Phase Change Materials with Tunable Phase Change Properties via Nanocomposite Designs

Phase change oxides have attracted extensive research interests because of significant functional property changes upon phase change and their potential device applications. In particular, vanadium dioxide (VO₂) has been widely studied as a strongly correlated Mott insulator which exhibits an intriguing metal-insulator switching upon cooling near 340 K (67 °C). The ultrafast and reversible first-order phase transition is coupled with a structural transition from rutile to monoclinic upon cooling. In this talk, a range of VO₂-based nanocomposite designs have been introduced with the goal to tune the phase transition temperature. A broad range of phase transition temperature has been demonstrated from as low as 301.8 K (VO₂– Au) to as high as 360.74 K in VO₂-Pt system. In addition, a unique Li-intercalation process has been introduced to tune the <i>T_c</i>. By controlling the relative potential with respect to Li/Li⁺ during the intercalation process, <i>T_c</i> of VO₂can be effectively and systematically tuned in the window from 326.7 K to 340.8 K. These demonstrations open up new approaches in tuning the VO₂ phase transition towards room temperature device applications and enables future real-time phase change property tuning.