A novel process for the preparation of Bi2Sr2CaCu2O8+ films with smooth surface via sol-gel method

During the preparation of Bi2Sr2CaCu2O8+δ (Bi2212) superconducting thin films by sol-gel method, the complexing agent and sintering conditions can significantly influence the quality and the performance of thin film. In this study, Bi2212 thin films were prepared on single crystal SrTiO3 (001) substrate, and the phase purity, crystallinity, surface morphology and transport properties were studied particularly with different sintering temperature and time, complexing agent and its ratio to metal ions. Due to relatively low carbon content, tartaric acid (TA) as a complexing agent improved the film quality and transport properties compared with the traditional ethylenediamine tetraacetic acid (EDTA). When the complex ratios of TA to metal ions was 1:1, Bi2212 thin films exhibited good epitaxial properties, a high Bi2212 phase purity and a low surface roughness of 12.74 nm. Simultaneously, under these preparation condition, Bi2212 superconducting thin film showed a higher Tc, onset of 93.28 K.