Composite structure and size effect of barium titanate nanoparticles

Nanostructures of barium titanate (BaTiO3) nanoparticles were analyzed using a composite structure model. It was found that BaTiO3 nanoparticles had a composite structure consisting of (i) inner tetragonal core, (ii) gradient lattice strain layer (GLSL), and (iii) surface cubic layer. The crystal structure of each region did not depend on particle size while the volume fraction of the GLSL and the surface cubic layer increased with decreasing the particle size. These results suggested that the size effect of BaTiO3 nanoparticles originated from the composite structure.