Power-law relationship between critical current density, microstructure, and the n-value in MgB2 superconductor wires

Dissipation-free MgB2 superconducting wires are valuable in terms of practical applications. Herein, we have found a strong correlation between critical current density (J c ) and the n-value extracted from the electric field versus current density characteristic. The power-law relationship (m) between the J c and the n-value, n∝Jmc , represents a critical index which is strongly dependent on operating temperatures.