Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
8164668 | Physica C: Superconductivity and its Applications | 2014 | 6 Pages |
Abstract
We report, for the first time, an increase in the superconducting critical temperature, TC of commercial “dirty” MgB2 by a nonsubstitutional hole-doping of the MgB2 structure using minute, single-wall carbon nanotube (SWCNT) inclusions. We varied the SWCNTs concentration from 0.05Â wt% to 5Â wt% and investigated the temperature-dependent resistivity from 10Â K to 300Â K. We used micro-Raman spectroscopy, field-emission scanning electron microscopy, and X-ray diffraction to analyze the interfacial interactions between the SWCNTs and the MgB2 grains. We obtained an increase in TC from 33.0 to 37.8Â K (ÎTC+=4.8K), which is attributed to charge transfer from the MgB2 structure to the SWCNT structure. The charge transfer phenomenon is confirmed by micro-Raman analysis of the phonon states of the SWCNT tangential band frequency in the composites. We determined the charge transfer per carbon atom to be 0.0023/C, 0.0018/C and 0.0008/C for 0.05Â wt%, 0.5Â wt% and 5Â wt% SWCNT inclusions, respectively, taking into account the contributions from the softening of the lattice constant and the nonadiabatic (dynamic) effects at the Fermi level. This report provides an experimental, alternative pathway to hole-doping of MgB2 without appealing to chemical substitution.
Keywords
Related Topics
Physical Sciences and Engineering
Physics and Astronomy
Condensed Matter Physics
Authors
Danhao Ma, Ruwantha Jayasingha, Dustin T. Hess, Kofi W. Adu, Gamini U. Sumanasekera, Mauricio Terrones,