A.M. El Sayed

Influence of Cr2O3 nanoparticles on the physical properties of polyvinyl alcohol

Nano-sized chromium oxide (Cr2O3) was synthesized by sol-gel method and mixed with polyvinyl alcohol (PVA) to produce nanocomposite films. Scanning electron microscopy (SEM) was used to observe the morphology and dispersion of Cr2O3 on the surface of the PVA films. X-ray diffraction (XRD) was performed on nano-sized Cr2O3, pure PVA, and Cr2O3/PVA composites. Based on the results of both XRD and high-resolution transmission electron microscopy (HR-TEM), the average particle size of the Cr2O3 was ≈ 46 nm. Differential scanning calorimetry (DSC) showed that the thermal stability and degree of crystallinity of the PVA were reinforced by the addition of Cr2O3 nanoparticles. The absorbance and extinction coefficients of the composites were studied in the UV-vis range and compared with those of pure PVA. The optical energy band gap, Eg, was calculated. Dielectric constant, e′, dielectric loss modulus, M″, and ac conductivity, σac, of all samples were measured within temperature and frequency ranges of 300–468 K ...

Structural, optical and photocatalytic properties of Fe and (Co, Fe) co-doped copper oxide spin coated films.

Copper oxide films with composition Cu1-x-yFexCoyO (where x⩽0.06 and y⩽0.03 in a molar ratio) and thickness of about 2 μm were spin coated onto ultrasonically cleaned glass substrates. These films were annealed at 500 °C in the air. XRD results show that films are CuO of polycrystalline and monoclinic structures without the detection of any Fe or Co traces. The average crystallite size of pure CuO is 20.44 nm reduced to 18.72 nm after Fe doping, then increased to 26.82 nm due to the co-doping with Co atoms. The optical band gap blue-shifted from 2.15 eV to 2.3 eV followed by red-shift to 2.15 eV after the Co incorporation. The influence of Fe doping and Co co-doping on the optical constants of CuO films as well as the photocatalytic removal of methylene blue (MB) dye is reported. The correlations between the structural modifications and the resultant optical properties are discussed. The obtained results of the fabricated system are compared with those of similar materials.

Synthesis, structural and optical properties of tin oxide nanoparticles and its CMC/PEG–PVA nanocomposite films

Polyethylene glycol–polyvinyl alcohol (PEG–PVA) blend is a multifunctional material and controlling its properties is important for various medical and industrial uses. In this paper, we report the influence of carboxymethyl cellulose (CMC) and doping with tin oxide (SnO2) nanoparticles (NPs) on the structural and optical properties of PEG–PVA. The prepared samples were investigated by X-ray diffraction (XRD), high-resolution transmission electron microscopy (HR-TEM), scanning electron microscopy (SEM), Fourier transform infrared (FTIR) and UV–Vis-NIR spectroscopies. SnO2 NPs of rutile structure, average crystallite size of ∼30.2 nm and optical band gap (Eg) of 3.68 eV were prepared by a simple sol–gel process. CMC addition enhances the crystallinity of PEG–PVA that then gradually reduced by increasing SnO2 doping ratio. The optical transmittance of PEG–PVA increased from 77 to 90% after mixing with CMC and then decreased to 64% with increasing SnO2 content to 1.5%. Also, the Eg of PEG–PVA increased from 5.20 to 5.28 eV and then decreased to 4.88 eV due to CMC addition and SnO2 incorporation, respectively. The refractive index, the dispersion parameters and the optical conductivity of PEG–PVA, CMC/PEG–PVA and of its nanocomposite films are discussed. The correlation between the structural modifications and the resultant optical properties are reported.