Particle Structure and Size Effect of Barium Titanate Nanoparticles

Abstract

Almost impurity-free, defect-free and dense barium titanate (BaTiO3) nanoparticles with various sizes from 20 to 430 nm were prepared using the 2-step thermal decomposition method. The crystal structures of these particles were investigated using a synchrotron radiation X-ray diffraction method. The observed diffraction pattern was analyzed using a new particle structure model. As a result, it is found that the BaTiO3 nanoparticles have composite structures composed of (a) tetragonal core, (b) gradient lattice strain layer and (c) cubic surface layer. Despite particle sizes, lattice parameters of tetragonal core and cubic surface layer were almost constant. The dielectric constant of BaTiO3 particle was estimated on basis of the new composite model, and the size effect for BaTiO3 nanoparticles was explained.