Formation Mechanism of (001) Oriented Perovskite SrTiO3 Microplatelets Synthesized by Topochemical Microcrystal Conversion

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• 作者：Yunfei Chang ; Huanpo Ning ; Jie Wu ; Shantao Zhang ; Tianquan L眉 ; Bin Yang ; Wenwu Cao
• 刊名：Inorganic Chemistry
• 出版年：2014
• 出版时间：October 20, 2014
• 年：2014
• 卷：53
• 期：20
• 页码：11060-11067
• 全文大小：483K
• ISSN：1520-510X

文摘

To develop a better understanding of the mechanism responsible for topochemical microcrystal conversion (TMC) from Aurivillius SrBi₄Ti₄O₁₅ precursors to perovskite SrTiO₃ microplatelets, compositional/structural evolutions, morphological development, and reaction interface evolution of the (001) oriented SrBi₄Ti₄O₁₅ microplatelets were investigated during the conversion process. The results show that multiple topotactic nucleation events of SrTiO₃ occurred directly on the surfaces of SrBi₄Ti₄O₁₅ above 700 掳C, while reacting zones of intermediate phase(s) with less Bi³⁺ contents were observed to form in the interior of SrBi₄Ti₄O₁₅. Extensive exfoliation of the precursors occurred generally parallel to the (001) surfaces above 775 掳C. At 950 掳C, the original single-crystal SrBi₄Ti₄O₁₅ platelet was replaced by a polycrystalline aggregate consisting of (001) aligned SrTiO₃ crystallites and poorly crystallized intermediate phase(s). With further increasing the temperature or holding time, the SrTiO₃ phase formed from related intermediate phase(s), and the aligned crystallites were sintered to form dense SrTiO₃ with strong (001) orientation. The obtained SrTiO₃ microplatelets preserved the shape of SrBi₄Ti₄O₁₅ and show high chemical and phase purity. This TMC mechanism has general applicability to a variety of compounds and will be very useful for the design and synthesis of novel anisotropic perovskite crystals with high quality in the future.