EFFECTS OF SINTERING TEMPERATURE ON SUPERCONDUCTIVITY IN Ti-SHEATHED MgB[sub 2] WIRES

The effects of sintering temperature on the superconducting properties of Ti‐sheathed MgB2 wires have been studied. The wires were fabricated by in situ powder‐in‐tube (PIT) method and characterized by x‐ray diffraction, magnetization, scanning electron microscopy and transport measurements. Samples were sintered for 30 minutes at the following temperatures: 650° C, 700° C, 750° C, 800° C, and 850° C. It is found that the cores of these wires are almost in pure MgB2 superconducting phase, indicating that the Ti‐sheath does not react with Mg or B. The superconducting transition temperature Tc decreases from 36 K to 34.2 K with the decrease of the sintering temperature from 850° C to 650° C. At 5 K and 20 K, critical current density Jc peaks up for samples sintered at 800° C, which is in sharp contrast with previously reported result that for Fe‐sheathed MgB2 wires, Jc peaks up at sintering temperature of 650° C.