We present a detailed study carried out on oxide buffer layers grown by Metal-Organic Decomposition (MOD) on metallic substrates for YBa2Cu3O7-x (YBCO) coated conductor applications. Precursor solutions have been made starting from acetates or pentanedionates and characterized by means of Differential Scanning Calorimetry (DSC) and Thermogravimetric (TG) analyses coupled with Fourier Transform Infra-Red spectroscopy (FT-IR). Thin buffer layers have been grown by spin-coating on Ni-5at.%W substrates. X-ray diffraction spectra (XRD), Scanning Electron Microscopy (SEM), Atomic Force Microscopy (AFM) have been employed in order to optimize buffer layers in terms of film microstructure and surface quality, with the final aims of producing a suitable template for YBCO growth. It will be shown that the optimization of the recrystallization process can lead to high quality buffer layer allowing the growth of YBCO films showing good superconductive properties.

Chemical solution deposition techniques are a very competitive low cost method to achieve coated conductors. Recently, fluorine-free CSD methods have made a great progress for the preparation of YBCO thin films and became a sustainable alternative for the well-known trifluoroacetate CSD approach. By elucidating the reaction mechanism behind this new approach, finally giving an answer to the question why it is possible to fabricate YBCO films without TFA, different processing routes were discovered giving rise to high superconducting YBCO films (>1MA.cm-2). Each route has it's own benefits. One specific route offers the opportunity to tune the crystallographic orientation. By changing one process parameter, a shift from complete c-axis to complete a-axis orientation is observed. This can be very useful for e.g. Josephson Junctions.

We particularly investigated the fundamental reaction mechanism of each reaction route, with the focus on the corresponding barium compound. Although good superconducting properties are obtained, still one major drawback limits industrial implementation: thickness. It is observed that a critical thickness of ∼500 nm eliminates the superconducting properties. Therefore, this paper gives a summary of all progress made regarding to fluorine-free water-based CSD YBCO thin films with emphasis on the possibility to control the crystallization rate.

The study of high quality YBa2Cu3O7-x (YBCO) based superconducting films is a fundamental issue to be addressed when dealing with the realization of efficient coated conductors with large current carrying capacity. In this perspective the investigation of innovative buffer layers structures able to allow epitaxial YBCO film grow on metallic substrates and to prevent contamination and degradation issues holds a central role.

In this work we thoroughly study the properties of YBCO films grown by means of pulsed lasers deposition on CeO2 template on both bare MgO single crystal and MgO-homoepitaxial/MgO single crystal substrates. Due to its high chemical and temperature stability the MgO reduces the oxygen diffusion effects. On the other hand, the CeO2 layer, pulsed laser deposited, prevents the YBCO film from metallic contamination and facilitates its epitaxial growth. Morphology and crystalline structure of buffer layers and superconductors film are investigated by using scanning electron microscopy (SEM), X-ray and electrons back-scattered diffraction techniques (XRD and EBSD).

YBCO films show good critical temperature values (Tc > 87K) with sharp transitions. These encouraging results make our structures promising candidates in the realization of high quality YBCO based coated conductors.