Effect of combined addition of graphene oxide and citric acid on superconducting properties of MgB₂Effect of combined addition of graphene oxide and citric acid on superconducting properties of MgB₂
In the present work, polycrystalline samples with compositions MgB₂ + 3wt% GO + x wt% C₆H₈O₇ (x = 0, 5 and 10) have been synthesized to study the effect of combined addition of graphene oxide (GO) and citric acid (C₆H₈O₇) on superconducting properties of MgB₂. X-ray diffraction studies show the formation of hexagonal crystal structure of MgB₂ with space group P6/mmm in all synthesized samples. We observe that the addition of GO in the sample improves the grain connectivity and consequently enhances the critical current density significantly with no substantial change in Tc. However for this sample, there is no significant improvement in Hc2 and Hirr. With the combined addition of GO and citric acid, the JC(H), Hc2 and Hirr are observed to improve substantially as compared to the pristine MgB₂ and GO added MgB₂ samples. For example JC(10 K, 5 T) of sample x = 10 has improved by a factor of ∼15 as compared to pure MgB₂ sample and by a factor of ∼5.5 as compared to the x = 0 sample. Furthermore, Hc2(0) for x = 10 sample has enhanced by 13 T as compared to pure MgB₂ while it has increased by ∼10 T in comparison to x = 0 sample. Enhanced flux pinning has been observed with the combined addition of GO and citric acid
