The Effect of Inhomogeneous Phase on the Critical Temperature of Smart Meta-superconductor MgB₂

The critical temperature (T_C) of MgB₂, one of the key factors limiting its application, is highly desired to be improved. On the basis of the meta-material structure, we prepared a smart meta-superconductor structure consisting of MgB₂ micro-particles and inhomogeneous phases by an ex situ process. The effect of inhomogeneous phase on the T_C of smart meta-superconductor MgB₂ was investigated. Results showed that the onset temperature (TCon) of doping samples was lower than those of pure MgB₂. However, the offset temperature (TCoff) of the sample doped with Y₂O₃:Eu³⁺ nanosheets with a thickness of 2 ∼ 3 nm which is much less than the coherence length of MgB₂ is 1.2 K higher than that of pure MgB₂. The effect of the applied electric field on the T_C of the sample was also studied. Results indicated that with the increase of current, TCon is slightly increased in the samples doping with different inhomogeneous phases. With increasing current, the TCoff of the samples doped with nonluminous inhomogeneous phases was decreased. However, the TCoff of the luminescent inhomogeneous phase doping samples increased and then decreased with increasing current.