Structural Explanation of the Dielectric Enhancement of Barium Titanate Nanoparticles Grown under Hydrothermal Conditions

When synthesized under certain conditions, barium titanate (BaTiO3, BTO) nanoparticles are found to have the non-thermodynamic cubic structure at room temperature. These particles also a several-fold enhanced dielectric constant, sometimes exceeding 6000, and widely used in thin-layer capacitors. A hydrothermal approach is synthesize BTO nanocrystals, which characterized by range of methods, including X-ray Rietveld refinement Williamson–Hall approach, revealing presence significant inhomogeneous strain associated with phase. However, pair distribution function measurements clearly show local lower symmetry than cubic. This apparent inconsistency resolved examining 3D Bragg coherent diffraction images selected existence ≈50 nm-sized domains, interpreted as tetragonal twins, yet cause average crystalline appear The ability these twin boundaries migrate influence electric fields explains anomaly for nanocrystalline