Study of the Effects of the SiC Doping on the Critical Current Density of the Ti-sheathed MgB$_{2}$ Superconducting Wires

The effects of the SiC doping on the magnetic critical current density ($J_{c})$ of the Ti-sheathed MgB$_{2}$ superconducting wires were studied for the first time. Two groups of Ti-sheathed MgB$_{2}$ wire samples were prepared and studied: for the first group, the size of the SiC particles was 20 nm and the concentrations were 5{\%}, 10{\%}, and 15{\%}; for the second group, the concentration of the SiC dopant was 10{\%} and the sizes of the SiC particles were 20 nm, 45 nm, and 100-200 nm. Contrary to the $J_{c}$ results reported on the SiC-doped Fe-sheathed MgB$_{2}$ wires, we found that the $J_{c}$ for the SiC-doped Ti-sheathed MgB$_{2}$ wires decreases with both the concentration and particle size of the SiC dopant. We found that only for the wires with 100-200 nm SiC size, the $J_{c}$ is greater than that of the undoped MgB$_{2}$ wires. This unusual dependence of $J_{c}$ on the size and concentration of the SiC dopant is discussed in association with the results from the magnetization, electrical resisitivity, x-ray diffraction and scanning electron microscopy measurements.