Solution design for low-fluorine trifluoroacetate route to YBa2Cu3O7 films

Abstract

We present our work in the preparation of metallorganic precursor solutions with reduced fluorine content, able to fulfil the requirements for high-performance superconducting YBCO epitaxial layers as a promising approach to low cost and scalable coated conductors. Six different solutions using different quantities of fluorine and non-fluorine carboxylate precursors with a total amount of fluorine from 10 to 50% that of standard trifluoroacetic acid (TFA) solutions. For stabilization purposes different coordinating agents have been used and the solution rheology has been modified for proper substrate wettability. Thermal decomposition analysis and infrared spectroscopy performed directly in films, have revealed that the decomposition takes place in two consecutive stages around 265 and 310 °C respectively, and nuclear magnetic resonance (NMR) analysis could unveil the chemical reactions taking place in the solution. Using the solutions with 20% fluorine and upon optimization of the growth process parameters, YBCO layers with T c and J c(77 K) of 90 K and 4 MA cm−2 are obtainedThe authors acknowledge the financial support from MICINN (Consolider NANOSELECT, CSD2007-00041, MAT 2011-28874-C02, MAT2014-51778-C2-2-R); Generalitat de Catalunya (Pla de Recerca 2014-SGR-753 and XaRMAE), and EU (FP7 NMP-LA-2012-280432 EUROTAPES project and MP1201 Cost action