Investigation Of Amorphous Oxide Thin Film Preparation Using Chemical Solution Deposition

The second generation YBa2Cu3O7-x high temperature superconductor(HTS) wires have broad application prospects in superconducting electricity transmission lines, superconducting magnetic, superconducting motor, etc. Ion-beam assisted deposition(IBAD) biaxial texture magnesium oxide route severed as a main steam approach to obtain high-performance YBCO coated conductor. However, high quality IBAD-MgO required that surface root square roughness of substrates less than 2nm on 5 μm×5 μm areas. In this paper, chemical solution deposition planarization method(SDP) was used for fabrication of amorphous oxide barrier layers on Hastelloy substrates to decrease surface root square roughness, and a full set of a roll-to-roll system was independently designed. In order to increase the critical current of HTS wires, the feasibility of fabricating multiple superconducting layers on single HTS wire was confirmed by using metal organic solution(MOD) deposited CeO2 film on YBCO surface.Amorphous Y2O3 film was deposited by SDP method on Hastelloy substrates surface. Factors which include the temperature of rapid heat treatment process, dipping speed, number of layers, affected the roughness of amorphous Y2O3 film surface and the crystallization process of amorphous Y2O3 was studied. The optimal RMS roughness of amorphous Y2O3 surface was 0.44 nm on 5 μm×5 μm areas by SDP process.Preparation of amorphous Y-Al-O film was studied, Y-Al-O film has higher crystallization temperature than Y2O3 film, and it is believed to be helpful for fabricating high quality HTS wires. The number of layers, temperature of rapid heat treatment process, dipping speed, ratio of Y and Al were studied on the influence of RMS roughness of amorphous Y-Al-O film surface. According to the result of the study, the final RMS roughness of amorphous Y-Al-O surface was 1nm on 5 μm×5 μm areas by SDP process.After solving the cracking on amorphous film edge which appearing on SDP process, 28m-length SDP amorphous oxide barrier film with RMS roughness below 2nm were prepared on Hastelloy substrates. IBAD-MgO/homo-epitaxial MgO films were deposited on these substrates with an in-plane texture of 5.15°, out-plane texture of 3.64° and subsequent YBCO deposited by MOCVD indicates the critical current densities of 2.0 MA/cm2 at 77 K.By studying the effecte of time of rapid heat treatment process to texture of Y2O3 film which deposited by MOD method on YBCO surface, the final Y2O3 film achieved an in-plane texture of 4.61° and out-plane texture of 4.38°. The effecte of heat treatment temperature on the microstructure of CeO2 films was also studied. The CeO2 film which deposited on YBCO surface by MOD mothed with an in-plane texture of 5.02° did not induce the reduction of superconducting performance after annealing under oxygen atmosphere.