Effect of graphene oxide doping on superconducting properties of bulk MgB 2 (original) (raw)
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Scripta Materialia, 2012
The effects of graphene (G) and nanosilicon carbide (SiC) co-doping on the superconducting properties of MgB 2 were studied using bulk samples. SiC remains one of the best dopants which can significantly improve the high field performance, while graphene is emerging as a new dopant for MgB 2 , which can improve the zero field critical current density (J c). The superconducting properties characterized by J c , the intergrain connectivity, and the critical fields were significantly improved by the use of both SiC and graphene as dopants.
On the roles of graphene oxide doping for enhanced supercurrent in MgB2 based superconductors
Nanoscale, 2014
Due to their graphene-like properties after oxygen reduction, incorporation of graphene oxide (GO) sheets into correlated-electron materials offers a new pathway for tailoring their properties. Fabricating GO nanocomposites with polycrystalline MgB 2 superconductors leads to an order of magnitude enhancement of the supercurrent at 5 K/8 T and 20 K/4 T. Herein, we introduce a novel experimental approach to overcome the formidable challenge of performing quantitative microscopy and microanalysis of such composites, so as to unveil how GO doping influences the structure and hence the material properties. Atom probe microscopy and electron microscopy were used to directly image the GO within the MgB 2 , and we combined these data with computational simulations to derive the property-enhancing mechanisms. Our results reveal synergetic effects of GO, namely, via localized atomic (carbon and oxygen) doping as well as texturing of the crystals, which provide both inter-and intra-granular flux pinning. This study opens up new insights into how low-dimensional nanostructures can be integrated into composites to modify the overall properties, using a methodology amenable to a wide range of applications.
On the Roles of Graphene Oxide Doping for Enhanced Supercurrent in MgB 2
2006
Due to its graphene-like properties after oxygen reduction, incorporating graphene oxide (GO) sheets into correlated-electron materials offer a new pathway for tailoring their properties. Fabricating GO nanocomposites with polycrystalline MgB 2 superconductor leads to an order of magnitude enhancement of the supercurrent at 5 Kelvin /8 Tesla and 20 Kelvin /4 Tesla. Herein, we introduce a novel experimental approach to overcome the formidable challenge of performing quantitative microscopy and microanalysis of such composites, so as to unveil how GO doping influences the structure and hence the material properties. Atom probe microscopy and electron microscopy were used to directly image the GO within the MgB 2 , and we combined these data with computational simulations to derive the propertyenhancing mechanisms. Our results reveal synergetic effects of GO, namely, via localized atomic (carbon and oxygen) doping as well as texturing of the crystals, which provide both inter- and intr...
Effect of carbon-doping in bulk superconducting MgB2 samples
Physica C: Superconductivity, 2001
Bulk superconducting samples of MgB 2 were prepared by solid state reaction of stoichiometric quantities of Mg turnings and B in a sealed Ta cylinder at 890 ºC for 2 hours. The "as-synthesized" MgB 2 samples had a T c of 39 K, as defined as the onset of diamagnetism. The crystal symmetry was found to be hexagonal with lattice parameters, a=3.0856 Å, and c=3.5199 Å, similar to the literature values. To study the effect of carbon doping in MgB 2 , various C-containing samples of x varying from 0 to 1.00 in MgB 2-x C x were prepared. Magnetic characterizations indicate that the T c onset is same for pure and C-doped samples for x = 0.05, and 0.10. However, the shielding signal decreased monotonically with C content, apparently due to the presence of carbon on the grain boundaries that isolates grains and prevents flow of supercurrents on the perimeter.
Superconductor Science and Technology, 2010
Carbon (C) and rare earth oxide (REO) co-doped bulk polycrystalline MgB 2 samples with nominal compositions Mg 1−y (REO) y (B 0.95 C 0.05) 2 (where y = 0.00, 0.01, 0.03, 0.05 and REO = Eu 2 O 3 or Pr 6 O 11) have been synthesized via a solid state reaction route. The XRD results reveal the presence of impurity phases EuB 6 in Eu 2 O 3 and PrB 4 and PrB 6 in Pr 6 O 11 co-doped samples along with the main hexagonal phase of MgB 2 and a small amount of MgO. The values of upper critical field (H c2) and irreversibility field (H irr), except H c2 of y = 0.05 for Eu 2 O 3 , have been found to increase at all temperatures (<T c) with increasing doping concentration of REO. Improvements in the values of critical current density (J c) at 10 K for y = 0.01 of Eu 2 O 3 and y = 0.01, 0.03 of Pr 6 O 11 co-doped samples have been observed in high fields (>6.5 T) region. At 20 K enhancement in the high field (>6 T) J c values for y = 0.01, 0.03 of Eu 2 O 3 and y = 0.01 of Pr 6 O 11 co-doped samples are also reported in the present work. The correlations between the structural characteristics and the observed superconducting properties of the co-doped samples are described and discussed in this paper.
The effect of citric and oxalic acid doping on the superconducting properties of MgB2
Superconductor Science and Technology, 2009
In this paper we report the effect of carbon doping on the structural and superconducting properties of MgB 2 using citric and oxalic acids as carbon sources. The bulk polycrystalline samples have been synthesized via a standard solid state reaction route with composition MgB 2 + x wt% of citric and oxalic acids (x = 0, 5 and 10). The x-ray diffraction results reveal the formation of dominantly MgB 2 with only a small amount of impurity phase MgO and substitution of C at the B site of MgB 2 for both dopants. Improvements in the upper critical field (H C2), irreversibility field (H irr) and high field (>2.5 T) critical current density (J C) have been observed on C doping in the samples. The correlations between superconducting properties and structural characteristics of the samples are described and discussed in this paper.
IEEE Transactions on Applied Superconductivity, 2013
As a promising topological superconductor, Fe(Se 0.5 Te 0.5) recently attracts interest from researchers, while Bi 2 Se 3 has been considered one of the most important topological insulator materials. Therefore the Bi 2 Se 3 /FeSe 0.5 Te 0.5 bulk composite could be interesting in demonstrating novel topological properties. We investigated crystalline, morphological, magnetic, and transport properties of Bi 2 Se 3 /FeSe 0.5 Te 0.5 composite samples synthesized by the solid-state reaction method, and found that the elevated sintering temperature at the second step during the synthesis improves the crystallinity. All samples exhibit both superconductivity and ferromagnetism. Several indices of superconductivity, such as the transition temperature, change with increasing sintering temperature.