Effect of Carbon Substitution on the Superconducting Properties of Nanocarbona, Nanodiamonda and NanoaSiCaDoped 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: 01.04.2011
• Subjects: Borides; Carbon; Ceramics; Magnesium compounds; Nanocomposites; Nanomaterials; Nanostructure; Superconductivity
• 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 degree 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.