Aging of Precursor Solutions Used for YBCO Films Chemical Solution Deposition: Study of Mechanisms and Effects on Film Properties

The proposed study investigates the aging of two precursor solutions used for the chemical solution deposition of YBa
₂
Cu
₃
O
_7-x
(YBCO) and composite YBCO films with nanostructured inclusions of BaZrO
₃
(YBCO-BZO). The stability of precursor solutions plays a crucial role in determining the crystalline quality and the superconducting properties of YBCO films. Although low-or free-fluorine solutions are promising in order to improve the synthesis route and to reduce the environmental impact, the poor stability of the solution is the major drawback of the low-fluorine precursors since they degrade faster (4-6 weeks) than other precursor solutions for superconducting layers (e.g., trifluoroacetates solutions are stable up to 6 months) or buffer layers (stable for several months). Therefore, a deeper comprehension of the degradation mechanisms is fundamental to properly optimize the composition of the precursor solution. The current work studies two precursor solutions (for YBCO and YBCO-BZO) that are complex systems, in which different interactions need to be considered: most of all, the nature of ligands (acetate, propionate, ammonia) that complex each metal and influence not only the solution stability but also the quality of the deposited film. Thus, information obtained from different analyses is correlated with morphological, structural, and superconducting properties of the deposited film in order to understand the underlying chemical mechanisms of aging (salts precipitation, oxidation, polymerization) and its effects.