Epitaxial Assembly Involved in Growth of BaTiO3 Nanocrystals under Hydrothermal Condition

Abstract

Epitaxial assembly involved in the formation of aggregates of single-crystalline barium titanate (BaTiO3) nanoparticles under hydrothermal condition is reported. The aggregates of BaTiO3 nanocrystals were synthesized by heating a mixture of barium hydroxide, Ba(OH)2, and titanium tetra-iso-propoxide, Ti(OiC3H7)4, with a molar ratio of 1.1 : 1 resolved in water–ethanol solutions at 150 °C for 2 h in autoclaves. The volume ratio of water/ethanol used as the solvent gives a significant influence on the amount of organic components contained in the precipitates after the reaction completed; a pure water solution left much organic components in the obtained BaTiO3 nanoparticles aggregates, whereas a 1:1 (in volume ratio) water–ethanol solution yielded aggregates of BaTiO3 nanoparticles with little organic components. Transmission electron microscopy (TEM) analyses provide definite evidence for the occurrence of epitaxial assembly of more than hundred BaTiO3 nanocrystals with sizes of 40–60 nm into an aggregation possessing crystallographically single-crystalline nature during the crystal growth under the hydrothermal condition.