SrTiO₃ Nanocuboids from a Lamellar Microemulsion

Microemulsion science has provided a wide range of possibilities in materials fabrication. Here, we describe a novel approach to the synthesis of SrTiO 3 nanoparticles of different shapes from a microemulsion. We show that the microemulsion structure plays a critical role in the shape of the nanoparticles, with diffusion-limited growth when normal or reverse micelles are present to nanocuboids with a kinetic-Wulff shape in a lamellar microemulsion leading to nanocuboids. As determined by a combination of in situ small-angle X-ray scattering (SAXS) and wide-angle X-ray scattering (WAXS) as a function of temperature and ex situ high-angle annular dark field (HAADF) imaging, the as-prepared SrTiO 3 nanocuboids grow between three layers of water (3 × 1.1 nm) and two layers of oil (2 × 2.3 nm) leading to individual crystals which are uniformly 8 nm thick with somewhat greater lengths and widths.