title: Formation mechanism of (001) oriented perovskite SrTiO3 microplatelets synthesized by topochemical microcrystal conversion.
abstract: 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 °C, while reacting zones of intermediate phase(s) with less Bi(3+) contents were observed to form in the interior of SrBi4Ti4O15. Extensive exfoliation of the precursors occurred generally parallel to the (001) surfaces above 775 °C. At 950 °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.
authors.affiliation: Condensed Matter Science and Technology Institute & School of Science, Harbin Institute of Technology , Harbin 150080, China.
authors.forename: Yunfei
authors.initials: Y
authors.lastname: Chang
authors.forename: Huanpo
authors.initials: H
authors.lastname: Ning
authors.forename: Jie
authors.initials: J
authors.lastname: Wu
authors.forename: Shantao
authors.initials: S
authors.lastname: Zhang
authors.forename: Tianquan
authors.initials: T
authors.lastname: Lü
authors.forename: Bin
authors.initials: B
authors.lastname: Yang
authors.forename: Wenwu
authors.initials: W
authors.lastname: Cao