Superconducting properties of the powder-in-tube Cu-Mg-B and Ag-Mg-B wires

Abstract

The new class of Mg-B superconducting conductors was prepared using the standard in-situ powder-in-tube, PIT, method where Mg+2B mixture was used to fill the copper and silver tubes. Study of the intergranular current, grain connectivity and superconducting phases in wires were conducted by AC susceptibility measurements and direct four point transport measurements. Using SQUID magnetometer, magnetisation versus magnetic field (M-H) curves of the round wires after reactive diffusion were measured at temperatures 5K and magnetic field up to 5T to define the Jcmag . The direct current density measurements of the in-situ Cu-MgB2 performed at 4.2K gave the value of 10^9 Am-2 .