Tailoring superconductivity in Magnesium Diboride nanowires for prospective intercalation of single-layered graphene within its interstitial layers
Calderon Flores, Jean Emil
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Nanoscale superconducting materials such as MgB 2 possess a high surface-to-volume ratio yielding encouragingly high critical current densities. The strong electron-phonon coupling within MgB 2 and the connectivity between its grains give rise to a large superconducting effect under applied magnetic field. Since, MgB 2 becomes superconducting at 39 K, which is the highest known critical transition temperature ( T c ) of any non-oxide superconductor, and given that the electronic structure of MgB 2 comprises more than one superconducting energy band, there has been an intensive rush to synthesize and further examine the electronic properties of this material. Not surprisingly for a new material system, considerable controversy still prevails regarding the intrinsic properties of MgB 2 given the conflicting results obtained by different groups. In an attempt to synthesize MgB 2 nanostructures, we observe the strong tendency for MgB 2 nanostructures to get oxidized under ambient conditions. Herein, we report the synthesis of oxidized MgB 2 nanowires by coupling sol-gel synthesis with high-temperature pyrolysis. The nanowires were characterized by means of high-resolution scanning electron microscopy (HR-SEM), high-resolution transmission electron microscopy (HR-TEM), energy-dispersive X-ray spectroscopy (EDX), and X-ray diffraction (XRD). The key towards the formation of highly pure MgB 2 nanostructures involves the total exclusion of oxygen during synthesis to preclude surface oxidation of the nanostructures. Unfortunately, we have not yet been able to totally eliminate the deleterious presence of oxygen in our reactions in order to prevent the formation of oxidized MgB 2 compounds. Additional attempts have been made to synthesize single layers of graphene for possible intercalation into layers of MgB 2 with no success.