DC and AC susceptibility study of sol–gel synthesized Bi2Sr2CaCu2O8+δ superconductor
DC and AC susceptibility study of sol–gel synthesized Bi2Sr2CaCu2O8+δ superconductor
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DOI：
10.1016/j.ceramint.2012.07.038
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发表时间：
2013-03
影响因子：
5.2
通讯作者：
D. Sharma;Ranjan Kumar;V. Awana
中科院分区：
文献类型：
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作者：
D. Sharma;Ranjan Kumar;V. Awana
研究了溶胶-凝胶法合成的Bi_2Sr_2CaCu_2O_（8 +δ）（Bi-2212）多晶样品在不同烧结温度下的直流磁化率沿着变化以及交流磁化率的幅值和频率特性。特别是，它表明，磁化率技术是一个有效的工具来表征高温超导体的颗粒特性。在Bean临界状态模型的框架内讨论了结果，确定了临界电流密度的场和温度依赖性。磁通钉扎力密度的计算和钉扎机制普遍存在于II型超导体的可能性进行了研究。磁通蠕变激活能是根据交流磁化率的频率依赖性所表现出的涡旋动力学来确定的。由于多晶样品是颗粒状的性质，我们计算了晶粒体积分数和分离的贡献，晶粒和矩阵的磁化率从总测量的交流磁化率。我们确定，在烧结温度的增加不仅改变晶粒形态，但影响超导性能显着，验证晶界对所研究的Bi-2212超导体的超导性能的影响。
We study DC susceptibility along with amplitude and frequency dependence of AC susceptibility of sol–gel synthesized polycrystalline samples of Bi2Sr2CaCu2O8+δ(Bi-2212) sintered at different temperatures. In particular, it is demonstrated that susceptibility techniques are an effective tool to characterize granular characteristics of high temperature superconductors. The results are discussed in the framework of Bean's critical state model whence the field and temperature dependence of critical current density is determined. Flux pinning force density is calculated and possibility of the pinning mechanisms prevalent in type II superconductors are investigated. Flux creep activation energy is determined in the light of vortex dynamics exhibited by frequency dependence of AC susceptibility. Since polycrystalline samples are granular in nature, we calculated grain volume fraction and separated the contribution of grain and matrix susceptibility from total measured AC susceptibility. We establish that increase in the sintering temperature not only changes the grain morphology but affects the superconducting properties significantly, validating the impact of grain boundaries on superconducting performance of studied Bi-2212 superconductor.