Three‐Dimensional Imaging of the Structural Phase Transition in a Single Vanadium Dioxide Nanocrystal

Vanadium dioxide (VO2) is a strongly correlated material that exhibits a number of structural phase transitions (SPT) near to room temperature of considerable utility for various technological applications. When reduced to the nanoscale, a foreknowledge of surface and interface properties of VO2 during the SPT can facilitate the development of devices based on VO2. Herein, it is shown that Bragg coherent X‐ray diffractive imaging (BCDI) combined with machine learning is an effective means to recover three‐dimensional images of a single VO2 nanocrystal during a temperature‐induced SPT from a room‐temperature monoclinic phase to a high‐temperature rutile phase. The findings reveal the coexistence of multiple phases within the nanocrystal throughout the transition, along with missing density which indicates the presence of a newly formed rutile phase. Bragg coherent X‐ray diffractive imaging (BCDI) when combined with machine learning provides three‐dimensional visualization of a single VO2 nanocrystal during the temperature‐induced structural phase transition from monoclinic to rutile phase. This study reveals the coexistence of multiple phases and shows missing density linked to the formation of a new rutile phase.