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采用熔融织构生长法,制备了多晶YBCO超导体。X光衍射图象表明,晶体按垂直于c轴的择优取向排列。这种排列规则的层状结构有利于电流传输,并为77K,0T下的低温测试结果所证实。在0～7T外场下的I-V测试曲线证明:熔融织构生长工艺使普通粉末烧结样品中存在的弱连接问题获得了重大改善。研究了三种不同的原始粉末对熔融生长样品J_c的影响;做出了以三种不同粉末为原料的熔融生长样品的临界电流密度-熔融温度对比曲线;用X光衍射仪对样品做了相分析;用扫描电镜对样品进行了断口形貌观察和对比。采用合适的工艺制度制备的样品,在0T和1T下,J_c值分别达到12200 A/cm~2以上和4200 A/cm~2以上(1μV/cm,77K)。
The polycrystalline YBCO superconductor was prepared by melt texture growth method. X-ray diffraction images show that the crystals are arranged in a preferred orientation perpendicular to the c-axis. The layered structure of this arrangement is conducive to the current transmission, and to 77K, 0T under the low temperature test results confirmed. The I-V test curve at 0 ~ 7T external field proves that the melt textured growth process has greatly improved the weak connection problems existing in ordinary powder sintered samples. The effects of three different primary powders on the melt growth samples Jc were studied. The critical current density-melting temperature comparison curves of the melt growth samples with three different powders as raw materials were made. The samples were characterized by X-ray diffractometry Analysis of the samples by scanning electron microscopy of the fracture morphology and contrast. The samples prepared with the proper process system had Jc values above 12200 A / cm ~ 2 and 4200 A / cm ~ 2 (1μV / cm, 77K) at 0T and 1T, respectively.