Abstract
Ti-sheathed monocore MgB
2 wires with improved magnetic critical current density (
J
c) have been fabricated by
in situ powder-in-tube (PIT) method and characterized by magnetization, X-ray diffraction, scanning electron microscopy and electrical resistivity measurements. For the best wire, the magnetic
J
c values at 5
K and fields of 2
T, 5
T, and 8
T are 4.1
×
10
5
A/cm
2, 7.8
×
10
4
A/cm
2, and 1.4
×
10
4
A/cm
2, respectively. At 20
K and fields of 0.5
T and 3
T, the
J
c values are about 3.6
×
10
5
A/cm
2 and 3.1
×
10
4
A/cm
2, respectively, which are much higher than those of the Fe-sheathed mono-core MgB
2 wires fabricated with the same
in situ PIT process and under the same fabricating conditions. It appears that the overall
J
c for the average Ti-sheathed wires is comparable to that of the Fe-sheathed wires. Our X-ray diffraction and scanning electron microscopy analysis indicates that
J
c in the Ti-sheathed MgB
2 wires can be strongly suppressed by MgO impurities and micro-cracks.