Highly depressed temperature-induced metal-insulator transition in synthetic monodisperse 10-nm V2O3 pseudocubes enclosed by {012} facets

Abstract

Monodisperse 10-nm V₂O₃ pseudocubes enclosed by {012} facets were successfully synthesized for the first time via a novel and facile solvothermal method, offering the first opportunity to elucidate the effect of finite-size and facet on the temperature-induced reversible metal-insulator transition (MIT) behavior of V₂O₃. Very excitingly, the transition temperature of these V₂O₃ pseudocubes drastically depressed from 133 K to 36 K and their corresponding hysteresis width highly narrowed from 17 K to 5 K, compared to the MIT behaviors of other irregular V₂O₃ particles with average sizes of 10 nm, 20 nm, 40 nm, 170 nm and 2 μm. Notably, the size-related surface energy, grain boundary connectivity and volume expansion could be used to account for their strong size-dependent transition temperature and hysteresis width. Moreover, the improved grain boundary connectivity associated with well-defined {012} facets enabled these 10-nm V₂O₃ pseudocubes to display a 10 times higher resistivity jump (at the order of 10⁵) and by nearly one-half smaller hysteresis width of 5 K than the irregular 10-nm V₂O₃ particles with randomly exposed facets, directly evidencing the pronounced influence of facets on the MIT behavior. Briefly, the present work not only develops an effective strategy for synthesizing high-quality nanocrystals but also provides an excellent platform to investigate the size- and facet-dependent temperature-induced MIT behavior, enabling to design smart electrical switching nano-devices in the rapidly developing ultra-low temperature field.