Core-shell structure and size effect in barium titanate nanoparticle

A quantitative core-shell structure model on the grain size effect of nano-BaTiO3 ceramics has been proposed on the basis of the Ginsburg–Landau–Devonshire thermodynamic theory. In this study, we have considered the existence of surface effects, which leads to the core-shell structure in BaTiO3 nanoparticles consisting of inner tetragonal core, gradient lattice strain layer, and surface cubic layer. The size effects on the spontaneous polarization, Curie temperature, c/a ratio, and electrocaloric and dielectric properties of BaTiO3 ferroelectric nanoparticle are successfully explained. Theoretical and experimental results for BaTiO3 nanoparticle are compared and discussed.