Vital variation in superconducting performances of Bi-2212 through lithium substitution

This exhaustive study discusses the notable alterations in micro-structural, electrical, and superconducting properties of Bi2Sr2CaCu2-xLixOy (x = 0, 0.05, 0.1, 0.15, and 0.20) ceramics with the partial substitution of Li for Cu. Solid state reaction method was used as the production method of the samples in terms of being simplicity, cheapness, and easy-repeatable. XRD analysis yields that Bi-2212 is the main phase with minor reflections of Bi-2201 and Bi-2223 in all samples. From SEM images, it seems that haphazardly oriented flaky grains partially are replaced by rod-like and rectangular prism-type grains that are closely packed. Magnetic field-induced broadening phenomena of the resistivity transitions are investigated by means of thermally activated flux flow (TAFF) and pinning (activation) energy (U) of the samples are found to be U(H,T)similar to Delta TH-eta. Moreover, some important parameters including critical transition temperatures (T-c(onset), T-c(mid), T-c(offset)), residual resistivity (rho(0)), irreversibility fields (H-irr), upper critical fields (H-c2), coherence length (xi), and penetration depth (lambda) are deduced from resistivity measurements under applied magnetic fields between 0 and 5T. All these parameters tend to improve with Li-content and reaches to their optimum value in x = 0.10 sample. To give some numerical results, T-c(offset) value, which is an indicator of interlayer coupling quality, increases from 67.4 to 82.1 K with Li-content for 0 T. Besides, in the presence of the magnetic field, the transition width, Delta T = T-c(onset)-T-c(offset), is 54.5 K in the undoped sample, while Li-content samples stand more robust against the magnetic field and Delta T is 47.6 K for x = 0.10 sample at 5T. Likewise, H-c2(0) values of the samples get improved from 25.73 (x = 0) to 45.49 T (x = 0.10) with Li-content. To put it briefly, invoking all experimental outcomes and theoretical approaches, it can be deduced that appropriate amount of Li-incorporation into the Bi-2212 can be useful tool for the practical applications

Automated summary

This study extensively examines the changes in microstructural, electrical, and superconducting properties of Bi2Sr2CaCu2-xLixOy ceramics with the substitution of Li for Cu. Solid state reaction method was used for sample production due to its simplicity, affordability, and reproducibility. XRD analysis showed that Bi-2212 was the main phase in all samples, with minor reflections of Bi-2201 and Bi-2223. SEM images revealed that randomly oriented flaky grains were partially replaced by rod-like and rectangular prism-type grains that were closely packed. The resistivity transitions under magnetic fields were investigated, and important parameters such as critical transition temperatures, residual resistivity, irreversibility fields, upper critical fields, coherence length, and penetration depth were deduced from the resistivity measurements. These parameters improved with increasing Li-content and reached their optimal value in the x = 0.10 sample. Overall, the appropriate incorporation of Li into Bi-2212 can be a useful tool for practical applications.