Magnetization behavior of RE123 bulk magnets bearing twin seed-crystals in pulsed field magnetization processes
Magnetization behavior of RE123 bulk magnets bearing twin seed-crystals in pulsed field magnetization processes
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脉冲场磁化过程中带有孪晶的 RE123 块体磁体的磁化行为
DOI：
10.1088/0953-2048/29/2/024003
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发表时间：
2016
影响因子：
3.6
通讯作者：
K. Yokoyama
中科院分区：
文献类型：
--
作者：
T. Oka;T. Miyazaki;J. Ogawa;S. Fukui;T. Sato;K. Yokoyama
采用冷籽晶法在MgO衬底上制备了由Nd-Ba-Cu-O薄膜组成的单晶或双晶种，制备了熔融织构的Y-Ba-Cu-O高温超导块材磁体。在35 K下进行脉冲磁场磁化期间和之后，精确地评估了磁通量渗透到各向异性生长的块状磁体中的行为。这些晶种被放置在前体的顶表面上，以在熔融过程中生长大晶粒。虽然我们知道磁通量的运动受到限制的增强钉扎效应的温度范围低于77 K，我们观察到，磁通入侵发生在施加的磁场为3.3 T时，使用的孪生种子。这肯定低于采用单种子时的3.7T。这意味着磁通量能够比单种子磁体更容易地侵入双种子磁体。孪晶籽晶根据平行于籽晶排和垂直于籽晶排的不同晶粒生长方向，形成不同的晶粒生长区域，即窄晶区和宽晶区。侵入磁通量的测量表明，磁通量侵入样品从宽GSR之前窄GSR。这表明，这种各向异性的晶粒生长导致不同的分布的钉扎中心，Jc值的变化，并形成优先路径的入侵磁通。使用较低的外加磁场肯定有助于降低PFM过程中的热生成，这反过来又导致了增强的捕获磁通量。
Melt-textured Y-Ba-Cu-O high temperature superconducting bulk magnets were fabricated by the cold seeding method with using single or twin-seed crystals composed of Nd-Ba-Cu-O thin films on MgO substrates. The behavior of the magnetic flux penetration into anisotropic-grown bulk magnets thus fabricated was precisely evaluated during and after the pulsed field magnetization operated at 35 K. These seed crystals were put on the top surfaces of the precursors to grow large grains during the melt-processes. Although we know the magnetic flux motion is restricted by the enhanced pinning effect in temperature ranges lower than 77 K, we observed that flux invasion occurred at applied fields of 3.3 T when the twin seeds were used. This is definitely lower than those of 3.7 T when the single-seeds were employed. This means that the magnetic fluxes are capable of invading into twin-seeded bulk magnets more easily than single-seeded ones. The twin seeds form the different grain growth regions, the narrow-GSR (growth sector region) and wide-GSR, according to the different grain growth directions which are parallel and normal to the rows of seed crystals, respectively. The invading flux measurements revealed that the magnetic flux invades the sample from the wide-GSR prior to the narrow-GSR. It suggests that such anisotropic grain growth leads to different distributions of pinning centers, variations of J c values, and the formation of preferential paths for the invading magnetic fluxes. Using lower applied fields definitely contributed to lowering the heat generation during the PFM process, which, in turn, led to enhanced trapped magnetic fluxes.
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脉冲场磁化过程中和之后各向异性生长的 Y-Ba-Cu-O 体超导体的磁通量捕获
DOI：
10.1088/1742-6596/507/1/012039
发表时间：
2014
期刊：
Journal of Physics: Conference Series
影响因子：
--
作者：
T. Oka;Y. Yamada;T. Horiuchi;J. Ogawa;S. Fukui;T. Sato;K. Yokoyama;M. Langer
通讯作者：
M. Langer
脉冲场磁化过程中空洞减少的高温超导块体磁体的场俘获特性
DOI：
10.1088/1742-6596/400/2/022089
发表时间：
2012
期刊：
Journal of Physics: Conference Series
影响因子：
--
作者：
T. Oka;H. Seki;D. Ishiduka;J. Ogawa;S. Fukui;T. Sato;K. Yokoyama;A. Murakami
通讯作者：
A. Murakami
Dy123块体磁体在迭代脉冲场磁化过程中的磁通侵入行为和温度变化
影响因子：
1.7
作者：
T. Oka;D. Ishiduka;J. Ogawa;S. Fukui;Takashi Sato;K. Yokoyama;A. Murakami;H. Stopfel
通讯作者：
H. Stopfel
脉冲场侵入由两种具有不同籽晶位置和数量的种子生长的高温超导块体磁体
DOI：
10.1016/j.phpro.2014.09.021
发表时间：
2014
期刊：
Physics Procedia
影响因子：
--
作者：
T. Oka;Y. Yamada;T. Horiuchi;J. Ogawa;S. Fukui;Takashi Sato;K. Yokoyama;M. Langer
通讯作者：
M. Langer
影响因子：
3.6
作者：
Durrell, J. H.;Dennis, A. R.;Cardwell, D. A.
通讯作者：
Cardwell, D. A.