Preparation Of YBiO₃ Buffer Layers And YBCO Superconducting Thin Films By Magnetron Sputtering

YBa₂Cu₃O_x (YBCO) superconducting thin films which have widely application prospect are now attracting much attention in recent years due to the high critical current density and high critical magnetic field. Now coated superconductors normally have three layers: substrate, buffer layer and superconducting thin film. A buffer layer is necessary to prevent ion diffusion and provide a template for the subsequent growth of the YBCO superconducting layer. In this thesis, we focus on the deposition of YBiO₃ and YBCO films by magnetron sputtering method and devote to promote the practical course of the coated superconductor.First, the discovery and development course of superconducting materials as well as the preparation and characterization methods have been introduced.Second, the preparation of YBiO₃ ceramic target was studied. Based on a series of experiments, the relative density reached 91.53% prepared by cold isostatic pressing, high temperature sintering and low temperature tempering. This target was used to prepare YBiO₃ buffer films, which had smooth surface and good epitaxy.Third, the YBCO target was prepared by solid state reaction method. The deposition on LAO and Si was studied, the result indicates that when the deposition condition is the T_s=800℃, Ar:O2=30:5 and gas partial pressures=10-20Pa, DC power=96 W, we can get the most excellent films.