Enhanced superconducting properties of MgB₂ tapes achieved by treating B powder with glycolic acid

MgB₂ tapes were fabricated by the in situ powder-in-tube method using C₂H₄O₃-treated B powder as a source material. It is found that the J_c values of MgB₂ tapes are significantly improved by treating B powder with C₂H ₄O₃. At 4.2K, the J_c of the C₂H ₄O₃-treated sample sintered at 800 °C reaches 5 × 10³Acm^-2 at 12T. The C₂H ₄O₃-treated B improves not only the upper critical field through enhancing intraband scattering but also the flux pinning by increasing grain boundaries and C substitution effects. A larger amount of intragranular structural defects and grain boundaries were found in the C₂H ₄O₃-treated MgB₂ matrix. Benefiting from the good crystallinity, the C₂H₄O₃-treated tape sintered at 800 °C shows a bigger active area fraction and a higher J _c than the sample sintered at 700 °C. These results suggest that treating B powder with C₂H₄O₃ is an effective way to enhance the critical current density of MgB₂ superconductors.