Influence of oxygen deficiency on the superconductive properties of grain-aligned YBa sub 2 Cu sub 3 O sub 7 minus. delta

Magnetically aligned samples of sintered YBa{sub 2}Cu{sub 3}O{sub 7{minus}{delta}} were used to test the effects of oxygen-deficiency {delta} (with {delta}{le}0.2) on the superconductive magnetization {ital M}, critical current density {ital J}{sub {ital c}}, irreversibility field {ital B}{sub irr}, upper critical field {ital H}{sub {ital c}2}, coherence length {xi}, condensation energy {ital F}{sub {ital c}}, penetration depth {lambda}, and related properties as a function of temperature {ital T} and applied field {bold H}{parallel}{bold c}. In selected cases, studies were also made with {bold H}{parallel}{ital ab}. The O content was monitored {ital in} {ital situ} by thermogravimetric analysis. The open porosity and granularity of the material allowed rapid and homogeneous oxygenation. We found no significant enhancement of intragrain {ital J}{sub {ital c}} with chain-site O defects. With few exceptions, maximum {ital J}{sub {ital c}} occurred at full oxygenation.