Flux pinning force in bulk MgB2 with variable grain size
Flux pinning force in bulk MgB2 with variable grain size
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DOI：
10.1103/physrevb.75.134515
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发表时间：
2007-04-01
影响因子：
3.7
通讯作者：
Abell, J. S.
中科院分区：
文献类型：
--
作者：
Martinez, E.;Mikheenko, P.;Abell, J. S.
本文报道了不同晶粒度的块体镁的磁通钉扎力随温度和磁场的变化关系。样品是由先进的方法制备的，允许将第二相的孔隙率、杂质和夹杂物的影响降至最低。分析了颗粒连通性、磁通蠕变现象和颗粒尺寸对临界电流密度和磁通钉扎曲线的影响。我们对一系列样品的钉扎力的场依赖关系与考虑了颗粒尺寸影响的理论模型的预测进行了比较。汉普希尔和琼斯提出的晶界钉扎机制在定性上是一致的。C21,419(1987)]和实验观察到的块体MgB_2钉扎力与颗粒尺寸的关系。
We report temperature and magnetic-field dependence of flux pinning force in bulk MgB2 with variable grain size. The samples are prepared by advanced methods, allowing minimizing effects of porosity, impurities, and inclusions of secondary phases. The effects of grain connectivity, flux-creep phenomena, and grain size on critical current density and flux pinning curves are analyzed. We have compared the field dependence of the pinning force for a range of samples with the predictions of theoretical models accounting for the effect of the grain size. There is qualitative agreement between grain-boundary pinning mechanism proposed by Hampshire and Jones [J. Phys. C 21, 419 (1987)] and the experimentally observed grain-size dependence of pinning force in bulk MgB2.