Fabrication and topchemical transformation mechanism of PbTiO3 microplatelets

Two-dimensional platelets of the perovskite-structured PbTiO3 were synthesized from a layer-structured PbBi4-Ti4O15 precursor, using a topochemical microcrystal route. The PbBi4Ti4O15 precursor showed a high aspect ratio with an average size of-7.74 mu m and thickness of-0.29 nm. Later, PbTiO3 platelets coexisting with Pb4Bi4-Ti7O24 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 Pb4Bi4-Ti7O24 mesophase coexisted in PbTiO3 platelets was deeply discussed. Both the crystal structure difference be-tween the unit cell parameters for (Pb4Bi2Ti7O22)2-and the thickness for the (Bi2O2)2+ layer, and the stability of (Bi2O2)2+ layer were used to analyze the existence of Pb4Bi4Ti7O24 phase. However, the result showed that the stability of (Bi2O2)2+ layer was the dominant reason, because the [OBi4]/[OPb4] tetrahedron formed in the (Bi2O2)2+ layer due to the similar chemical properties of Pb2+ and Bi3+. The work provided deep theoretical guidance to fabricate anisotropic perovskite platform-based topchemical microcrystal conversion mechanisms.

Automated summary

Two-dimensional platelets of perovskite-structured PbTiO3 were synthesized using a topochemical microcrystal route with a layer-structured PbBi4-Ti4O15 precursor. The precursor had a high aspect ratio with an average size of 7.74 μm and thickness of 0.29 nm. The obtained PbTiO3 platelets coexisted with Pb4Bi4-Ti7O24 mesophase, which had a more stable Aurivillius structure and was difficult to fully convert into the perovskite structure during topochemical microcrystal conversion. The reason for the coexistence of Pb4Bi4-Ti7O24 mesophase in PbTiO3 platelets was discussed.