Theoretical study on the tungsten-induced reduction of transition temperature and the degradation of optical properties for VO2

Abstract

We have studied the effect of the doped tungsten on the phase transition temperature and the optical properties between the monoclinic phase and the rutile phase of VO2 by performing first-principles calculations. It is found that the introduction of tungsten (W) significantly decreases the transition temperature between the rutile VO2 and the monoclinic VO2, with reducing the energy difference between the two phases. Meanwhile, our calculations indicate that the doped W lowers the infrared light transmittance of the monoclinic VO2, being consistent with the experimental observations. The nature about the reduction of the transition temperature and the change of the optical properties arising from the W dopants is revealed. Our results are valuable for application of VO2 as an optical energy material in future.

Direct evidence of tungsten clustering in W0.02V0.98O2 thin films and its effect on the metal-to-insulator transition

“…39 It has already been reported that the introduction of the W dopants into the R phase of VO2 can induce a structural distortion and notably a V-V pairing in the chain where the W is located, but mostly the W dopants were considered in a diluted configuration. 29,30,34 Our HAADF observations and ab-initio simulations demonstrate the existing of the W clustering mechanism, which reduces the structural distortion effect, making it more localized around the dopant, while maintaining the further area in a better tetragonal feature. This structural effect might have implication on the MIT transition.…”

“…Corresponding first principle calculations also suggest that these structural alterations can reduce the energy difference between the two phases and therefore decrease the transition temperature. 33,34 Figure 1. Layout of the V-V chains along (a) the c axis of the R phase and (b) the corresponding a axis of the M1 phase.…”

“…10 K/GPa, 27, 28 the internal stress due to the W dopant is also expected to act similarly. [29][30][31][32][33][34] The analysis of the local structures around both V and W dopant has been performed by several groups, [29][30][31][32][33] mostly by synchrotron Extended X-Ray Absorption Fine Structure (EXAFS) method. These works report that the VO2 local structure is strongly altered by the W dopants: in the M1 phase, W dopants drive the de-twisting and decoupling of their nearby V-V pairs, increase the symmetry toward the R structure and act as nucleation centers to facilitate the structure transition; otherwise in the R phase, the W dopants induce the dimerization of the V-V chains.…”

Hydrogen-doping induced reduction in the phase transition temperature of VO2: a first-principles study

“…7 Focusing on this issue, various studies have been conducted to tailor T c by means of element doping, 8 external strain, 9 photon irradiation 10 or a combination of these factors. [12][13][14] For example, a pronounced reduction in the T c of À23 K/at% and À11 K/at% (where at% is the atomic percent) can be achieved by W doping and Mo doping, respectively. [12][13][14] For example, a pronounced reduction in the T c of À23 K/at% and À11 K/at% (where at% is the atomic percent) can be achieved by W doping and Mo doping, respectively.…”

Formation energies of intrinsic point defects in monoclinic VO2 studied by first-principles calculations

“…32,33 The value of U eff was chosen as 3.4 eV in this work, which has been shown to give a good description of the properties of vanadium dioxide. 34,35 The valence electron configurations are O-2s 2 2p 4 and V-3d 3 4s 2 for the two elemental constituents. The cut-off energy was 520 eV for the plane-wave basis.…”