Oleic acid, a typical 18-carbon chain, has been widely used as a surfactant to fabricate colloidal nanocrystals. In previous work, we discovered a lamellar microemulsion strategy to fabricate sub-20nm SrTiO3 nanocuboids formed by oleic acid and oleate species. Here, we demonstrate both (i) the general synthesis with lamellar microemulsions of a family of cubic BaxSr1-xTiO3 crystalline nanocuboids with uniform size and tunable composition and (ii) subsequent their assembly into two-dimensional arrays by bent oleic acid in nonpolar solvent. Lower aspect ratio nanocuboids are encircled by four adjacent nanocuboids which results in a uniform direction self-assembly array, whereas higher aspect ratio nanocuboids are encircled by five or six adjacent nanocuboids leading to a multi-direction self-assembly array. The measured inter-particle distance (2.4nm) of adjacent nanoparticles in an array is less than the distance of a double oleic acid layer (3.4nm). Based on calculations of the interfacial free energy and contact angle, we propose the hydrophobic, hydrocarbon-terminated groups of bent oleic acid from adjacent nanocuboids are situated closely but do not overlap.

Role of bent oleic acid: From synthesis to assembly of perovskite nanocuboid 2D arrays

248th National Meeting (2014)

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