摘要
通过再冷压过程制备了单相(T_(co)=106K)Bi_(1.80)Pb_(0.34)Sr_(1.86)Ca_2Cu_3块材,和常规烧结的Bi系块材(SR)相比,再冷压块材(RCP)具有更明显的沿C轴取向和较高的体积密度。LN_2温度测量表明,零场下RCP块材的临界电流密度(J_C)普遍高于1000A/cm^2,最好的结果高达～4000A/cm^2,这远大于SR块材的J_C(～300A/cm^2)值。SR块材的J_C和磁场的关系遵从J_C～H^(-0.9),而对RCP块材J_C～H^(-0.56)。这表明前者是由于磁场破坏了颗粒间弱耦合的Josephson连接所致,而后者非常接近由磁通蠕动模型所预言的结果(J_C～H^(-0.5)),这意味着影响RCP块材J_C的主要原因是沿着类似于晶粒内部晶界的边界磁通蠕动。
The Bi1.8Pb0.84Sr1.88Ca2Cu3Oy bulk material of high-Tc single phase(T0 = 106K) was prepared by re-cold pressing process. The re-cold pressed Bi-based bulk material(RCP) has more obvious orientation along the c-axis and higher volume density compared with the sintered bulk material(SR). Measurements show that the transport current density Jc at 77K and zero field is generally higher than l000A/cm2 and the best result is as high as 4000A/cm2, which is far higher than that of SR(Jc-300A/cm2). A dependence of Jc-H-0.9 for SR is observed, indicating that the sharply decrease of Jc with field for SR is due to field-quenching of weak-coupling intergr ain Josephson junction. While for RCP, a dependence of Jc-H-0.58 is obtained, which is almost compatible with that predicted by flux creep model(Jc-H-0.5). This fact means that Jc of RCP is mainly limited by flux creep along the boundaries similar to the internal boundaries in grain.
出处
《低温与超导》
CAS
CSCD
北大核心
1991年第4期33-38,共6页
Cryogenics and Superconductivity
