. (2015). Significantly enhanced critical current density in nano-MgB2 grains rapidly formed at low temperature with homogeneous carbon doping. Superconductor Science and Technology, 28 (5), 055005-1-055005-7.Significantly enhanced critical current density in nano-MgB2 grains rapidly formed at low temperature with homogeneous carbon doping AbstractHigh performance MgB 2 bulks using carbon-coated amorphous boron as a boron precursor were fabricated by Cu-activated sintering at low temperature (600 °C, below the Mg melting point). Dense nano-MgB 2 grains with a high level of homogeneous carbon doping were formed in these MgB 2 samples. This type of microstructure can provide a stronger flux pinning force, together with depressed volatility and oxidation of Mg owing to the low-temperature Cu-activated sintering, leading to a significant improvement of critical current density (J c ) in the as-prepared samples. In particular, the value of J c for the carbon-coated (Mg 1.1 B 2 )Cu 0.05 sample prepared here is even above 1 x 10 5 A cm −2 at 20 K, 2 T. The results herein suggest that the combination of low-temperature Cu-activated sintering and employment of carbon-coated amorphous boron as a precursor could be a promising technique for the industrial production of practical MgB 2 bulks or wires with excellent J c , as the carbon-coated amorphous boron powder can be produced commercially at low cost, while the addition of Cu is very convenient and inexpensive.Keywords carbon, homogeneous, nano, density, current, critical, enhanced, temperature, low, doping, formed, significantly, rapidly, grains, mgb2 Disciplines Engineering | Physical Sciences and Mathematics Publication DetailsLiu, Y., Lan, F., Ma, Z., Chen, N., Li, H., Barua, S., Patel, D., Shahriar, M., Hossain, A., Acar, S., Kim, J. & Dou, S. Xue. (2015). Significantly enhanced critical current density in nano-MgB2 grains rapidly formed at low temperature with homogeneous carbon doping. Superconductor Science and Technology, 28 (5) AbstractsHigh performance MgB 2 bulks using carbon-coated amorphous boron as boron precursor were fabricated by Cu-activated sintering at low temperature (

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To search a proper dopant to further improve superconductivity in 11 type Fe-based superconductors makes sense to both their superconductivity mechanism and possible technological applications. In present work, Mg doped FeSe polycrystalline bulks were obtained by a two-step solid-state reaction method. Even though there are many MgSe and iron impurities existing in the Mg heavy doped FeSe bulks, they exhibit obviously increased Tc compared to undoped FeSe sample. It was found that Mg addition has little effect on the crystal lattice parameters of superconducting β-FeSe, whereas leads to the formation of nano-layered grain structure consisted of MgSe and β-FeSe with similar X-ray diffraction characteristics. Lots of nano-structural interfaces between FeSe and MgSe formed in this homogenous layered grain structure have significant effect on the superconducting properties and are responsible for the enhancement of Tc, as like the case of FeSe thin film on some specific substrates. Our work not only demonstrates a powerful way for raising Tc in bulk superconductors, but also provides a well-defined platform for systematic studies of the mechanism of unconventional superconductivity by considering interface effect.

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