Lim Jun Hyung, Lee Chang Min, Park Jin Hyun, Choi Jun Hyuk, Shim Jong Hyun, Joo Jinho, Lee Young Hee, Kang Won Nam, Kim Chan-Joong
School of Advanced Materials Science and Engineering, Sungkyunkwan University, Suwon 440-746, Korea.
J Nanosci Nanotechnol. 2009 Dec;9(12):7388-92. doi: 10.1166/jnn.2009.1756.
We fabricated carbon nanotube (CNT)- and nano-carbon (NC)-doped MgB2 using an in-situ process in order to improve the critical current density (J(c)) at high magnetic field. We then evaluated the effects of the doped carbon content on phase formation, microstructure, and critical properties. CNT had a diameter and length of 5-10 nm and 0.5-1 microm, respectively, and NC was a sphere with a diameter of 5-30 nm. The bulk MgB(2-x)C(x) samples with x = 0, 0.05, and 0.1 for NC and CNT were fabricated by pressing into pellets and then sintered at 900 degrees C for 30 min. NC was more effective than CNT for carbon doping at the B site in MgB2 and, therefore, the NC-doped MgB2 samples had a lower critical temperature (T(c)) of 35.0-34.7 K than that of the CNT-doped samples (36.4-36.1 K). In addition, the J(c)(B) behavior was improved when NC and CNT were doped due to doping effect. Microstructural observation suggested that the nano-sized and unreacted NC particles and the nanodomain MgB2 acted as effective flux pinning centers for the NC- and CNT-doped MgB2, respectively.
我们采用原位工艺制备了碳纳米管（CNT）和纳米碳（NC）掺杂的MgB₂，以提高其在高磁场下的临界电流密度（J(c)）。然后，我们评估了掺杂碳含量对相形成、微观结构和临界性能的影响。CNT的直径和长度分别为5-10纳米和0.5-1微米，NC是直径为5-30纳米的球体。通过压制成丸，然后在900℃下烧结30分钟，制备了x = 0、0.05和0.1的NC和CNT的块状MgB(2-x)C(x)样品。在MgB₂的B位进行碳掺杂时，NC比CNT更有效，因此，NC掺杂的MgB₂样品的临界温度（T(c)）为35.0-34.7K，低于CNT掺杂样品（36.4-36.1K）。此外，由于掺杂效应，掺杂NC和CNT时J(c)(B)行为得到改善。微观结构观察表明，纳米尺寸且未反应的NC颗粒和纳米域MgB₂分别作为NC和CNT掺杂的MgB₂的有效磁通钉扎中心。
