Effects of nano-carbon doping and sintering temperature on microstructure and properties of MgB2 |
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Authors: | Jun Hyung Lim Jong Hyun Shim Jun Hyuk Choi Jin Hyun Park Won Kim Jinho Joo Chan-Joong Kim |
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Institution: | aSchool of Advanced Materials Science and Engineering, Sungkyunkwan University, Suwon, Gyeonggi, Republic of Korea;bNeutron Science Division, Korea Atomic Energy Research Institute, Daejeon, Republic of Korea |
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Abstract: | We fabricated nano-carbon (NC) doped MgB2 bulks using an in situ process in order to improve the critical current density (Jc) under a high magnetic field and evaluated the correlated effects of the doped carbon content and sintering temperature on the phase formation, microstructure and critical properties. MgB2−xCx bulks with x = 0 and 0.05 were fabricated by pressing the powder into pellets and sintering at 800 °C, 900 °C, or 1000 °C for 30 min.We observed that NC was an effective dopant for MgB2 and that part of it was incorporated into the MgB2 while the other part remained (undoped), which reduced the grain size. The actual C content was estimated to be 68–90% of the nominal content. The NC doped samples exhibited lower Tc values and better Jc(B) behavior than the undoped samples. The doped sample sintered at 900 °C showed the highest Jc value due to its high doping level, small amount of second phase, and fine grains. On the other hand, the Jc was decreased at a sintering temperature of 1000 °C as a result of the formation of MgB4 phase. |
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Keywords: | Critical current density Doping effect MgB2 Nano-carbon |
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