The effect of inhomogeneous phase on the critical temperature of smart meta-superconductor MgB2

The critical temperature (TC) 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 TC of smart meta-superconductor MgB2 was investigated. Results showed that the onset temperature (Ton C) of doping samples was lower than those of pure MgB2. However, the offset temperature (Toff C) 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 TC of sample was also studied. Results indicated that with the increase of current, Ton C is slightly increased in the samples doping with different inhomogeneous phases. When increasing current, the Toff C of the samples doped with nonluminous inhomogeneous phases was decreased. However, the Toff C of the luminescent inhomogeneous phase doping samples increased and then decreased as increasing current.