Synthesis of V${}_2$O${}_3$ Nanoplates

Abstract

Peculiar features exist in the stress-temperature phase stability diagram of V${}_2$O${}_3$ such as a first order phase transition between the paramagnetic insulating and metallic phases that ends with a critical point, quantum phase transition, and a triple point. These features remain largely unexplored and the exact nature of the phase transitions is not clear due to very limited control over the stress in bulk or film samples. Here, we show the synthesis of single-crystal V${}_2$O${}_3$ nanoplates for the first time using chemical vapor deposition via van der Waals epitaxy. Thickness of the V${}_2$O${}_3$ nanoplates range from a few to hundreds of nanometres and they can be mechanically exfoliated from the growth substrate. Using Raman spectroscopy on the nanoplates, we reveal that upon heating, V${}_2$O${}_3$ enters supercritical state for both tensiley strained and relaxed crystals with similar out-of-plane response. Transmission electron microscopy on V2O3 nanoplates hints the existence of a structural change when the crystals are heated. Our results show that V${}_2$O${}_3$ nanoplates should be useful for studying the physics of supercritical state and the phase stability of V${}_2$O${}_3$ to enable new horizons in applications.