The effect of impurity addition to the critical current density of internal Mg diffusion processed MgB2 wires
葉 術軍, 戸叶 一正, 松本 明善, 熊倉 浩明 （NIMS）
Abstract:Density of the active phase in the superconducting wires is an important factor determining the current carrying properties. For the case of MgB2, the internal Mg diffusion (IMD) process can provide superconducting wires with higher density compared to the traditional powder in tube (PIT) method. This make the IMD process an attractive one for the fabrication of superconducting MgB2 wires with higher critical current densities (Jc). Some earlier studies on the PIT processed MgB2 wires show that carbon additives can enhance the Jc, where the carbon atoms partially substitute the boron in MgB2 lattice. We have recently shown that SiC and some liquid aromatic hydrocarbon (toluene, dimethylbenzene and so on) co-addition can enhance the Jc of mono core MgB2 wires. In the present contribution, we discuss the Jc of the IMD processed mono core MgB2 wires under different conditions, viz. with pure B powder, B powder with additive like SiC or toluene, B powder with SiC+toluene co-addition. Comparing the results from these samples, it is seen that the SiC+toluene co-addition gives the best Jc value. The Jc value in this case is about 50 kA/cm2 at 4.2 K under 10 T field. The compositional and micro-structural studies of the above samples are taken up to understand the mechanisms of the Jc enhancements.