Mg-doped VO2nanoparticles: hydrothermal synthesis, enhanced visible transmittance and decreased metal–insulator transition temperature

Abstract

This paper reports the successful preparation of Mg-doped VO₂ nanoparticles via hydrothermal synthesis. The metal–insulator transition temperature (T_c) decreased by approximately 2 K per at% Mg. The T_c decreased to 54 °C with 7.0 at% dopant. The composite foils made from Mg-doped VO₂ particles displayed excellent visible transmittance (up to 54.2%) and solar modulation ability (up to 10.6%). In addition, the absorption edge blue-shifted from 490 nm to 440 nm at a Mg content of 3.8 at%, representing a widened optical band gap from 2.0 eV for pure VO₂ to 2.4 eV at 3.8 at% doping. As a result, the colour of the Mg-doped films was modified to increase their brightness and lighten the yellow colour over that of the undoped-VO₂ film. A first principle calculation was conducted to understand how dopants affect the optical, Mott phase transition and structural properties of VO₂.