Hydrothermal synthesis and characterization of undoped and W-doped vanadium dioxide nanorods for thermochromic application

•Undoped and W-doped VO2 nanorods were synthesized by a two-step hydrothermal method.•VO2(M) nanorods were synthesized from V2O5 and oxalic acid at 220°C post-annealing.•The XRD pattern of the (011) peak shifts to a small angle when W-doping increases.•The length and width of the rods ranged from 35...

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Bibliographic Details
Published in:Journal of crystal growth 2022-07, Vol.590, p.126702, Article 126702
Main Authors: Numan, N., Madiba, I.G., Khanyile, B.S., Khumalo, Z.M., Maaza, M.
Format: Article
Language:English
Subjects:
A1. Doping with Tungsten
A1. Phase transition temperature
A2. Hydrothermal synthesis
Angle of reflection
B1. Nanostructured materials
B1. Vanadium dioxide ([formula omitted])
Diffraction patterns
Electron microscopes
Hydrothermal reactions
Nanorods
Oxalic acid
Room temperature
Scanning electron microscopy
Vanadium dioxide
Vanadium oxides
Vanadium pentoxide
X-ray diffraction
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Summary:•Undoped and W-doped VO2 nanorods were synthesized by a two-step hydrothermal method.•VO2(M) nanorods were synthesized from V2O5 and oxalic acid at 220°C post-annealing.•The XRD pattern of the (011) peak shifts to a small angle when W-doping increases.•The length and width of the rods ranged from 356–790 nm, and 51–217 nm respectively. Owing to vanadium dioxide’s semiconductor to metal transition near room temperature, it is an ideal candidate for thermochromic applications. In this paper, we report the synthesis of undoped and W-doped vanadium dioxide (VO2) nanorods using hydrothermal method. VO2 (B) was synthesized via a hydrothermal reaction from vanadium pentoxide (V2O5) and oxalic acid dihydrate (H2C2O4·2H2O). VO2 (B) transformed to VO2 (M) after annealing at 500°C under vacuum. The structure and morphology of the synthesised nanorods were investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM), differential scanning calorimetry (DSC) and transmission electron microscopy (TEM). For the (011) peak, the XRD patterns of undoped VO2 nanorods powder showed a highly crystalline pure monoclinic phase. The X-ray diffraction patterns of the samples show a decrease in the intensity and shift slightly toward the direction of the small reflection angle when increasing W-content. According to the SEM results, the nanorods produced have length ranging from 356 to 790 nm, and the width ranges from 51 to 217 nm.
ISSN:0022-0248
1873-5002
DOI:10.1016/j.jcrysgro.2022.126702