Defect evolution in Y_0.5Gd_0.5Ba₂Cu₃O_{7–<i>δ</i>} superconducting layer irradiated by H⁺ ions

Abstract

&lt;sec&gt;In order to further improve the superconducting current carrying capacity of RE-Ba-Cu-O coated conductor under the action of strong magnetic field, ion irradiation is used to generate the pinning centers of introduced magnetic flux in the RE-Ba-Cu-O coated conductor. In this work, the H&lt;sup&gt;+&lt;/sup&gt;-ion irradiation of second-generation high-temperature superconductor RE-Ba-Cu-O strip is carried out by using the 320 kV high charge state ion synthesis research platform. Doppler broadened slow positron beam analysis combined with Raman spectroscopy is used to measure the change of microstructure in Y&lt;sub&gt;0.5&lt;/sub&gt;Gd&lt;sub&gt;0.5&lt;/sub&gt;Ba&lt;sub&gt;2&lt;/sub&gt;Cu&lt;sub&gt;3&lt;/sub&gt;O&lt;sub&gt;7-&lt;i&gt;δ&lt;/i&gt; &lt;/sub&gt;(YBCO)sample irradiated by H&lt;sup&gt;+&lt;/sup&gt; ions in a range of 5.0×10&lt;sup&gt;14&lt;/sup&gt;–1.0×10&lt;sup&gt;16&lt;/sup&gt; ions/cm&lt;sup&gt;2&lt;/sup&gt;. The positron annihilation parameters in YBCO before and after irradiation are analyzed. It is found that after 100 keV H&lt;sup&gt;+&lt;/sup&gt; ion irradiation, a large number of defects including vacancies, vacancy groups or dislocation groups are produced in the superconducting layer.&lt;/sec&gt;&lt;sec&gt;The larger the irradiation dose, the more the produced vacancy type defects are and the more complex the defect types, and the annihilation mechanism of positrons in the defects changes. Raman spectroscopy results show that with the increase of H&lt;sup&gt;+&lt;/sup&gt; ion irradiation dose, the oxygen atoms in the coating rearrange, the plane spacing increases, the orthogonal phase structure of the coating is destroyed, and the degree of order decreases. The defects produced by such an ion irradiation lay a foundation for the introduction of flux pinning centers. Further research can be carried out in combination with X-ray diffractometer, transmission electron microscope, superconductivity and other testing methods to provide theoretical and practical reference for the optimization of material properties.&lt;/sec&gt;

Effect of doping on evolution of He⁺ion irradiation defects and superconductivity in EuBa₂Cu₃O_7–δ superconducting strips

“…对两种带材辐照前后的样品进行了拉曼光谱测试, 以考察低、高(分别为5×10 14 和5×10 16 ions/cm 2 ) [41] , 即 115 cm -1 处 的 [42] . 在 剂 量 为 5×10 14 ions/cm 2 时, 两种带材的超导特征峰峰位和峰形均 无明显变化, 这表明该剂量下, 辐照缺陷对两种带 材晶体结构的影响较小; 剂量增至5×10 16 ions/cm 2 时, 两种带材的超导特征峰消失、出现了极高的阳 离子无序(CD)峰位, 且峰形极宽, 这表明该剂量下 辐照缺陷使得超导层晶格高度无序, 极大破坏了超 导电流的传导结构, 进而损害了带材的超导电性 [43] . 造成的逃逸型氧空位为He扩散提供通道, 加速其 形成He-空位复合体 [44] , 因此辐照空位形成能垒和 浓度决定了超导层中氦泡的尺寸和密度 [45] .…”