Synthesis of BaTiO3–CaTiO3 and BaTiO3–SrTiO3 Core–Shell Nanocubes via the Surface Reconstruction of BaTiO3 Nanocubes

BaTiO 3 –CaTiO 3 and SrTiO 3 –BaTiO 3 core–shell nanocubes were synthesized through the surface reconstruction of BaTiO 3 nanocubes, which involved the reaction of titanium oxide with Ca(OH) 2, Sr(OH) 2, or Sr(OH) 2 ·8H 2 O in water at 100 °C. The core–shell structure comprised a BaTiO 3 nanocube core and a CaTiO 3 or SrTiO 3 shell. The outermost layer with a perovskite structure also comprised CaTiO 3 or SrTiO 3, and its thickness was several hundred picometers. The thinnest layer was constructed of only one layer of CaTiO 3 or SrTiO 3 . This is the first presented work on a core–shell nanocube with the outermost layer consisting of only CaTiO 3 or SrTiO 3 surrounding the BaTiO 3 nanocube. The shells of CaTiO 3 and SrTiO 3 comprise a layer thickness of only one unit cell of ∼0.4 nm (400 pm). Thus, we demonstrate new research on nanocube surfaces on the picometer scale.