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首页> 外文期刊>Journal of Materials Engineering and Performance >Amorphous Superconducting Transformation in Bismuth-Base High-T_c Superconducting Rods
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Amorphous Superconducting Transformation in Bismuth-Base High-T_c Superconducting Rods

机译：铋基高T_c超导棒中的非晶态超导转变

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The transformation of high-resistivity amorphous (Bi_(1.68)Pb_(0.32))Sr_(1.75)Ca_(1.85)Cu_(2.85)O_y, and (Bi_(1.6)Pb_(0.4))Sr_(1.7)Ca_(2.3)Cu_3O_y to superconductive materials has been characterized by structural, thermochemical, transport, and scanning electron microscope measurements. X-ray powder diffraction confirmed that rapid solidification of Bi-Pb-Sr-Ca-Cu-O_y yields amorphous material. In further heat treatments, sequential crystallization of three phases was identified. Differential scanning calorimetry indicated an exothermic crystallization peak at 520 deg C with corresponding enthalpy of 62 J/g. Scanning electron microscopy studies revealed that the grain size increases with sintering time and that the formation mechanism in the interior of the bulk is different from that at the surface of the superconducting glass ceramic rods. Thermal cycling of the insulating glass to a temperature above that required for crystallization results in a transformation from an insulating to a superconducting material with a T_c (R = 0) of 105 K. It was also shown that the glass ceramic rods obtained by reheating glass rods to 850 deg C for 120 fa have a T_c (R = 0) of 105 K, whereas the disk specimens obtained by reheating the powdered glass compacts in the same way do not exhibit superconductivity above 85 K. This difference in superconductivity between the specimens is discussed in terms of the crystallization process and the amount of oxygen absorption of the specimens during heating.
机译：高电阻率非晶态（Bi_（1.68）Pb_（0.32））Sr_（1.75）Ca_（1.85）Cu_（2.85）O_y和（Bi_（1.6）Pb_（0.4））Sr_（1.7）Ca_（2.3）的相变Cu_3O_y对超导材料的特征在于结构，热化学，传输和扫描电子显微镜的测量。 X射线粉末衍射证实，Bi-Pb-Sr-Ca-Cu-O_y的快速凝固会产生非晶态材料。在进一步的热处理中，确定了三相的顺序结晶。差示扫描量热法表明在520℃有放热结晶峰，相应的焓为62J / g。扫描电子显微镜研究表明，晶粒尺寸随烧结时间的增加而增大，并且在内部的形成机理与在超导玻璃陶瓷棒表面的形成机理不同。绝缘玻璃的热循环至高于结晶所需温度的温度导致从绝缘材料转变为T_c（R = 0）为105 K的超导材料。还显示了通过对玻璃进行重新加热而获得的玻璃陶瓷棒到850摄氏度，120 fa的棒材的T_c（R = 0）为105 K，而通过以相同方式对粉末状玻璃粉坯进行再加热而获得的圆盘样品在85 K以上没有超导电性。样品之间的超导电性差异讨论了结晶过程和加热过程中样品的氧气吸收量。

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