Ion-exchangeable thin films derived from a layered titanate, Cs0.68Ti1.83□0.17O4 (□:vacancy)

Abstract

A proton-exchanged layered titanate prepared from Cs_0.68Ti_1.83□_0.17O₄ was exfoliated in ethylamine solution through an ion-exchange of Cs⁺ to ethylammonium ion (C₂H₅NH₃⁺) followed by infinite swelling. Thin films composed of the exfoliated layered titanate sheets with ethylammonium ions in the interlayer space showed ion-exchange capability; it was possible to replace the ethylammonium ions with various cations in aqueous chloride solutions without destroying the thin film structure. The original Cs_0.68Ti_1.83□_0.17O₄ thin film was replaced by a Cs⁺-exchanged film, which showed thermal stability up to 873 K. Homogeneously colored thin films were also prepared by intercalation of dye molecules using alkylammonium-intercalated precursors. From transmission electron microscopy (TEM) observation, it was found that the exfoliated sheets were not monolayers but consisted of about 10 layers.