Predicted rebound effects of insulator-metal transition temperature in tungsten doped VO2 via first-principles method

Abstract

A first-principles study of insulator-metal transitions (IMTs) in the W-doped monoclinic phase and the rutile phase of VO2 has been carried out. The doping concentration was achieved by substituting atoms of vanadium by tungsten in various supercells of monoclinic and rutile phased VO2. We found a fascinating rebound behavior of transition temperature, which exhibited an unobstructed relation to crystal and electronic structures. The results showed that by increasing the doping concentration of W into VO2, the IMT tuned to lower temperature at the beginning and then anomalously shifted to a higher temperature. This rebound effect was confirmed by the calculated V-atomic shift dV, V-atomic charge transfer Δq, and density of states. We attributed this effect to the consequences of "off-chain" and "in-chain" substitutive doping of W atoms. This alteration affects the capability of the VO2 crystal to tolerate the perturbations caused by dopants, and, as an upshot, the IMT properties of VO2 depressed initially and recovered later. This unique behavior might have great applications for smart windows, sensors, and other switching devices.