Nano-sized cube-shaped single crystalline oxides and their potentials; composition, assembly and functions

Abstract Nanocrystals, especially with an anisotropic shape such as cubic, are candidates as building blocks for new bottom-up approaches to materials assembly, yielding a functional architecture. Such materials also receive attention because of their intrinsic size-dependent properties and resulting applications. Here, we report synthesis and characteristics of CeO 2 , BaTiO 3 and SrTiO 3 nanocubes and the ordered assemblies. The importance of shape as well as size distribution is clarified for the bottom-up development of 3D fine structures. CeO 2 nanocube assemblies with enhanced surface of specified crystal planes such as (1 0 0) and (1 1 1) would open new surface-dominant devices. BaTiO 3 and SrTiO 3 nanocubes with narrow size distributions and robust diversity in compositions were obtained. BaTiO 3 films made up of ordered nanocube assemblies were fabricated on various substrates by evaporation-induced self-assembly method. Regardless of the substrate, the nanocubes exhibited {1 0 0} orientations and a high degree of face-to-face ordering, which remained even after heat treatment at 850 °C. The supracrystal films exhibited distinct ferroelectric behaviors.