The effects of sintering temperature on superconductivity in MgB2/Fe wires

We studied the effects of sintering temperature on the phase transformation, lattice parameters, full width at half-maximum (FWHM), strain, critical temperature (Tc), critical current density (Jc) and resistivity (p) in MgB2/Fe wires. All samples were fabricated by the in situ powder-in-tube method (PIT) and sintered within a temperature range of 650-900 deg C. It was observed that wires sintered at low temperature, 650 deg C, resulted in higher Jc up to 12 T and lower Tc. The best transport Jc value reached 4200 A cm-2 at 4.2 K and 10 T. This is related to the grain boundary pinning due to small grain size. On the other hand, wires sintered at 900 deg C had a lower Jc in comination with a higher Tc.