Superconductivity of the bulk MgB₂+nano(n)-SiC composite system: a high field magnetization study

Abstract

We study the effect of nano(n)-SiC addition on the crystal structure, critical temperature (T(c)), critical current density (J(c)) and flux pinning in MgB(2) superconductors. X-ray diffraction patterns show that all the samples have MgB(2) as the main phase with a very small amount of MgO; further, with n-SiC addition the presence of Mg(2)Si is also noted and confirmed by scanning electron microscopy (SEM) and energy-dispersive spectroscopy (EDS). The T(c) value for pure MgB(2) is 18.9 K under 8 T applied field, while it is 20.8 K for the 10 wt% n-SiC doped sample under the same field. This points towards the increment in the upper critical field value with n-SiC addition. The irreversibility field (H(irr)) for the 5% n-SiC added sample reached 11.3, 10 and 5.8 T, compared to 7.5, 6.5, and 4.2 T for the pure MgB(2) at 5, 10 and 20 K, respectively. The critical current density (J(c)) for the 5 wt% n-SiC added sample is increased by a factor of 35 at 10 K and 6.5 T field and by a factor 20 at 20 K and 4.2 T field. These results are understood on the basis of superconducting condensate (sigma band) disorder and ensuing intrinsic pining due to B-site C substitution clubbed with further external pinning due to available n-SiC/Mg(2)Si pins in the composite system.

Enhanced critical parameters of nanocarbon doped MgB2 superconductor

“…Thus, it enhances the critical parameters both ways and results in superior results than through other dopants. [13][14][15] Substantial increment is noticed in the H c2 ͑0͒ value for the nanocarbon doped samples as compared to pristine MgB 2 on applying suitable theoretical model. The quantitative description is given in Sec.…”

“…[13][14][15] Thus, along with MgB 2 , the nanocarbon doped samples are also taken into consideration. The critical parameters such as H c2 , H irr , and J c enhance significantly by nanocarbon substitution at boron site.…”

Synthesis and characterization of excess magnesium MgB2 superconductor under inert carbon environment

“…Any attempts to increase the superconducting transition temperature [6][7][8][9] have not achieved success yet [10][11][12], due to its typical phonon coupling mechanism [13][14][15][16][17][18]. But the other critical parameters like critical current density, and upper critical field can be enhanced remarkably by nano-particle doping [19][20][21][22][23][24][25][26]. Moreover, the mechanical properties of MgB 2 superconductor also vary depending upon the dopant as well as on the synthesis route.…”

Effect of rare-earth doping on the superconducting properties of MgB2

“…These impurity phases can enhance the electron scattering, and hence the decreased RRR value. 15 The insets of Fig. 2͑a͒ and 2͑b͒ show, respectively, the R-T plots of Pr 6 O 11 and Eu 2 O 3 -doped samples ͑x = 0.01͒ measured at different fields ͑0-8 T͒.…”