【摘要】 磁化测量表明,在烧结Bi_1.8Pb_0.34Sr_1.86Ca₂O_y超导块材样品中存在两种不同类型的 晶粒间边界:一种晶粒间边界对磁通线几乎没有钉扎力;而另一种则在低场范围内能捕获一些磁通线,并在此处维持一定的钉扎电流。当外加磁场减小到零时,大部分剩余磁矩都来源于晶粒边界。经过冷压后的样品在低场下的磁滞回线面积和剩余磁矩都显著地增加。冷压使得晶粒取向并使样品致密,从而导致样品中超导颗粒间的耦合增强。在77K零场和1kOe时,冷压样品的传输临界电流密度J_e分别为1040A/cm²和150A/cm²。讨论了冷压样品沿晶粒间边界的磁通蠕动以及钉扎势U₀。更多还原

【Abstract】 The magnetization measurement shows that there are two kinds of different intergrain boundaries in the sintered Bi1.8 Pb0.34 SrL 86 Ca2 CujOy, superconductors. One has nearly no pinning force for flux line, the other can trap some flux line in the low field range where a pinning current may be sustained. When the applied field is removed, most of the remanent magnetization comes from the intergrain boundaries. The area of hysteresis loop at low field and the remanent magnetization for the cold-pressed bulk samples are significantly increased. Cold pressing results in aligning the grain orientation and raising the packing density, both of which enhanced intergrain coupling. The Jc value of 1040 A/cm2 at H = 0 and 150 A/cm2 at H = 1 kOe are obtained. The flux creep along the intergrain boundaries and the pinning potential energy U0 for the cold-pressed samples are also discussed.更多还原