Topochemical reaction of SrTiO3 platelet crystals based on Sr3Ti2O7 platelet precursor in molten salt synthesis process

Molten salt synthesis (MSS) is an effective method to prepare anisotropic shaped single crystals. In this study strontium titanate (SrTiO3) (ST) platelet crystals were successfully synthesized based on Sr3Ti2O7 (S3T2) platelet precursor in MSS process. The objective is to identify the formation mechanism of SrTiO3 platelet crystals based on Sr3Ti2O7 platelet precursor. During the synthesis process of Sr3Ti2O7 and SrTiO3 crystals, the final sizes are strongly influenced by the sorts of alkali chloride medium. Sr3Ti2O7 and SrTiO3 crystals with 30–50 μm in edge length and ∼2 μm in thickness are obtained in KCl medium. The conversion of SrTiO3 platelet crystals from Sr3Ti2O7 platelet precursor is a topochemical process, including diffusion of Sr and O atoms, and reconstruction of SrTiO3 blocks. In the topochemical process, TiO2 is the driving force of diffusion of Sr and O atoms from SrO layer in Sr3Ti2O7, which reacts with dissociative Sr2+ and O2− to form SrTiO3 in different positions: deposited at interior pores and surface of Sr3Ti2O7, and dispersed in molten salt medium.