A solid-state reaction technique was used to synthesize polycrystalline Na2WO4. Preliminary X-ray studies revealed that the compound has a cubic structure at room temperature. The formation of the compound has been confirmed by X-ray powder diffraction studies and Raman spectroscopy. Electrical and dielectric properties of the compound have been studied using complex impedance spectroscopy in the frequency range 209 Hz–1 MHz and temperature range 586–679 K. The impedance data were modellized by an equivalent circuit consisting of series of a combination of grains and grains boundary. We use complex electrical modulus M* at various temperatures to analyse dielectric data. The modulus plots are characterized by the presence of two relaxation peaks thermally activated. The morphologies and the average particle size of the resultant sodium tungstate sample were demonstrated by atomic force microscopy, scanning electron microscopy and transmission electron microscopy. The thicknesses and optical constants of the sample have been calculated using ellipsometric measurements in the range of 200–22 000 nm by means of new amorphous dispersion formula which is the objective of the present work. The results were obtained for Na2WO4 particles from experimental (EXP) and measured (FIT) data showed an excellent agreement. In addition, the energy gap of the Na2WO4 sample has been determined using ellipsometry and confirmed by spectrophotometry measurements.

Thin films of inorganic materials as Tin-doped indium oxide, titanium oxide, Niobium doped titanium oxide, were deposited for comparison on glass and Polyethylene terephthalate (PET) substrates with a DC sputtering method. These thin films have been characterized by different techniques: Dektak Surface Profilometer, X-ray diffraction (XRD), SEM, (UV/Vis/NIR) spectrophotometer and spectroscopic ellipsometry (SE). The optical parameters of these films such as transmittance, reflectance, refractive index, extinction coefficient, energy gap obtained with different electronic transitions, real and imaginary ( , ) dielectric constants, were determined in the wavelengths range of (200 -2200) nm. The results were compared with SE measurements in the ranges of (0.56-6.19) eV by a new amorphous model with steps of 1 nm. SE measurements of optical constant have been examined and confirm the accuracy of the (UV/Vis/NIR) results. The optical properties indicate an excellent transmittance in the visible range of (400 -800) nm. The average transmittance of films on glass is about (86%, 91%, 85%) for (ITO, TiO 2 , TiO 2 :Nb (NTO)) respectively and decreases to about (85%, 81%, 82%) for PET substrates. For all these materials the optical band gap for direct transition was (3.53, 3.3, 3.6) eV on glass substrates and on PET substrates using two methods (UV and SE). A comparison between optical constants and thickness of these ultrathin films observed gives an excellent agreement with the UV results. The deposited films were also analyzed by XRD and showed an amorphous structure. The structural morphology of these thin films has been investigated and compared.

Graphene oxide (GO) thin films were prepared successfully using modified Hummer’s method, which includes oxidation of graphite and reduction to graphene oxide at room temperature. Then; the samples were deposited on glass substrates using the sol-gel technique. Different solutions have been used to obtain graphene oxide such as Ethanol, Acetone, and Deionized Water. The structural, optical and electrical properties of the prepared samples were diagnosed and studied using optical microscope and XRD diffraction, Fourier Transform Infrared Spectroscopy (FTIR) and UV-Vis spectrophotometer respectively. XRD pattern confirmed the formation of graphene oxide with a sharp peak at an angle of 2θ=11.42°. Thicknesses of (GO) samples using weight method have been calculated. In addition, the optical properties of the samples such as transmittance, reflectance, refractive index, extinction coefficient, and optical energy gap have been measured. The optical band gap of the samples dissolved in acetone, deionized water and ethanol has been measured of about 2.5, 2.45 and 2.35 eV respectively.