Study On Optimization Of The Metal Substrate Surface Roughness By Solution Deposition Planarization Technology

Due to its high irreversible field, excellent current carrying capacity, and lowmicrowave resistance，the YBa2Cu3O7-x（YBCO） high temperature superconductingtapes are widely used in both electric power field and low current field. Generally, thebuffer layer is needed to provide the seed layer for epitaxial growth of YBCO film andblock the interdiffusion between YBCO and the metallic substrate. The ion beamassisted deposition （IBAD） and the inclined substrate deposition （ISD） are the mostpopular techniques to prepare textured buffer layer on amorphous flexible metallicsubstrate. However, the surface of flexible metallic substrates is usually not flat enough,so polishing treatment is needed. Compared with the traditional polishing process,solution deposition planarization （SDP） method has many advantages such as low cost,simple equipment, convenient process, high utilization rate and long length accessibility,which make it suitable for industrial production. Since the surface roughness of thebuffer layer could be increased by the uncontrollable crystal growth of the crystallinefilms, in this paper, we focus on the fabrication of amorphous films on the Hastelloysubstrate by SDP method.According to reports in the literature, three different precursor solutions werechosen: yttrium oxide precursor solution, Yttria and Alumina （YALO） precursorsolution and silica precursor solution. Detailed inverstigation on the stability ofprecursor solution were carried out. The influences of precursor concentration, heattreatment temperature and the number of coating layers on surface roughness,morphology, crystallization and the thickness of the film are systematically studied. Byoptimizing the process parameters, the smooth and crack free amorphous thin filmswhich meet ion beam assisted deposition and inclined substrate deposition technologystandard were achieved. And the roughness （RMS） of the optimal amorphous films areas follows:1.075nm（Y₂O₃）,1.243nm（YAlO）and1.417nm（SiO₂）.The influence of the SDP prepared buffer layer on the property of YBCO coatedconductors was addressed，the critical current density of YBCO film on LAO singlecrystal substrate was improved from2.2to2.4MA/cm²by the insertion of amorphous Y₂O₃film. The ion beam assisted deposition MgO films based on YAlO amorphous thinfilms present pure c axis orientation. Meanwhile, c-axis oriented MgO layer was alsosuccessfully fabricated by inclined substrate deposition on Y₂O₃and SiO₂amorphouslayer.