. The microstructure has been characterized by transmission electron microscopy (TEM) and the critical current density J c has been measured by the standard four-probe method in the applied magnetic field at 77 K. TEM and energy dispersive X-ray spectroscopy (EDS) analysis have shown that alumina reacts with the YBCO matrix to form nanometric aluminium-rich inhomogeneities intergrown within the YBCO superconducting matrix. These inhomogeneities reduce the onset transition temperature T onset c and the zero resistance temperature T c . In spite of the monotonic decrease of the superconducting temperature T c with increasing alumina addition, the J c (H) behaviour is remarkably improved. The characteristic behaviour of J c can be explained in terms of the counterbalance of two effects simultaneously caused by the nanometric alumina addition in the system. One effect is the formation of the Al-rich nanometric inhomogeneities relevant for the flux pinning, and the other effect is the reduction of matrix superconducting volume, which is reflected by a decrease of the critical current density J c at zero applied magnetic field.