Low-Temperature Reaction of Aurivillius Phases with Halides

Kijima et al. [T. Kijima, S. Kimura, Y. Kawahara, K. Ohe, M. Yada, and M. Machida, J. Solid State Chem. 146, 60 (1999)] recently reported a reaction between Bi4Ti3O12 and LiI in the presence of iodine at 350°C. Their product was never obtained free of Bi4Ti3O12, but their claim was that their product was Bi4Ti3O12 intercalated with I and Li. We have repeated this reaction and found conditions under which the reaction goes to completion, i.e., Bi4Ti3O12 is completely consumed. The dominant crystalline product is apparently identical to the product reported by Kijima et al. However, we conclude that no intercalation of Bi4Ti3O12 has occurred. This dominant crystalline phase is in fact BiOI. The remainder of the product is poorly crystalline. Analogous reactions occur at low temperature using other halides such as NaCl and other Aurivillius phases such as Bi2WO6.