Enhancement of Critical Current Density and Flux Pinning in Acetone and La₂O₃ Codoped MgB₂ Tapes

MgB₂ tape samples with simultaneous additions of acetone and La₂O₃ were prepared by an in-situ processed powder-in-tube method. Compared to the pure and single doped tapes, both transport J_c and fluxing pinning are greatly improved by acetone and La₂O₃ codoping. Acetone supplies carbon into the MgB₂ crystal lattice and increases the upper critical field, while the La₂O₃ reacts with B to form LaB₆ nanoparticles as effective flux pining centers. The improvement of the superconducting properties in codoped tapes can be attributed to the combined effects of improvement in H_c2 and flux pinning.