Transport critical current density of Fe sheath MgB2 tapes sintered at different temperatures

Abstract Fe sheath MgB 2 tapes sintered at 650, 750, 850 and 950 °C, respectively, for 2 h in a high purity argon gas were prepared using the powder-in-tube method. Transport critical current densities of tapes were measured in the fields up to 10 T from 4 to 30 K. Both tapes sintered at 850 and 950 °C completely lost the capacity of carrying superconducting current over the temperature range from 4 to 30 K. Compared to a tape sintered at 650 °C, an improvement in the in-field critical current density J c and irreversibility field μ 0 H * ( T ) was observed in a tape sintered at 750 °C. At 20 K, the J c value was ∼1.32×10 5 A/cm 2 in self-field and the μ 0 H * value 4.2 T for the tape sintered at 750 °C, whereas the J c in self-field and μ 0 H * values were ∼5.9×10 4 A/cm 2 and 2.8 T for that sintered at 650 °C.