Intermediate phases formation during the synthesis of Bi4Ti3O12 by solid state reaction

In this work, the formation of Bi₄Ti₃O₁₂ by solid state reaction from Bi₂O₃ and TiO₂ starting powders has been studied. The Bi₄Ti₃O₁₂ formation occurs through an intermediate Bi₁₂TiO₂₀ sillenite phase formed at temperatures sligthly over 300 °C. This sillenite phase is stable up to ∼750 °C, but in the presence of TiO₂ reacts to form Bi₄Ti₃O₁₂ at temperatures >500 °C. Raman spectroscopy has been used to evidence the amorphization of TiO₂, demonstrating that the Bi₄Ti₃O₁₂ formation occurs through the reaction of sillenite Bi₁₂TiO₂₀ and TiO₂.