New nonhydrolytic route to synthesize crystalline BaTiO₃ nanocrystals with surface capping ligands

A new nonhydrolytic route for the preparation of well-crystallized size-tunable barium titanate (BaTiO₃) nanocrystals capped with surface ligands is reported. Our approach involves: (i) synthesizing a “pseudo” bimetallic precursor, and (ii) combining the as-synthesized bimetallic precursor with a mixture of oleylamine with different surface coordinating ligands at 320 °C for crystallization and crystal growth. Different alcohols in the precursor synthesis and different carboxylic acids were used to study the effect of size and morphological control over the nanocrystals. Nanocrystals of barium titanate with diameters of 6–10 nm (capped with decanoic acid), 3–5 nm (capped with oleic acid), 10–20 nm (a nanoparticle and nanorod mixture capped with oleyl alcohol), and 2–3 nm (capped with oleyl alcohol) were synthesized, and can be easily dispersed into nonpolar solvents such as hexane or toluene. Techniques including x-ray diffraction, transmission electron microscopy, selected area electron diffraction, and high-resolution electron microscopy confirm the crystallinity and morphology of these as-synthesized nanocrystals.