Topological relations and piezoelectric responses of crystal-axis-oriented BaTiO3/CaTiO3 nanocomposites

Abstract

2D crystal-axis-oriented mesocrystalline BaTiO₃/CaTiO₃ (BT/CT) nanocomposites with high-density heteroepitaxial interfaces were synthesized by a two-step solvothermal soft chemical process. The nanostructures, formation mechanism, topological relations between the BT and CT, and piezoelectric responses of the nanocomposites were investigated. The mesocrystalline nanocomposites are polycrystals constructed from crystal-axis-oriented BT and CT nanocrystals with the same crystal-axis orientation, respectively. The directions of the [001] and [1−10] of crystalline BT correspond to the directions of the [0−10] and [100] of crystalline CT, respectively. The mesocrystalline nanocomposites were formed via an in situ topochemical mesocrystal conversion mechanism. The density of the artificial BT/CT heteroepitaxial interface in these mesocrystalline nanocomposites can be adjusted by regulating the fraction of BT and CT in the nanocomposites. The mesocrystalline BT/CT nanocomposite with the composition close to BT/CT = 1/1 presents a large piezoelectric response owing to the lattice strain derived from its heteroepitaxial interfaces with the high density in the nanocomposite.