Ferroelectric mesocrystalline BaTiO3/Bi0.5K0.5TiO3 nanocomposites: Topochemical synthesis, enhanced piezoelectric and dielectric responses

Abstract

Ferroelectric mesocrystalline nanocomposite is a promising nanomaterial for enlarged piezoelectric response and dielectric response obtained using lattice strain engineering. In this study, mesocrystalline BaTiO3/Bi0.5K0.5TiO3 (BT/BKT) nanocomposites were prepared via a two-step topochemical process. In the first step, a platelike layered titanate H1.07Ti1.73O4·nH2O (abbreviated as HTO) precursor was solvothermally treated in a Ba(OH)2 solution to synthesize a BaTiO3/HTO (abbreviated as BT/HTO) nanocomposite. In the second step, a BT/HTO-Bi2O3–K2CO3 mixture was heat-treated to obtain BT/BKT nanocomposite. The reactions occurring in the formation of BT/BKT nanocomposite are topochemical reactions. Nanostructural analysis shows that the BT/BKT nanocomposite is constructed from well-aligned [110]-oriented BT nanocrystals and [001]-oriented BKT nanocrystals. In the nanocomposite BT(001)/BKT(100), heteroepitaxial interface is formed, introducing a lattice strain at the interface owing to their lattice mismatch. The BT/BKT nanocomposite exhibits much larger d33* and εr values than those of individual BT and BKT mesocrystals. The enlarged piezoelectric and dielectric responses show the potential application of lattice strain engineering to mesocrystalline nanocomposites for high-performance lead-free piezoelectric materials.