Non-equilibrium Spark Plasma Reactive Doping Enables Highly Adjustable Metal-to-Insulator Transitions and Improved Mechanical Stability for VO2

Abstract

Although vanadium dioxide (VO2) exhibits the most abrupt metal-to-insulator transition (MIT) properties near room temperature, the present regulation of their MIT functionalities is insufficient owing to the high complexity and susceptibility associated with V4+. Herein, we demonstrate a spark plasma-assisted reactive sintering approach to simultaneously achieve in situ doping and sintering of VO2 within a largely short period (∼10 min). This enables high convenience and flexibility in regulating the electronic structure of VO2 via dopant elements covering Ti, W, Nb, Mo, Cr, and Fe, leading to a wide adjustment in their MIT temperature (TMIT) and basic resistivity (ρ). Furthermore, the mechanical strength of the doped VO2 is meanwhile largely improved via the compositing effect of the high-melting-point dopant oxide. The high adjustability in MIT properties and improved mechanical properties further pave the way toward practical applications of VO2 in power electronics, thermochromism, and infrared camouflage.