Ferroelectric and dielectric properties of sub-10 nm BaTiO₃ nanoparticles

BaTiO₃ has been investigated nearly several decades due to its excellent ferroelectric and dielectric properties. However, the property evolution of BaTiO₃ with a particle size of sub-10 nm is still unclear because of the difficulty during the fabrication and characterization. Here, a series of BaTiO₃ nanoparticles with the average particle sizes of 2.8, 4.5 and 8.1 nm are achieved, and their phase structure, ferroelectric and dielectric properties are skillfully characterized. With the particle size decreasing from 8.1 to 2.8 nm, the nanoparticles show a declining non-centrosymmetry, nonlinear response, ferroelectricity and dielectric constant. Nevertheless, the 2.8 nm BaTiO₃ nanoparticles still possess observable second harmonic generation, ferroelectric polarization switching behavior and butterfly loop, showing weak but distinguishable ferroelectricity. This research depicts a detailed ferroelectric and dielectric property evolution in sub-10 nm BaTiO₃ nanoparticles, which provides theoretical basis and promising candidate for the future ferroelectric applications.