Generic Synthetic Route to Monodisperse Sub-10 nm Lanthanide Oxide Nanodisks: A Modified Digestive Ripening Process

The development of generic methods to synthesize monodisperse nanomaterials is one of the most critical issues in the current research field of nanomaterial synthesis. In this work, we demonstrate for the first time that a digestive ripening process can produce monodisperse sub-10 nm lanthanide oxide nanodisks. Moreover, we show that nanodisks of nine different lanthanide oxides can be synthesized under the same reaction conditions. The successful synthesis is realized by employing a hot injection step to induce a single nucleation event and by introducing transition metal ions to delicately define the size and shape of the nanodisks in the digestive ripening process. Among the various nanodisks, Gd₂O₃, Dy₂O₃, and Ho₂O₃ nanodisks show promising magnetic properties as magnetic resonance imaging contrast agents. We expect that this novel synthetic route can be extended to various nanomaterials, including metallic and semiconducting nanocrystals.