  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.
