Properties of MgB₂ wires doped with BaZrO₃ nanopowder made by a modified internal magnesium diffusion process

We report an investigation of MgB₂ wires doped with BaZrO₃ nanoparticles produced by a modified internal magnesium diffusion (MIMD) process. The structure of the Nb-sheathed MgB₂ cores, transition temperature ( T _c), critical current density ( J _c) and pinning behaviour were studied and compared. Because the MgB₂ cores made by MIMD process are extractable, the grain connectivity and the phase composition of the cores were also analysed. The wires exhibited very good phase purity and sharp transitions with high critical temperature (close to 38 K); the best sample of the wires under study showed enhanced J _c with almost 2 MA cm⁻² at 4.2 K and 2 T. These results demonstrate the high quality of MgB₂ doped with BaZrO₃ nanopowder made by the MIMD method. (paper)