Rapid Pyrolysis of YBa₂Cu₃O_7-δ Films by Fluorine-Free Polymer-Assisted Chemical Solution Deposition Approach

A rapid pyrolysis heat treatment was proposed to prepare YBa₂Cu₃O_7-δ (YBCO) films by a self-developed fluorine-free polymer-assisted chemical solution deposition (PA-CSD) approach. Metal acetates and polyvinyl butyral (PVB) in YBCO wet films were pyrolyzed within 30 min, which is less than one-twentieth the pyrolysis time for conventional fluorine–free CSD methods. The influence of the rapid decomposition on the microstructures of YBCO precursor films was investigated compared to conventionally pyrolyzed films. Based on the rapidly pyrolyzed films, high-temperature firing process was further optimized to fabricate epitaxially grown YBCO films. The results demonstrate that most of the defects generated in the rapid pyrolysis process can nearly be eliminated by extending firing time to 2 h, and thus the textured YBCO films with denser and smoother morphologies were obtained with superconducting transition temperature T_c of 93.3 K and critical current density J_c of 3.1 MA/cm² at 77 K and self-field. This is almost three times of the J_c of the conventionally pyrolyzed film.