Recent progress in the phase-transition mechanism and modulation of vanadium dioxide materials

Metal-to-insulator transition (MIT) behaviors accompanied by a rapid reversible phase transition in vanadium dioxide (VO2) have gained substantial attention for investigations into various potential applications and obtaining good materials to study strongly correlated electronic behaviors in transition metal oxides (TMOs). Although its phase-transition mechanism is still controversial, during the past few decades, people have made great efforts in understanding the MIT mechanism, which could also benefit the investigation of MIT modulation. This review summarizes the recent progress in the phase-transition mechanism and modulation of VO2 materials. A representative understanding on the phase-transition mechanism, such as the lattice distortion and electron correlations, are discussed. Based on the research of the phase-transition mechanism, modulation methods, such as element doping, electric field (current and gating), and tensile/compression strain, as well as employing lasers, are summarized for comparison. Finally, discussions on future trends and perspectives are also provided. This review gives a comprehensive understanding of the mechanism of MIT behaviors and the phase-transition modulations. Smart coatings that alter their electrical properties on demand can be created from shape-shifting vanadium dioxide (VO2) crystals. Xun Cao from Shanghai Institute of Ceramics, Chinese Academy of Sciences in Shanghai and co-workers review efforts to understand the mechanisms that enable VO2 to rapidly switch between two crystal states — one with metallic conductivity, the other insulating—at near-room temperature conditions. Theoretical calculations and nanoscale experiments reveal that VO2 transitions are triggered by a combination of interactions between electrons and atoms in the crystal lattice, and through forces that cause electrons to avoid each other. Several innovative methods of manipulating the VO2 switching temperature have emerged including foreign element additions, laser irradiation, and controlled substrate bending. The sensitivity of VO2 transitions to mechanical stress has inspired proposals for ultrafast response breath sensors and artificial skin. In this article, we review the prototypical phase-transition material-VO2, which undergoes structure and conductivity changes simultaneously. The recent progresses in the transition mechanism are also discussed. Besides, this work gives a comprehensive understanding of the phase-transition modulations, such as element doping, electric field (current and gating) and tensile/compression strain, as well as employing laser.