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首页> 外文期刊>Journal of materials science >Role of diffusion-annealing temperature on the microstructural and superconducting properties of Cu-doped MgB_2 superconductors
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Role of diffusion-annealing temperature on the microstructural and superconducting properties of Cu-doped MgB_2 superconductors

机译：扩散退火温度对掺Cu MgB_2超导体微结构和超导性能的影响

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摘要

This study deals with not only investigate the effect of the copper diffusion on the microstructural and superconducting properties of MgB_2 superconducting samples employing dc resistivity as a function of temperature, scanning electron microscopy (SEM) and X-ray diffraction (XRD) measurements but also calculate the diffusion coefficient and the activation energy of copper for the first time. Electrical-resistivity measurements indicate that both the room-temperature resistivity value and zero resistivity transition temperatures (T_c) increase with increasing the diffusion-annealing temperature from 650 to 850 ℃. SEM measurements show that not only the surface morphology and grain connectivity improve but also the grain size of the samples increases with the increase in the diffusion-annealing temperature up to 850 ℃. As for the XRD results, all the samples contain the MgB_2 phase only and exhibit the polycrystalline superconducting phase with more intensity of diffraction lines, leading to the increasement in the lattice parameter a and c. Additionally, the diffusion coefficient is observed to increase from 6.81 × 10~(-8) to 4.69 × 10~(-7) cm~2 s~(-1) as the diffusion-annealing temperature increases, confirming that the Cu diffusion at lower temperatures is much less significant. Temperature dependence of the Cu diffusion coefficient is described with the aid of the Arrhenius relation D = 3.75 × 10~(-3) exp (-1.15 ± 0.10 eV/k_Β T) and the corresponding activation energy of copper in MgB_2 system is found to be about 1.15 eV. The possible reasons for the observed improvement in microstructural and superconducting properties of the samples due to Cu diffusion are also discussed.
机译：这项研究不仅研究了铜扩散对MgB_2超导样品的微结构和超导性能的影响，还使用了直流电阻率作为温度，扫描电子显微镜（SEM）和X射线衍射（XRD）测量的函数，并且还计算了铜的扩散系数和活化能。电阻率测量表明，室温电阻率值和零电阻率转变温度（T_c）随扩散退火温度从650℃增加到850℃而增加。 SEM测量结果表明，随着扩散退火温度升高至850℃，样品的表面形貌和晶粒连通性均得到改善，样品的晶粒尺寸也随之增大。至于X射线衍射结果，所有样品仅含有MgB_2相，并表现出具有更多衍射线强度的多晶超导相，从而导致晶格参数a和c的增加。另外，随着扩散退火温度的升高，扩散系数从6.81×10〜（-8）增加到4.69×10〜（-7）cm〜2 s〜（-1），证实了Cu在较低的温度意义不大。借助阿伦尼乌斯（Arrhenius）关系式D = 3.75×10〜（-3）exp（-1.15±0.10 eV /k_ΒT）来描述Cu扩散系数的温度依赖性，并且发现MgB_2系统中相应的铜活化能为约为1.15 eV。还讨论了由于铜扩散而导致观察到的样品的微结构和超导性能改善的可能原因。

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  • 来源
    《Journal of materials science》 |2012年第11期|1965-1970|共6页
  • 作者

    M. Dogruer; G. Yildirim; E. Yucel; C. Terzioglu;

  • 作者单位

    Department of Physics, Abant Izzet Baysal University, 14280 Bolu, Turkey;

    Department of Physics, Abant Izzet Baysal University, 14280 Bolu, Turkey;

    Department of Physics, Mustafa Kemal University, 31034 Hatay, Turkey;

    Department of Physics, Abant Izzet Baysal University, 14280 Bolu, Turkey;

  • 收录信息 美国《科学引文索引》(SCI);美国《工程索引》(EI);美国《生物学医学文摘》(MEDLINE);
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