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

Fe sheath MgB2 tapes sintered at 650, 750, 850 and 950DGC, 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 950DGC completely lost the capacity of carrying superconducting current over the temperature range from 4 to 30 K. Compared to a tape sintered at 650DGC, an improvement in the infield critical current density Jc and irreversibility field *m0H*(T) was observed in a tape sintered at 750DGC. At 20 K, the Jc value was #~ 1.32 x 105 A/cm2 in self-field and the *m0H* value 4.2 T for the tape sintered at 750DGC, whereas the Jc in self-field and *m0H* values were #~ 5.9 x 104 A/cm2 and 2.8 T for that sintered at 650DGC.