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<p>Urchin-like W-doped VO<sub>2</sub>:Au nanocomposites are prepared using hydrothermal synthesis route and thermal annealing. Prepared W-doped VO<sub>2</sub> is mixed with HAuCl<sub>4</sub> in weight ratio of 1:1, 5:1 and 10:1 to make nanocomposites. The mixture is then annealed at 300&#xa0;°C in the presence of argon. Surface morphology of pristine VO<sub>2</sub>, W-doped VO<sub>2</sub>, and composite samples are studied using scanning electron microscope (SEM) that reveals fibrous structure of pristine VO<sub>2</sub>, and urchin-like structure of W-doped VO<sub>2</sub>. All the composites also show urchin-like structure. Structural analysis using X-ray diffraction (XRD) spectroscopy shows existence of mixed polymorphs (VO<sub>2</sub> (B), VO<sub>2</sub> (M) and VO<sub>2</sub> (A)) in pristine VO<sub>2</sub>, W-doped VO<sub>2</sub> and composites. While doping may cause lattice expansion due to replacement of V<sup>4+</sup> by W<sup>4+</sup> or W at interstitial position, the presence of Au in the composites leads to co-existence of possible rutile phase along with dominating VO<sub>2</sub> (B) and VO<sub>2</sub>(M) phases. The VO<sub>2</sub> (B) phase transforms to VO<sub>2</sub> (M) with increasing W-doping concentration. Raman spectroscopic studies further confirm co-existence of VO<sub>2</sub> polymorphs. Presence of Au in the composites broadens the Raman peaks which is attributed to the local near-field and heating effects caused by the Raman excitation beam. Temperature&#xa0;dependent electrical resistive response shows 3-5&#xa0;times resistance modulation within a temperature change of ± 5&#xa0;°C about T<sub>c</sub>. Furthermore, temperature&#xa0;dependent optical reflection shows about 10-20% modulation in the visible to near-infrared (450-1000&#xa0;nm). These observations indicate thermal switchability of electrical and optical signal.</p>

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Structural, Electrical and Optical Properties of Switchable W-Doped VO2: Au Urchin-Like Composite Nanomaterials Prepared by Hydrothermal Route and Thermal Annealing

  • 期刊论文

  • 发表日期：

    2026年2月13日

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  • Shraddha Shukla,
  • Abhishek Prasad,
  • P. Mandal

摘要

Urchin-like W-doped VO2:Au nanocomposites are prepared using hydrothermal synthesis route and thermal annealing. Prepared W-doped VO2 is mixed with HAuCl4 in weight ratio of 1:1, 5:1 and 10:1 to make nanocomposites. The mixture is then annealed at 300 °C in the presence of argon. Surface morphology of pristine VO2, W-doped VO2, and composite samples are studied using scanning electron microscope (SEM) that reveals fibrous structure of pristine VO2, and urchin-like structure of W-doped VO2. All the composites also show urchin-like structure. Structural analysis using X-ray diffraction (XRD) spectroscopy shows existence of mixed polymorphs (VO2 (B), VO2 (M) and VO2 (A)) in pristine VO2, W-doped VO2 and composites. While doping may cause lattice expansion due to replacement of V4+ by W4+ or W at interstitial position, the presence of Au in the composites leads to co-existence of possible rutile phase along with dominating VO2 (B) and VO2(M) phases. The VO2 (B) phase transforms to VO2 (M) with increasing W-doping concentration. Raman spectroscopic studies further confirm co-existence of VO2 polymorphs. Presence of Au in the composites broadens the Raman peaks which is attributed to the local near-field and heating effects caused by the Raman excitation beam. Temperature dependent electrical resistive response shows 3-5 times resistance modulation within a temperature change of ± 5 °C about Tc. Furthermore, temperature dependent optical reflection shows about 10-20% modulation in the visible to near-infrared (450-1000 nm). These observations indicate thermal switchability of electrical and optical signal.