The effect of the 2D internal strain state on the critical current in GdBCO coated conductors
The effect of the 2D internal strain state on the critical current in GdBCO coated conductors
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DOI：
10.1088/0953-2048/25/5/054014
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发表时间：
2012-05-01
影响因子：
3.6
通讯作者：
Saitoh, Takashi
中科院分区：
文献类型：
--
作者：
Sugano, Michinaka;Machiya, Shutaro;Saitoh, Takashi
报道了REBa_2Cu_3O_（7-δ）（REBCO）涂层导体的临界电流（I-c）随应变的可逆变化。在这项研究中，I-c的应变灵敏度进行了比较，GdBCO涂层导体具有不同的晶体取向。在77 K的拉伸和弯曲试验中，[110]方向平行于带长的GdBCO薄膜（Gd-F）的应变灵敏度非常小，而[100]或[010]方向平行于带长的GdBCO薄膜（Gd-I）的I-c应变依赖性要强得多。为了比较基于内部应变的I-c的应变灵敏度，通过采用使用同步辐射的衍射技术来评估复合导体中的GdBCO膜的晶格应变。晶格应变沿沿着a-和b-轴的正交域所产生的GdBCO膜的孪晶结构。一个明显的差异，在2D应变状态，取决于晶体取向被揭示为GdBCO涂层导体。在Gd-I中，在拉伸载荷下，沿着轴向和横向方向的晶格应变分别为拉伸和压缩，即二维内部应变状态是各向异性的。另一方面，在Gd-F中确认了几乎各向同性的2D应变状态。此外，Gd-F中沿晶轴的应变分量沿着比Gd-I中的轴向应变分量小得多。这种内部应变状态的差异归因于具有不同晶体取向的GdBCO涂覆导体之间的应变灵敏度的差异。根据两个导体的应变灵敏度和内部应变的测量结果，讨论了应变分量沿着a轴和b轴对I-c的贡献。
A reversible effect of strain on the critical current (I-c) has been reported for REBa2Cu3O7-delta (REBCO) coated conductors. In this study, the strain sensitivity of I-c was compared for GdBCO coated conductors with different crystal orientations. Extremely small strain sensitivity was confirmed from tensile and bending tests at 77 K for a GdBCO film with the [110] direction parallel to the tape length (Gd-F), while a GdBCO film with the [100] or [010] direction parallel to the tape length (Gd-I) has much stronger strain dependence of I-c. To compare the strain sensitivity of I-c based on internal strain, the lattice strain was evaluated for a GdBCO film in a composite conductor by employing a diffraction technique using synchrotron radiation. The lattice strain was determined along both the a- and b-axes for the orthogonal domains that are generated by the twin structure of GdBCO film. A distinct difference in the 2D strain state that depended on the crystal orientation was revealed for the GdBCO coated conductors. In Gd-I, the lattice strains along the axial and lateral directions are tensile and compressive under tensile loading, respectively, that is, the 2D internal strain state is anisotropic. On the other hand, an almost isotropic 2D strain state was confirmed in Gd-F. In addition, the strain components along the crystal axes in Gd-F are much smaller than the axial strain components in Gd-I. This difference in the internal strain state is attributed to the difference in strain sensitivity between the GdBCO coated conductors with different crystal orientations. The contributions of the strain components along the a- and b-axes to I-c are discussed on the basis of the measured strain sensitivities and internal strains for two conductors.