Effect of Carbon Substitution on the Superconducting Properties of Nanocarbon-, Nanodiamond- and Nano-SiC-Doped MgB2

• Published in: Journal of the American Ceramic Society Vol. 94; no. 4; pp. 1133 - 1137
• Main Authors: Varghese, Neson, Vinod, Krishnankutty, Rahul, Sugathan, Anees, Pazhedath, Devadas, Kavazhikathu Mohandas, Thomas, Syju, Sundaresan, Athinarayanan, Barman Roy, Sindhunil, Syamaprasad, Upendran
• Format: Journal Article
• Language: English
• Published: Malden, USA Blackwell Publishing Inc 01.04.2011
• Subjects: Borides; Doping; Magnesium compounds; Nanocomposites; Nanomaterials; Nanostructure; Phases; Shrinkage
• ISSN: 0002-7820; 1551-2916
• DOI: 10.1111/j.1551-2916.2010.04163.x

A comparative study on the effect of doping of nanocarbon (C), nanodiamond, and the well‐established nano‐SiC in MgB2 is carried out under identical doping levels (C: 2.6 and 5.2 wt%) and processing conditions (800°C, 2 h). The bulk samples are prepared via powder‐in‐sealed‐tube method. The XRD analysis shows no reacted or unreacted phases in the case of lightly nano‐C‐doped sample while all other doped samples show unreacted or/and reacted phases. The a‐axis shrinkage is observed for all doped samples, among which nano‐C‐doped samples show maximum shrinkage, an evidence for C substitution at B sites. The C substitution is also confirmed by the analysis of full‐width at half‐maximum values for (100), (101), (002), and (110) peaks which are broadened. The C substitution together with the presence of nonsuperconducting phases decreases the TC to a small extent. The JC(H) is significantly enhanced for all doped samples compared with the pure sample among which MgB1.9C0.1 (nano‐C) exhibits the best performance in JC enhancement up to a field of 8 T.