Theoretical study of the electronic and optical properties of rare-earth (RE = La, Ce, Pr, Nd, Eu, Gd, Tb)-doped VO2 nanoparticles

Abstract

Vanadium dioxide (VO2) is an important thermochromic material due to its reversible metal-insulator transition at 340 K. However, the high phase transition temperature of VO2 prevents its practical application in smart windows. Here, we use first-principles calculations to study the effect of rare-earth (RE = La, Ce, Pr, Nd, Eu, Gd, Tb) dopants on the variation of the local octahedral volumes, lattice distortion of VO2 and dimerization of the V-V chain in VO2. Interestingly, Tb and La dopants with a concentration of 3.1 at.% decreased the phase transition temperature of VO2 to 206 K and 225 K, respectively. Moreover, three factors, including the V-V chain change, distortion of the REO6 octahedron, and formation of impurity states contributed by RE-f states, assist the phase transition of VO2. Additionally, the incorporation of an RE dopant scaled the band gap of VO2 and further tuned its near-IR absorption. These findings provide novel insights and guidance on chemically tailoring the phase transition of VO2.