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 MgB
₂
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 MgB
₂
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 MgB
₂
samples were decreased by different degrees, which indicates a gradual substitution of Carbon for the Boron sites in the MgB
₂
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 MgB
₂
sample with 20% PZA doping and sintered at 800°C for 1 h reached 0.8 × 10
⁴
A/cm
²
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 MgB
₂
grains.