Fabrication and topchemical transformation mechanism of PbTiO3 microplatelets. Issue 5 (1st March 2023) - Li, Leilei
Abstract: Two-dimensional platelets of the perovskite-structured PbTiO3 were synthesized from a layer-structured PbBi4 Ti4 O15 precursor, using a topochemical microcrystal route. The PbBi4 Ti4 O15 precursor showed a high aspect ratio with an average size of ∼7.74 μm and thickness of ∼0.29 nm. Later, PbTiO3 platelets coexisting with Pb4 Bi4 Ti7 O24 mesophase were obtained, which had a more stable Aurivillius structure and was difficult to completely convert to the perovskite structure during topochemical microcrystal conversion. The reason that the Pb4 Bi4 Ti7 O24 mesophase coexisted in PbTiO3 platelets was deeply discussed. Both the crystal structure difference between the unit cell parameters for (Pb4 Bi2 Ti7 O22 ) 2- and the thickness for the (Bi2 O2 ) 2+ layer, and the stability of (Bi2 O2 ) 2+ layer were used to analyze the existence of Pb4 Bi4 Ti7 O24 phase. However, the result showed that the stability of (Bi2 O2 ) 2+ layer was the dominant reason, because the [OBi4 ]/[OPb4 ] tetrahedron formed in the (Bi2 O2 ) 2+ layer due to the similar chemical properties of Pb 2+ and Bi 3+ . The work provided deep theoretical guidance to fabricate anisotropic perovskite platform-based topchemical microcrystal conversion mechanisms.