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Effect of shock pressure on the structure and superconducting properties of y-ba-cu-o in explosively fabricated bulk metal-matrix composites
| Content Provider | NASA Technical Reports Server (NTRS) |
|---|---|
| Author | Murr, L. E. Pradhan, M. Schoenlein, L. H. Niou, C. S. |
| Copyright Year | 1990 |
| Description | While it is now well established that copper-oxide-based powder, or virtually any other ceramic superconductor powder, can be consolidated and encapsulated within a metal matrix by explosive consolidation, the erratic superconductivity following fabrication has posed a major problem for bulk applications. The nature of this behavior was found to arise from microstructural damage created in the shock wave front, and the residual degradation in superconductivity was demonstrated to be directly related to the peak shock pressure. The explosively fabricated or shock loaded YBa2Cu3Ox examples exhibit drastically altered rho (or R) - T curves. The deterioration in superconductivity is even more noticeable in the measurement of ac magnetic susceptibility and flux exclusion or shielding fraction which is also reduced in proportion to increasing peak shock pressure. The high-frequency surface resistance (in the GHz range) is also correspondingly compromised in explosively fabricated, bulk metal-matrix composites based on YBa2Cu3O7. Transmission electron microscopy (including lattice imaging techniques) is being applied in an effort to elucidate the fundamental (microstructural) nature of the shock-induced degradation of superconductivity and normal state conductivity. One focus of TEM observations has assumed that oxygen displaced from b-chains rather than oxygen-vacancy disorder in the basal plane of oxygen deficient YBa2Cu3Ox may be a prime mechanism. Shock-wave displaced oxygen may also be locked into new positions or interstitial clusters or chemically bound to displaced metal (possibly copper) atoms to form precipitates, or such displacements may cause the equivalent of local lattice cell changes as a result of stoichiometric changes. While the shock-induced suppression of T(sub c) is not desirable in the explosive fabrication of bulk metal-matrix superconductors, it may be turned into an advantage if the atomic-scale distortion can be understood and controlled as local flux pinning sites. |
| File Size | 211960 |
| Page Count | 4 |
| File Format | |
| Alternate Webpage(s) | http://archive.org/details/NASA_NTRS_Archive_19900018488 |
| Archival Resource Key | ark:/13960/t2h759z8f |
| Language | English |
| Publisher Date | 1990-04-01 |
| Access Restriction | Open |
| Subject Keyword | Composite Materials Magnetic Flux Stoichiometry Pressure Effects Superconductivity Imaging Techniques Powder Particles Ceramics Electron Microscopy Precipitates Shock Waves Transmission Electron Microscopy Flux Pinning Magnetic Permeability Barium Oxides Metal Matrix Composites Microstructure Copper Oxides Yttrium Oxides Ntrs Nasa Technical Reports Server (ntrs) Nasa Technical Reports Server Aerodynamics Aircraft Aerospace Engineering Aerospace Aeronautic Space Science |
| Content Type | Text |
| Resource Type | Article |
