Morphology control and piezoelectric response of Na0.5Bi0.5TiO3 synthesized via a hydrothermal method

Abstract

In this study, lead-free sodium bismuth titanate (Na_0.5Bi_0.5TiO₃, NBT) was synthesized using a hydrothermal method with processing temperatures of 100–180 °C and NaOH concentrations of 2–14 M. NBT spherical agglomerates of primary nanocubes, NBT nanowires and NBT microcubes were obtained and their morphologies exhibited a strong correlation with the synthesis conditions. NBT nanowires with a high aspect ratio were proven to be single-crystalline with a [110] growth direction by high-resolution TEM analysis. The in situ transformation process and dissolution–recrystallization mechanism were successfully used to explain the formation of different NBT morphologies. Domain structures and piezoelectric characteristics were systematically studied for NBT by piezoresponse force microscopy (PFM). Clear ferroelectric domain structures and obvious polarization switching behaviors were observed in all types of NBT. The NBT microcubes possessed a larger piezoresponse compared with the NBT spherical agglomerates and nanowires.