YBa_2Cu_3O_(7-x)c轴方向临界电流的测定

MEASUREMENT OF c-AXIS CRITICAL CURRENT DENSITY FOR YBa_2Cu_3O_(7-x)

本文测量了熔化织构法生长(MTG)的和通常烧结法制备的YBa_2Cu_3O_(7-x)块状样品的传输临界电流密度T_c以及磁场-样品不同取向的磁滞回线。MTG样品的J_c在78K和零场时达到3.5×10~4A/cm^2,实验提供了有力的证据表明如此高的J_c主要是由于块状样品内弱连接的消除,因为MTG块状样品的整体J_c与烧结样品颗粒内的J_c几乎相同。从磁滞回线中我们估算出了垂直于a-b平面流动(沿c轴方向)的J_c比平行于a-b平面流动的J_c约小一个数量级。

Transport critical current density Jc and hysteresis loop at different field-sample orientations were measured for both melt-textured growth (MTG) and sintered YBa2Cu3O_y (YBCO) sample. Very high Jc (78K, 0 Oe) of 3.5×104 A/cm2 has been obtained for the MTG YBCO sample. The experimental results show strong evidence of that the high Jc in MTG YBCO results mainly from the significant reduction of weak links because the bulk Jc for MTG sample are almost the same as the intragrain Jc for sintered sample. We also show that the Jc parallel to a-b plane is about an order of magnitude higher than that normal to a-b plane (J_(c11)≈ 0J_(c1)).