The results of electrical transport and AC susceptibility measurements performed with the goal of studying the superconducting and normal state electrical properties of polycrystalline samples of $\rm YBa\sb2Cu\sb3O\sb{7-\delta}$ and $\rm Ag/YBa\sb2Cu\sb3O\sb{7-\delta}$ are reported. I-V characteristics and AC susceptibility for $\approx$2 mm diameter sintered polycrystalline $\rm YBa\sb2Cu\sb3O\sb{7-\delta}$ pellets are studied at selected magnetic fields $0.1\le H\le 80.9$ G and for $80\le T\le 92$ K. Temperature dependent changes in I-V isotherms near the superconducting transition are consistent with predictions of critical scaling associated with a superconducting phase transition. AC susceptibility measurements reveal a variety of interesting phenomena, and in particular provide evidence that these materials are gauge glass granular superconductors. Magnetic field and temperature dependent changes in the I-V characteristics of $\approx$15 $\mu$m diameter $\rm Ag/YBa\sb2Cu\sb3O\sb{7-\delta}$ fibers are studied for $4\le T\le 86$ K, for $0.5\le H\le 9000$ G, and for $1\le J\le 10\sp4$ A/cm$\sp2.$ These measurements reveal a variety of quite different regions of superconducting behavior that are all consistent with a system of weakly coupled superconducting grains.
| Identifer | oai:union.ndltd.org:UMASS/oai:scholarworks.umass.edu:dissertations-8444 |
| Date | 01 January 1992 |
| Creators | Tiernan, William Michael |
| Publisher | ScholarWorks@UMass Amherst |
| Source Sets | University of Massachusetts, Amherst |
| Language | English |
| Detected Language | English |
| Type | text |
| Source | Doctoral Dissertations Available from Proquest |
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