Aqueous sol-gel synthesis of epitaxial Bi2212 thin films enabled by OP-10 surfactant modification

This study employed metal nitrates as precursors, glycine as a complexing agent, and deionized water as the solvent to synthesize Bi2Sr2CaCu2O8+x (Bi2212) thin films on SrTiO3(100) single-crystal substrates using the sol-gel method. Dodecylphenol polyoxyethylene ether (OP-10) was introduced as a surfactant to enhance the wettability of the Bi2212 sol on the single-crystal substrate, leveraging its excellent miscibility with the sol. The influence of OP-10 modification was examined on both the substrate wettability and the key properties of Bi2212 films, including crystallinity, texture, surface morphology, and superconducting performance. The results demonstrate that OP-10 modification significantly improves the wettability of the Bi2212 sol on SrTiO3(100) single-crystal substrates. Consequently, Bi2212 superconducting films with smooth, continuous surfaces and (00l) epitaxial growth were successfully achieved on SrTiO3(100) substrates. The in-plane orientation relationship was determined to be Bi2212[100](001)//SrTiO3[011](100). The surface roughness of these films remained around 15 nm. All prepared films displayed excellent superconducting properties. This work establishes a valuable research foundation for the preparation of multicomponent functional oxide thin films via the aqueous sol-gel route.