Synthesis of Ba_0.6Sr_0.4TiO₃ platelet crystals based on Bi₄Ti₃O₁₂ precursor by topochemical microcrystal conversion

A-site complex perovskite Ba_0.6Sr_0.4TiO₃ (BST) platelet microcrystals were successfully synthesized using a two-step Molten Salt Synthesis (MSS) method based on Bi₄Ti₃O₁₂ platelet precursor. During the synthesis process, the calcination temperature and the soaking time strongly influence on the morphology and particle size of BST. The optimal temperature for calcination is 740 °C. In addition, the increasing edge length with 5 μm–11.5 μm and thickness with less than 0.25 μm of BST platelets are obtained under the condition of rising soaking time from 5 h to 20 h, which can be used for preparing highly textured ceramics and microwave devices. Finally, the mechanism of topochemical microcrystal conversion reaction between BaCO₃-SrCO₃ mixture and Bi₄Ti₃O₁₂ was discussed.