In this study we tested the effect of annealing time on some properties of titanium dioxide thin films, elaborated by the chemical technique spray pyrolysis deposited on the glass with a fixed ...temperature. An annealing was carried out at a temperature of 500 °C for three times 1 h, 2 h and 3 h. The structural characterization with X-ray diffraction (XRD) shows a significant increase in the crystallite size and also the preferential peak intensity of TiO2 of the anatase phase if the annealing time is decreased, the typical Scanning Electron Microscopy (SEM) image shows the morphological properties of TiO2 thin film and the optical measurement with UV–Visible spectrophotometer represent the semiconductor properties of TiO2 with an optical band gap that varies with the variation of the annealing time from 3.30 to 3.26 eV for 3 h to 2 h and from 3.26 to 3.19 eV for 2 h to 1 h.
Insufficient data on the chemical composition of PMsub.2.5 and its emission sources in the southwestern (SW) Mediterranean area has been identified. Ambient PMsub.2.5 samples were collected in an ...urban area of Tetouan city, northern Morocco. Chemical mass closure calculations and positive matrix factorization were performed for the comprehensive dataset of PMsub.2.5 chemical analyses. Mass closure improved when multipliers (1.2 and 0.23, respectively) were used for the conversion of organic carbon (OC) and calcium ion (Casup.2+ ) into particulate organic matter (POM) and mineral dust masses, respectively. The mass closure model performed well in this SW Mediterranean region, with a significant correlation (rsup.2 = 0.97) obtained between gravimetrically measured and chemically determined PMsub.2.5 mass. The one-year average concentration of PMsub.2.5 was 17.96 μg/msup.3 , and the major chemical components were POM (34%), secondary inorganic aerosol (SIA) (28%), and black carbon (18%), while unidentified mass was 4%. The mass concentration and most of the chemical components of PMsub.2.5 showed clear seasonal variations, with a summer-high and winter-low pattern for SIA, dust, and BC. In the winter months, POM was the dominant component. Source apportionment analysis revealed that PMsub.2.5 emission sources, regarding their typical tracers, were ammonium sulfate (SOsub.4 sup.2− , NHsub.4 sup.+ , Ksup.+ , NOsub.3 sup.− ), road traffic and biomass burning emissions (OC, BC), fresh sea salt (Clsup.− , Ksup.+ , NOsub.3 sup.− ), aged sea salt (Mgsup.2+ , Nasup.+ , Casup.2+ ), and oxalate-rich (oxalate, NOsub.3 sup.− ) factors. Further, it is hoped that these findings help to improve the scientific understanding of SW Mediterranean aerosols.
In this work, we synthesis the SnO2 thin layers by low-cost spray pyrolysis, the thin layers were analyzed using X-ray diffraction, Raman spectroscopy, Scanning electron microscopy (SEM), and ...UV–Visible spectrophotometer. The structural studies showed that SnO2 thin layers are of Rutile phase with strong preferred direction along (1 1 0) plan. The SEM image showed that SnO2 thin layers have a roughness and porous surfaces, which proved that SnO2 layers are suitable for gas sensor applications. The energy band gap (Eg) has been calculated from the transmittance curve and certified the semiconducting properties with a Eg = 3.65 eV. The Ab-initio method was applied based on the density functional theory (DFT) using the Wien2K code. The generalized gradient approximation and MBJ potential method have been utilized to determine the band structure, density of states, and optical properties of tin dioxide material. Our theoretical results are in good agreement with the obtained practically.
In this work we prepared and deposited Cu2ZnSnS4 (CZTS) absorber layers by sol gel spin coating technique on ordinary glass substrates. We studied the influence of annealing time on structural, ...compositional, morphological, optical and electrical properties of films at different times of 5, 10 and 20 min, respectively. The films have been analyzed by different characterization techniques such as X-ray diffractometer (XRD), Raman spectroscopy, scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), UV–visible-NIR spectrophotometer and four point probe method. XRD patterns showed pure kesterite CZTS with preferential orientation along (112) plane and calculated lattice parameters a = b = 0.5428 nm and c = 1.0849 nm. Raman scattering measurements confirmed the existence of a single CZTS phase showing a single peak at 338 cm−1. SEM images showed compact, uniform and densely surface morphology. EDS analysis indicated near-stoichiometric CZTS films, UV–Visible-NIR spectrophotometer showed that the optical band gap energy of CZTS thin films is found to be between 1.48 and 1.7 eV. Four point probe measurements exhibited a suitable electrical conductivity in the range 3.03–3.44 (Ω.cm)−1. These properties make the as-synthesized CZTS films an appropriate material as absorber layer in solar cells applications.
ITO thin layers were deposited with good results on a glass substrate by Spray pyrolysis method under optimal conditions using the TAGUCHI experimental design. Structural, optical and electrical ...characteristics have been studied and evaluated via X-ray diffraction, UV–visible spectrophotometry and the 4-point probe method. On the optical analysis by taking measurements of average transmittance T (λ) and absorption A (λ) over the wavelength interval from 300 to 1000 nm, the indirect band gap energy can be determined. The analysis of our ITO thin films shows that the confirmatory test has the best performance. The ideal preparation conditions of ITO thin films were the following: surface temperature is 450 °C, the ratio of indium and tin was 10%, as well as the deposition time was 10 min. The mean optical transmittance in visual range and sheet resistance of ITO film were 85% and 22.38 Ω/□, respectively.
Indium doped Titanium dioxide (TiO2: In) thin layers were deposited on glass substrates by the spray pyrolysis deposition with the substrate temperature 450 °C. The structural and the optical ...properties studies were investigated for the films deposited with various atomic doping indium percentage (0, 1, 3, 5 and 7 at.%). The results of X-ray diffraction (XRD) was shown the presence of anatase peak with a strong orientation along (1 0 1) plane. The crystallite size was found to be between 7.09 and 14.43 nm. Raman spectroscopy of undoped and doped TiO2 thin films were confirmed the presence of single phase of anatase TiO2. The optical properties were determined using absorbance and transmittance results in the range of wavelength between 300 and 800 nm. The calculated optical band gap varied between 3.08 and 3.25 eV. The Hall measurement displayed an increase of conductivity 1.04 to 5.03 Ω−1.cm−1 and the electron mobility from 11.33 to 35.70 cm2/V.s in front of the decrease of the resistivity from 9.56 × 10−1 to 1.98 × 10−1 Ω.cm for the variation of atomic doping from 0% to 7%. The best obtained properties of undoped and doped TiO2 make our sprayed thin films suitable to be as sensitive layer for optoelectronic applications among these, a gas sensor application.
The Nador lagoon is a coastal wetland which is subject to both the watershed pressures and land runoffs coming from domestic, agricultural, industrial and mining pollution. In 2017, 19 stations ...encompassing the entire lagoon and pollution sources, including 13 at the lagoon level and 6 at the watershed level, were sampled during wet and dry seasons. Descriptive and multivariate statistical analyses were used to assess its environmental status through physio-chemical, nutrients and trace metals parameters. The results show that seasonal variations significantly affected the concentrations of Fe, Cu, Cr, and Cd in the lagoon. The highest mean concentrations were recorded for Mn, Zn, Cr and Pb during the wet season and for Fe, Cu, Ni and Cd during the dry season. The average concentrations of Pb, Cd, Cr, Zn and Mn in the lagoon were lower than the USEPA 2016 standards on saltwater aquatic life preservation while the average concentrations of Ni and Cu are higher. In order to preserve this wetland, the implementation of an environmental management plan is required focusing on the rehabilitation of the iron mining area, the extension of the sewerage network, the control of agricultural effluents and the upgrading of industrial pollution controls.
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