Correlation between Jc enhancement and phase homogeneity in Sn-Ge co-doped Nb3Al superconducting wires

摘要

In response to the growing demand for critical current density (J(c)) in superconducting wires, Sn-Ge co-doped Nb3Al wires were fabricated by the rapid-heating, quenching and transformation (RHQT) method. Physical Property Measurement System-Vibrating Sample Magnetometer (PPMS-VSM) was used to perform magnetic measurements at low-temperature and external field to estimate J(c) and superconducting transition temperature (Tc). Backscattered electron (BSE) image acquisition and EDS analysis of the polished surface by FESEM were used to determine phase homogeneity and elemental distribution. A significant positive correlation was found between J(c) (up to 7 T at 8 K) and delta T-c. Compared with binary sample, doubled J(c) was obtained in the low-dose Sn-Ge co-doped Nb3Al wire, reaching 3.01 x 10(3) A/mm(2), 1.46 x 10(3) A/mm(2) and 0.39 x 10(3) A/mm(2) at 5 T and 8 K, 10 K and 12 K, respectively. The increase in J(c) can be attributed to the enhancement of the homogeneity of the superconducting phase, especially the distribution of Al element therein.