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<p>This work focuses on the synthesis of cobalt tungstate (CoWO<sub>4</sub>) nanoparticles by a chemical precipitation process. Different concentrations (0.0, 0.02, 0.04, 0.08, and 0.16 wt.%) of CoWO<sub>4</sub> nanoparticles were doped into the PVA/PVP polymer blend using the casting method. X-ray diffraction (XRD) confirmed the presence of peaks corresponding to cobalt and tungsten with the monoclinic unit cell of PVA. The estimated crystallite size of pure CoWO<sub>4</sub> nanoparticles ≈ 44&#xa0;nm. UV–visible spectroscopic measurements demonstrated that the incorporation of CoWO<sub>4</sub> nanoparticles resulted in a reduction in bandgap energy from 5.18 to 3.43&#xa0;eV for direct allowed transitions and from 5.22 to 3.88&#xa0;eV for direct forbidden transitions. Also, the optical parameters were studied in detail. SEM images of CoWO<sub>4</sub> nanoparticles show a highly porous and agglomerated microstructure with irregular shapes and rough surfaces, a typical feature of conventional synthesis methods. EDX confirms the presence of Co, W, and O, consistent with the successful synthesis. The electrical modulus (M′) exhibited a frequency-dependent increase, indicating enhanced short-range charge carrier mobility. M″ displayed a dipolar relaxation peak at grain boundaries, shifting to higher frequencies with CoWO₄ incorporation- evidence of nanoparticle-induced polymer matrix reorganization. Nyquist plots revealed expanding semicircle diameters at higher CoWO<sub>4</sub> concentrations, reflecting improved charge transport due to optimized nanoparticle dispersion within the PVA/PVP nanocomposite.</p>

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Investigation of the structural and multi-functional properties of PVA/PVP-CoWO4 nanocomposite films

  • 期刊论文

  • 发表日期：

    2025年6月30日

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  • Nuha Al-Harbi,
  • Lamiaa G. Alharbe

摘要

This work focuses on the synthesis of cobalt tungstate (CoWO4) nanoparticles by a chemical precipitation process. Different concentrations (0.0, 0.02, 0.04, 0.08, and 0.16 wt.%) of CoWO4 nanoparticles were doped into the PVA/PVP polymer blend using the casting method. X-ray diffraction (XRD) confirmed the presence of peaks corresponding to cobalt and tungsten with the monoclinic unit cell of PVA. The estimated crystallite size of pure CoWO4 nanoparticles ≈ 44 nm. UV–visible spectroscopic measurements demonstrated that the incorporation of CoWO4 nanoparticles resulted in a reduction in bandgap energy from 5.18 to 3.43 eV for direct allowed transitions and from 5.22 to 3.88 eV for direct forbidden transitions. Also, the optical parameters were studied in detail. SEM images of CoWO4 nanoparticles show a highly porous and agglomerated microstructure with irregular shapes and rough surfaces, a typical feature of conventional synthesis methods. EDX confirms the presence of Co, W, and O, consistent with the successful synthesis. The electrical modulus (M′) exhibited a frequency-dependent increase, indicating enhanced short-range charge carrier mobility. M″ displayed a dipolar relaxation peak at grain boundaries, shifting to higher frequencies with CoWO₄ incorporation- evidence of nanoparticle-induced polymer matrix reorganization. Nyquist plots revealed expanding semicircle diameters at higher CoWO4 concentrations, reflecting improved charge transport due to optimized nanoparticle dispersion within the PVA/PVP nanocomposite.