Experimental Design and Investigation of Novel Pulsed Laser Deposited Structures for YBCO Based Coated Conductors
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Experimental Design and Investigation of Novel Pulsed Laser Deposited Structures for YBCO Based Coated Conductors Francesco Rizzo1, Antonella Mancini1, Angelo Vannozzi1, Andrea Augieri1, Achille Angrisani Armenio1, Fabio Fabbri1, Valentina Galluzzi1, Alessandro Rufoloni1 and Giuseppe Celentano1 1 Superconductivity Laboratory, Fusion Technical Unit – ENEA Frascati Research Centre, Via E. Fermi 45, Frascati, 00044, Italy ABSTRACT 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 MgOhomoepitaxial/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. INTRODUCTION In the last decade the visionary idea of developing cables for energy grid applications based on high temperature superconductors (HTS) instead of standard copper conductors has become more and more feasible and promising. The increasing interest in such technological implementation of high temperature superconductivity has brought the industrial world to the realization of HTS based applications [1]. However some relevant topics should yet be faced in order to ensure a widespread diffusion of coated conductors applications [2]. In particular both the realization costs and the large scale production reliability with a high quality conductor are considerable issues to deal with. In this perspective, while MgO is extensively used in the IBAD derived coated conductors [3], as far as RABITS approach is concerned, few efforts were spent so far. However, more recently the use of a MgO film as buffer layer for YBa2Cu3O7-x coated conductors has renewed a great interest because possible reductions in coated conductor processing cost are expected [4], [5], [6], [7]. In fact, MgO has a simple rock-salt structure showing a high temperature stability with a melting point of ~ 2800 °C, and it is grown on metallic films through low cost evaporation processes at relatively low temperature. In addition, it is we
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