Low-Temperature Synthesis of SrBi2Ta2O9 Ferroelectric Thin Films through the Complex Alkoxide Method: Effects of Functional Group, Hydrolysis and Water Vapor Treatment

SrBi2Ta2O9 (SBT) ferroelectric thin films were synthesized at lower temperatures by the sol–gel method using complex alkoxides. The effects of the complex alkoxide functional group, the amount of water used in hydrolysis, and a mixture of water vapor and oxygen flow during calcination, on the crystallization, the microstructural development, and the ferroelectric properties of the SBT thin films were addressed. The film which was deposited from complex alkoxide solutions and then calcined at 250°C in the mixture, contained a relatively smaller amount of the remaining alkoxy groups, and therefore, crystallized to SBT via rapid thermal annealing at temperatures below 500°C in an oxygen flow. Crystallinity improved significantly and the microstructure was able to develop up to 650°C. Remarkable grain growth was observed particularly in the SBT thin film deposited from the ethanolic solution of the complex ethoxide. Film annealed at 650°C exhibited the saturated P–E hysteresis loop and improved endurance behavior.