Study on PEG assisted TFA-MOD method for rapid fabrication of YBa2Cu3O7?? thin films: Influence of PEG additive amount in precursor solutions

Superconducting YBa₂Cu₃O_7-δ (YBCO) thin films with critical current density over 4 MA/cm2 (77 K, self field) can be routinely obtained in only 130 min thanks to the polyethylene glycol (PEG) assisted trifluoroacetate metal-organic deposition (TFA-MOD) method. In this study, the amount of PEG2000 additive in the trifluoroacetate based precursor solutions, which has previously been proved to be effective to shorten the heat treatment process, was found to influence the superconducting, mechanical and crystallographic properties of the obtained YBCO thin films in different extent. By tuning the mass fraction of PEG2000 additive (ω) in the precursor solution, it was found that the critical current density (J_c) and the critical temperature (T_c) both had the optimal values when ω was 20-30%. By in-depth analysis of the X-ray diffraction measurement results by Nelson-Riley and Willamson-Hall Methods, the c-axis length, micro-strain of the YBCO films prepared with ω ranging from 0 to 50% could be obtained. It was revealed that the c-axis length and the micro strain of the YBCO films exhibit a similar tendency to that of the critical current density and critical temperature, i. e. their values are optimized when ω was 20-30%.