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Reduced graphene oxide (rGO) film sensors were fabricated by thermally reduced graphene oxide (GO) at various temperatures. According to the morphological analysis, it was found that rGO synthesized at 200 °C exhibited a crumpled plate-like structure with a much larger surface area within the range of 195.82 m2 g−1, above that of GO. The structural analysis demonstrated the presence of a significant concentration of oxygen functional groups on a typical GO surface, which decreased after the reduction process. Additionally, the peak corresponding to the (001) plane shifted from 13.7° to 25.65° upon increasing the temperature to 200 °C. The rGO films were utilized as a sensor for NH3 gas at varying operational temperatures. The sensitivity, response, and recovery times of the rGO and GO sensors were investigated. The rGO sensor synthesis at 200 °C was found to have a high response of 11% when operated at a working temperature of 200 °C. [ABSTRACT FROM AUTHOR]

In this work, optical properties including absorption coefficient (α), linear refractive index (n) as well as the energy gap (Eg) of crystal violet dye was estimated in two phases. The first phase: when the dye was dissolved in water at different concentrations (1 × 10-1, 1 × 10-2, 1 × 10-3, 1 × 10-4, 1 × 10-5ml). The second phase is the deposition of polyvinyl alcohol for different thicknesses (2, 4, 6, 8 and 10 µm) and with fixed concentration (1 × 10-3 ml) as thin films. It was found that the linear optical properties increased with increasing thicknesses while the energy gap is increasing from 3.9 to around 4.1 eV with increasing CV concentrations resulting from the indirect transitions. [ABSTRACT FROM AUTHOR]

Four-point probe characterization is a standard method for studying the electrical properties of solids and thin films. A simple and cheap four-point probe system has been successfully designed and fabricated using collinear mode. Platinum thin films have been fabricated with different concentrations of Chloroplatinic acid hexahydrate H2PtCl6 on Fluorine-doped tin oxide (FTO) substrate using the spin coating method. The results revealed that the sheet resistances of bare FTO close to the approximated value that was calculated by Sigma Aldrich. Platinum thin films on the FTO substrate lead to a slight change in the surface resistance. [ABSTRACT FROM AUTHOR]

The optical properties of silver nitrates aqueous solution were investigated at different concentrations (1 x10-1, 1 x 10-2, 5 x 10-2 and 1 x 10-3 M). As well thin silver nitrate films of various thickness (210.76, 223.12, 241.56 and 287.87 nm) were prepared via pulse laser deposition (PLD) technique using different laser pulses (250, 200, 150, 100 Pulses). Several optical characterizations were studied such as optical absorption properties, optical energy gap, absorption coefficient, extinction coefficient, index of refraction, reflectivity, transmission, optical conductivity and the real and imaginary electrical insulation constant. The results showed that, as one might expect, the absorption increases with increasing concentration of silver nitrate, while the transmission decreases. Furthermore, it has been observed that there is an increase in the absorption coefficient, extinction coefficient and coefficient of refraction as a function of photon energy with increasing the thickness of thin film, while the transmittance decreases with increasing thickness of the film. Also, the linear optical properties were calculated as a function of photon energy and found to increase with increasing thickness of the film. The optical energy gap was calculated for the allowed direct transfer of thin films different thicknesses and was found to decrease with increasing thickness. [ABSTRACT FROM AUTHOR]

Aluminum Oxide (Al2O3) nanocrystalline have been deposited at varying deposition time of 1h, 2h and 3h on glass substrate via chemical deposition (CD) technique. Morphological, structural and optical properties were obtained to study the influence of the deposition time on the Al2O3 films. The surface morphology and crystallinity show that the particle size decreased from 56.32 nm to 35.89 nm when the deposition time increased from 1h to 3h. Also, the average diameter decreased from 80.78 nm to 71.88 nm with increasing time from 1h to 3h respectively. The optical properties were carried out using UV-Vis spectroscopy measurements and the result indicated that the transmittance spectral decreased when the deposition time increasing. In addition, the energy gap (Eg) decreased from 3.88 to 3.69 eV when the deposition time increasing from 1h and 3h respectively. The results indicated that the optical characterizations depend stronger on the deposition time. [ABSTRACT FROM AUTHOR]