Study on the Effect of Doping With Poly Zinc Acrylate Complex (PZA) on the Superconducting Properties of Bulk ${\rm MgB}_{2}$

In this work, the effect of doping with 5% to 20% Poly Zinc Acrylate complexes (PZA) on the MgB₂ phase formation was studied. The changes of the lattice parameter and the amount of substituted Carbon, of the microstructure as well as the critical current temperature (T_c) and the critical current density (J_c) of bulk MgB₂ have been studied systematically. The DTA-TG and IR results show that the PZA was decomposed between 400??C and 600??C and the main decomposition products were carbonized polymers and ZnO. The lattice parameters ?? in all PZA doped MgB₂ samples were decreased by different degrees, which indicates a gradual substitution of Carbon for the Boron sites in the MgB₂ lattice structure. Comparing with the undoped sample, the J_c values of all the doped samples were enhanced for about an order of magnitude under high magnetic fields. The J_c value of MgB₂ sample with 20% PZA doping and sintered at 800??C for 1 h reached 0.8 ?? 10⁴ A/cm² at 5 k and 8 T. TEM images reveled a considerable amount of second phase particles of ~5 nm size and high density dislocations were observed in MgB₂ grains.