Research On Preparation Process And Mechanism Of GdBiO₃ Buffer Layer By A CSD Based On Lactic-Acid

It is particularly critical for the research of the low-cost continuous production of coated conductors as the requirement of the industrialization for the coated conductors these years. In this thesis, the preparation process and mechanism of phase epitaxy of a CSD(chemical solution deposition) quick preparation method based on lactic-acid for the preparation of GdBiO3(GBO) buffer layer on YSZ(Yttria-stabilized zirconia) Single crystal was researched aimed at quick and low-cost preparation.In this thesis, the process of CSD quick preparation based on lactic-acid was discussed. For the concentration of colloid, according to the requirements of the film flatness and thickness, obtained at lower concentrations of situation may lead to film defects, instability while a concentration of 0.7mol/L with a stable quality is a suitable concentration. The influence of the temperature and humidity during the coating was discussed, and provided an alternative experience chart for spin coating speed in the coating process. After a detail study on the volatilization of lactic-acid, the best temperature of volatilization is between 110℃ and the boiling point lactic-acid according to the result of the experiment. During the decomposition process of two-step method the defects occurred on the film, after the analysis of the reasons of the defects, a proper control of the heating up was used during the decomposition process which resulting in a smooth dense film.The phase epitaxy of GdBiO3 film was investigated in detail on the process and mechanism and an YBCO layer with the onset temperature of 90K was obtained on the epitaxial GdBiO3 film. The change of peak intensity with time and the impact of temperature and atmosphere on phase epitaxy were investigated. The result shows that both in air and Ar appear two more suitable epitaxial ranges, which is due to the competition between the nucleation and growth as investigated. It was found that the epitaxial temperature in Ar is lower than in Ar, which was considered caused by the state of the thermodynamics and kinetics move to lower temperature while the film processes under Ar atmosphere. The intensity varies the processing time shows that lots of small grains appear in the beginning of the epitaxial process. According to the analysis above, a method based on induced nucleation at high temperature and continues to grow and recrystallization at a lower temperature which can improve the texture degree was proposed, and a route based on this method by holding at 825℃ for 2 min then with the furnace cooling to 800℃ and keep for 1h achieved an excellent texture degree.