Tfa-mod, The Ybco Superconducting Thin Films Preparation

Due to its lower ac loses and better in-field performance, YBa2Cu3O7-δ(YBCO) high-temperature superconductor(HTS) thin films attracted the attention of the reserchers worldwide. Metal-organic deposition using trifluoroacetates (TFA-MOD) process is attractive for its low cost, the facility of scalability and composition control among lots of methods. In this dissertation, the structure and properties of the YBCO films with TFA-MOD process were studied.The effect of most important parameters (temperature) of the TFA-MOD, on the microstructure and properties of YBCO thin films were studied,and high quality YBCO films with critical current density (Jc) of 3.8MA/cm2(77K,0T) had been grow on LaAlO3 (LAO) single crystal substrates. Studies of the TFA-MOD process on different single crystal, such as LAO, SrTiO3(STO), Ytrimumm stabilized Zirconia (YSZ) showed that the crystals,which crystal lattices were matched with YBCO could be good templates for depositing YBCO films. Films were also deposited on buffered RABiTS Ni substrates with CeO2/YSZ/CeO2, CeO2, and STO respectively. The results indicated that a too high substrate temperature and a rough surface of the CeO2 buffer will help the formation of BaCeO3 and deteriorate to epitaxial growth of the YBCO films. But on STO buffer, it is not so critical.Based on the traditional TFA-MOD, a rapid pyrolysis process TFA-MOD was developed. In this method, we added diethanolamine (DEA) in the dissolvent. DEA enables to modify copper ion chemisty in the solution and extends the range of pyrolysis temperature, so we can decrease time of the pyrolysis process from multiple hours to only 60s at 325℃in atmospheric. By this method, YBCO films with Jc of the order of 106A/cm2 (77K, 0T) on LAO single crystal were obtained, so this rapid pyrolysis process TFA-MOD is of great value to deposit YBCO film effiently.