Ta离子辐照对YBa_(2)Cu_(3)O_(7–δ)的微观结构和载流特性的影响  

Effect of Ta irradiation on microstructures and current carrying properties of YBa_(2)Cu_(3)O_(7–δ)

作　　者：谷裕[1] 蔡传兵[1,2] 刘志勇 刘杰[3,4] 刘丽 黄荣铁[2] Yu Gu;Chuanbing Cai;Zhiyong Liu;Jie Liu;Li Liu;Rongtie Huang(Shanghai Key Laboratory of High Temperature Superconductors,Department of Physics,Shanghai University,Shanghai 200444,China;Shanghai Creative Superconductor Technologies Co.,Ltd,Shanghai 201401,China;Institute of Modern Physics,Chinese Academy of Sciences,Lanzhou 730000,China;School of Nuclear Science and Technology,University of Chinese Academy of Sciences,Beijing 100049,China)

机构地区：[1]上海大学物理系,上海市高温超导重点实验室,上海200444 [2]上海上创超导科技有限公司,上海201401 [3]中国科学院近代物理研究所,兰州730000 [4]中国科学院大学核科学与技术学院,北京100049

出　　处：《科学通报》2021年第31期3965-3972,共8页Chinese Science Bulletin

基　　金：中国科学院战略重点研究计划(XDB25000000);国家重点研发计划(2016YFF0101701);国家自然科学基金(51572165)资助。

摘　　要：高温超导YBa_(2)Cu_(3)O_(7–δ)(YBCO)涂层导体也称为第二代高温超导带材(2G-HTS带材),在能源、交通等领域具有广泛的应用前景.然而,其在强磁场下临界电流密度较低的问题严重限制了其应用,因此提升其磁通钉扎和在场载流能力是YBCO涂层导体的研究热点.本文利用1.9 GeV的Ta离子对YBCO带材进行辐照,研究了不同剂量的Ta离子辐照后YBCO带材的微观结构和载流特性变化.样品的场发射透射电子显微镜(field emission transmission electron microscope,FETEM)图像显示,辐照过程中高能^(181)Ta^(32+)离子在薄膜中形成了~10 nm尺寸的柱状缺陷,说明辐照后样品中产生了有效的钉扎中心.通过磁学测量系统(magnetic property measurement system,MPMS)对辐照样品的载流特性进行研究,发现当Ta离子剂量低于5.0×10^(10)ions/cm^(2)时,样品的临界转变温度T_(c,on)并无明显变化,但当剂量达到5.0×10^(10)ions/cm^(2)时,T_(c,on)减小了约0.6 K;当剂量高于1.0×10^(8)ions/cm^(2)时,由零场冷磁化强度随温度变化情况可知,辐照样品的超导抗磁相明显多于无辐照样品.同时,较高辐照剂量如5.0×10^(10)ions/cm^(2)YBCO样品的J_(c)较高,不同磁场下的J_(c)均得到了明显提升,30 K、1 T时的提升因子达到了3.8(提升因子定义为不同温度、外场下的J_(c)与77 K自场下J_(c)的比值),为同温度同场下无辐照样品的3倍.将临界电流密度J_(c)与磁场强度H的关系采用J_(c)∝H–β进行拟合,发现高剂量样品的磁通匹配场H*和表征随磁场衰减参数β增大了.此外,约化钉扎力密度标度关系显示,在低场下,样品中的钉扎类型在低辐照剂量下主要是面钉扎,当辐照剂量达到5.0×10^(10)ions/cm^(2)时开始向点缺陷钉扎类型转变,高场下则是所有样品都更符合面钉扎类型.High-temperature superconducting coated conductors(HTS CCs),which are based on epitaxial growth and biaxial texture technology of REBCO thin films,show excellent physical properties including high transition temperature T_(c,on),high irreversible field H_(irr),as well as high critical current density J_(c).However,YBa_(2)Cu_(3)O_(7–δ)(YBCO)has limited applications in a high magnetic field because of low critical current.Previous studies have shown that building smaller artificial pinning centers(APCs)is an effective way to increase the J_(c)of HTS CCs.Compared with the traditional chemical doping route,the particle irradiation method will result in various types and sizes of defects with uniform distribution by controlling the type,energy and dose of particles and keeping the original chemical ratio of the material.1.2μm YBCO superconducting layer was deposited on the LaMnO_(3) substrate of the samples by metal organic deposition(MOD)method.YBCO thin films were irradiated with 1.9 GeV Ta ions at room temperature and vacuum conditions.The microstructure of irradiated samples was systematically observed using a field emission transmission electron microscope(FETEM).The result shows that Ta ions do produce continuous columnar defects with uniform distribution in the superconducting layer of the YBCO films,and the size of the defects is about 10 nm.The basic superconducting parameters,such as T_(c,on)and J_(c),were measured using magnetic property measurement system(MPMS).The result shows the T_(c,on)of the pristine sample was 91.3 K.When the irradiation fluence was small,the T_(c,on)of the doped sample was basically unchanged.As the fluence reached 5.0×10^(10)ions/cm^(2),the T_(c,on)decreased by 0.6 K.In addition,the superconducting antimagnetic phases did not change much until the fluence exceeded 1.0×10^(8)ions/cm^(2).After the fluence exceeded 1.0×10^(8)ions/cm^(2),the superconducting antimagnetic phases increased obviously.They increased with the decrease of temperature as well.The result shows that J_(c)

关 键 词：高能Ta离子 YBa_(2)Cu_(3)O_(7-δ)高温超导涂层导体 辐照 钉扎缺陷 载流特性 

分 类 号：TM26[一般工业技术—材料科学与工程]