Effect of sintering temperature on structural defects and superconducting properties in MgB_2 + C_4H_6O_5

摘要

We report a systematic study on the effect of sintering temperature on the lattice parameters, amount of carbon (C) substitution, microstructure, critical temperature (T _c), critical current density (J_c), upper critical field (H_(c2)) and irreversibility field (H_(irr)) of 10 wt% Malic acid (C_4H_6O_5) doped MgB_2 superconductors. All the samples were heat treated at temperatures ranging from 600 to 900 °C. With increasing the sintering temperature both the a-axis lattice parameter and T_c are decreased compared to un-doped samples, indicating that the C released from C_4H_6O_5 substituted into Boron (B) position resulting in the enhancement of J_c, H_(c2) and H_(irr).