Hydrothermal synthesis of nanocrystalline BaTiO 3 particles and structural characterization by high-resolution transmission electron microscopy

Abstract

Nanocrystalline BaTiO 3 (BT) particles were synthesized via hydrothermal method, and their microstructure was characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), selected area electron diffraction (SAED), and high-resolution TEM (HRTEM). The results show that the BT nanoparticles remain a metastable cubic structure at room temperature, as revealed by XRD and SAED. Such an abnormal crystallographic phenomenon was caused by the lattice defects such as OH − defects and barium vacancies. The BT nanoparticles exhibit a spherical morphology with an average grain size of 70 nm, and narrow particle size distribution. HRTEM images of individual particles indicate that the BT nanoparticles have a good crystallinity and smooth surfaces. However, dark-field TEM images revealed high strains in BT nanoparticles, which were probably resulted from the surface defects. Anti-phase boundaries were also observed in some BT nanoparticles, which were formed by the intersection of two crystalline parts with a relative displacement from each other by 1 2 d 100 or 1 2 d 111 , as revealed by HRTEM images. Some local dark TEM contrast observed, near the pure edge dislocations with Burgers vector value of d 110, was due to the existence of local strains around the pure edge dislocations.