J_c anisotropy and pinning behaviors of the in-situ MgB ₂ wires with/without SiC addition

In an attempt to understand the effects of SiC addition on the pinning behavior for the in-situ PIT MgB₂ tape wire, field and temperature dependencies on critical current density, J_c and the pinning force were studied by considering applied magnetic field direction for the rectangular-shaped wire. As a result, it was clarified that the SiC-doped wire has the equiaxial pinning center and the un-doped wire has the inequi-axial pining center. Taking the pinning scaling law into account, it is found that the SiC-doped MgB₂ wire has two kinds of the pinning center and the dominant pinning center changes with temperature, that is, the pinning centers are the grain boundary and the precipitates at high and low temperatures, respectively. The un-doped MgB₂ wire is assumed to have anisotropy of the pinning mechanism.