Complexation behavior in aqueous edta sol-gel systems for the synthesis of YBa2Cu3O7-x high-temperature superconductors

Abstract

Two water-based YBa2Cu3O7-x precursor solutions using edta (ethylenediaminetetraacetic acid) as complexing agent are presented. These precursors were employed to deposit thin layers of high-temperature superconducting (HTSC) materials. The influence of the complexation behavior on the formation of transparent and homogeneous solutions and gels after the combination of metal acetates and other modifiers was studied, compared and interpreted using metal-ligand equilibria. The occurrence of different chemical species at different pH values appears to be related to stable gel formation conditions. It is found that both acetic acid and edta play an important role in controlling the condensation reaction to form a continuous network polymer. The precursors were used to deposit textured superconducting thin films on SrTiO3 (STO) substrates by dip coating. Analysis by X-ray diffractometry (XRD) indicated that a single YBCO (yttrium barium copper oxide) phase was obtained. Attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR) was used to determine the carbon residue level in the YBCO final materials, which was lower than 0.01%. © 2012.