Synthesis of Thermochromic W‐Doped VO₂ (M/R) Nanopowders by a Simple Solution‐Based Process

Abstract

Thermochromic W-doped VO2nanopowders were prepared by a novel and simple solution-based method and characterized by a variety of techniques. We mainly investigated the effect of tungsten dopant on the structural properties and phase transition ofV1-xWxO2. The as-obtained nanopowders with tungsten content of ≤2.5 at% can be readily indexed as monoclinic VO2(M) while that of 3 at% assigned into the rutile VO2(R). The valence state of tungsten in the nanopowders is +6. TEM and XRD results show that the substitution of W atom for V in VO2results in a decrease of thedspace of the (011) plane. The phase transition temperature is determined by differential scanning calorimetry (DSC). It is found, for the first time, that the reduction of transition temperature reaches to 17 K per 1 at% of W doping with the tungsten extents of ≤1 at%, but only 9.5 K per 1 at% with the tungsten extents of >1 at%. The reason of this arises from the difficulty of the formation ofV3+-W4+andV3+-W6+pairs by the increasing of W ions doping in theV1-xWxO2system.

Superior electrochemical properties of rutile VO2-carbon composite microspheres as a promising anode material for lithium ion batteries

“…These VO 2 polymorphs show the same stoichiometry; however, their structures are very different [18,19]. The oxygen octahedra in the rutile structured VO 2 (R) and in monoclinic VO 2 (M) can be aligned along two perpendicular directions [20,21]. However, the oxygen octahedra can be mainly aligned along only one direction in the metastable VO 2 (B) and VO 2 (A) [22].…”

“…Some lower valence VO x compounds including VO 2 and V 2 O 3 could also be used as anode materials because of their good lithium ion storage properties [16,17]. Vanadium dioxide exists as four polymorphs, VO 2 (R), VO 2 (M), VO 2 (B), and VO 2 (A) [18][19][20][21]. These VO 2 polymorphs show the same stoichiometry; however, their structures are very different [18,19].…”

Oxide Electronics and Vanadium Dioxide Perspective: A Review

“…Also, memory effects due to the electric field induced Mott transition (in cerium oxide particularly) have been studied in [140]. In addition, vanadium dioxide can be used as a material for thermochromic coatings, optical filters and controllers, sensors, bolometers, sensitive elements for RF and THz radiation control, micro-electromechanical systems, plasmonic modulators, access diodes in oxide RеRAM and many other optical and electronic devices [47], [83], [84], [134], [141]- [166]. Many authors note that the high operation lifetime of VO 2 -based devices (e.g.…”

“…6) or, as suggested in [58], to the Mott insulator state. It should be noted that a huge number of works on doping (especially, by tungsten) amongst all the publications on VO 2 is explained by the importance of these studies from the viewpoint of possible technical applications (which will be in rather more detail discussed in Section V below), because doping allows the control the transition temperature and other MIT parameters, in particular, the shift of T t toward room temperature -see, for example, [57], [80], [83], [84].…”

Phase evolution of vanadium oxides obtained through temperature programmed calcinations of ammonium vanadate in hydrogen atmosphere and their humidity sensing properties

“…Ammonium meta-vanadate (AMV, NH 4 VO 3 ) has been widely used as a source material for the syntheses of vanadium oxides by various deposition/synthesis techniques, such as chemical precipitation [33,34], thermal annealing [35], spray pyrolysis [36,37], and autoclave hydrothermal treatment [38].…”