Investigation of the Temperature on the Thin Layers of Cobalt Oxide Produced by the Spray Pyrolysis Method Using a Solar Oven

Thin films of cobalt oxide (Co3O4) were prepared on glass substrates by the spray pyrolysis method using a solar concentrator (oven) manufactured in our laboratory. We used different processing temperatures (300° C, 350° C and 400° C). The structural, optical and electrical properties of the different samples were analyzed by X-ray diffraction (XRD), UV-Visible spectroscopy and the Hall effect measurement system. X-ray diffraction observations revealed that cubic crystals are created in all films produced, and the film structure is that of a single phase created with preferential orientation along the (311) axis in films at low temperatures, and the axis (111) for high temperatures. The grain sizes of our products vary between (22.62nm and 66.19nm), depending on the processing temperature. The optical band gap of the crystals obtained was measured. The results of the optical forbidden bands of the crystals obtained, indicated two bands of the values for each element (Eg1 and Eg2). We observed that the values of the effective optical forbidden bands increase by 2.547eV and 3.0731eV with the increase in the production temperature., In addition the film produced experiences a decrease in the Urbach parameters which vary between 162.20meV and 360.81meV depending on the increase in production temperatures. Finally, the films produced have electrical conductivity values of (1.090 [(Ω.cm)−1] to 1.853 [(Ω.cm)−1] and electrical resistivity values of 1.431 (Ω.cm) at 1.853 (Ω.cm), depending on the variation in the production temperature.

Spectral Characteristics of Solar Radiation in Timisoara, Romania

This study deals with the spectral distribution of solar radiation in Timisoara, Romania. Solar spectrum at the ground level was estimated based on Leckner’s spectral solar irradiance model and measured atmospheric parameters over the years 2019-2020. The average photon energy index (APE) was used to capture the characteristic signature of the solar radiation spectrum. The results emphasize considerable differences between the solar radiation spectrum in Timisoara and the standard AM1.5G spectrum. During 2019-2020, APE has taken values between 1.841 eV and 1.929 eV, indicating both red- and blue-shift from the standard AM1.5G spectrum. To our best knowledge this is the first study which discusses the signature of solar radiation spectrum in terms of APE for a location in Romania.

Scattering of Fermions by a Magnetic Dipole Field

In this paper we study the problem of fermions scattering by the field of a magnetic dipole in Minkowski space-time. The amplitude and differential cross section for scattering of massive fermions are obtained using the exact solution of the Dirac equation written in the helicity basis. We found that the most probable transitions are those that scatter the fermions perpendicular to the direction of the magnetic field and we consider only the transverse momenta in our analysis. The differential cross section behavior in terms of scattering angle and energy is graphically analysed and we perform a comparative study with the Coulomb scattering.

Correlation of Rheological Properties of Ferrofluid-Based Magnetorheological Fluids Using Some Dimensionless Numbers Defined in Magnetorheology

In this paper we investigated from rheological point of view some samples of ferrofluid-based magnetorheological fluids (FF-MRFs) with different volumic fractions of Fe microparticles, but with the same ferrofluid used as carrier liquid. We correlated the dimensionless flow curves, measured at different values of the magnetic field induction, using either Mason number or Casson number. It has been shown that in this approach, data sets measured under different conditions collapse on a single curve. This master curve is useful for controlling the concentration of Fe particles, so that the magnetic and magnetorheological properties of FF-MRF to be adapted to obtain high-performance applications.

Structural, Electronic and Optical Properties of ScxGa1-xP Alloys An: Ab Initio Study

The structural, electronic and optical properties of the of ScxGa1-xP alloys have been investigated by using the full-potential plane-wave FP-LAPW method as implemented in the Wien2k code. The exchange-correlation (XC) energy of electrons was treated using the Perdewe-Burke-Ernzerhof parametrization (PBEGGA), and the Tran-Blaha modified Beck-Johnson potential (TB–mBJ). The lattice constant and the bulk modulus have been calculated and analyzed where a deviation from Végard’s law is observed for both. The calculation of the band structure of binary GaP shows that there is an indirect gap of 2.27 eV, while for the ScxGa1-xP compounds there are direct gaps with values of 1.91 eV, 1, 39 eV, 2.04 eV and 1.849 eV for x = 0.25, 0.5, 0, 75 and 1, respectively. At ambient pressure, the refractive index and the dielectric constant are in good agreement with the experimental results. The extinction coefficient does not begin to increase until a threshold, which represents the optical gap. This threshold is equal to 1.224 eV and it starts to increase to reach a maximum at an energy of 3.551 eV.

Geo-Electrical Method of Assessment of Coefficient of Permeability and Porosity of Soil of a Poultry Farmland

Leachate collected at the bottom of dead bird’s disposal pits may leak and migrate to pollute groundwater when soils and rocks present are porous. This study assessed the coefficient of permeability (K) and porosity (Ф) of soils and rocks in poultry farmland using 2 Dimensional (2D) electrical resistivity method and soil analysis. Geo-electrical data collection was achieved by using the dipole-dipole array. The field resistivity measurement was carried out along three traverse lines (three Profiles) of 100 m long which were oriented along with East-West directions. These measurements were taken in the order of increasing in offset distance interval of 5 m. The acquired apparent resistivity data were inverted using DIPPROWIN modeling software to perform 2D data inversion. Five soil samples from different locations at depths of 0 – 15 cm and 15 – 30 cm, on the poultry farmland, were collected, transported, and tested in the laboratory. K and Ф were determined using falling head and density methods respectively. The results obtained from the processed field resistivity data from the three profiles were presented as field data pseudo-sections, theoretical pseudo-section, and 2D resistivity structures. The 2D resistivity structure revealed three structures viz; highly conductive, slightly conductive, and resistive. The resistivity values of these structures ranged from 14.1-99.0 Ω m, 100-848 Ω m, and 1350-90330 Ω m respectively. The highly conductive structures were found in profiles 1 and 3 due to the downward migration of the contaminants from the dead bird disposal pit 1 and the feces disposal site through clayey sand soil. This occurs at the depth range of few meters from the surface to greater than 20 m. The presence of the slightly conductive structure is a result of filtration of the contaminants by the soil materials which increased the resistivity of the soil. The movement of the contaminant through the soil is an indication of the porous and permeable nature of the farmland. The resistive structure is only noticeable in profiles 1 and 2 but very prominent at the depth range of 5 m to more than 20 m and 5 m to 35 m along the profile length. The results of the analysis of the five soil samples from the poultry farmland showed a high value of 0.552 and 3.554 x 10−2cm/s of porosity (Ф) and coefficient of permeability (K) respectively. A strong correlation of R 2 = 0.9878 existed between Ф and K. With these results geo-electrical method had successfully assessed Ф and K of the soil of the poultry farmland.

Ag Continuous Doped SnO2 Sensor Selective to Co2 in Presence of Ethanol at Room Temperature

This paper contains experimental research to minimize the basic limits of the SnO2 semiconductor oxide gas sensor. The operating temperature is high. In addition, their selectivity diminishes with gasses having the same chemical behavior. An experimental methodology is presented to overcome the difficulties of these metal oxides. The efficiency of the gas sensors made of Ag continuously doped at room temperature is excellent. At the end of the testing processes and security measures supplied, laboratory tests and experiments will be conducted to guarantee the acceptability of the planned study.

First-Principles Calculations of the Structural, Electronic and Optical Properties of Yttrium-Doped SnO2

We use FP-LAPW method to study structural, electronic, and optical properties of the pure and Y-doped SnO2. The results show that by Y doping of SnO2 the band gaps are broadened, and still direct at Γ-point. For pure SnO2 material, the obtained values of the direct band gap are 0.607 eV for GGA-PBE and 2.524 eV for GGATB-mBJ, respectively. This later is in good agreement with the experimental data and other theoretical results. The Fermi level shifts into the valence band and exhibits p-type semiconductor character owing mainly from the orbital 4d-Y. Additionally, the calculated optical properties reveal that all concentrations are characterized by low reflectivity and absorption via wavelength λ (nm) in the visible light and near-infrared (NIR) ranges, which leads to a redshift in the optical transparency.

Structural, Chemical and Optical Properties of Pure and Al-Doped Zno Thin Films Derived by Sol–Gel Dip Coating Process

Pure and Al-doped ZnO thin films were successfully deposited with sol-gel dip coating on both substrates Si (100) and glass. The structural, chemical, morphological and optical properties as a function of the annealing temperature and dopant atomic concentration were investigated by means of X-ray diffraction, Energy dispersive X-ray, Scanning Electron Microscopy, and spectrophotometry. All the pure and doped films show a polycrystalline nature and hexagonal in structure. Accurate doping was proven by EDX. In addition, the SEM analysis revealed that the films possess uniform distribution throughout the surface and the grain dimension decreases with Al doping. From the transmittance measurements, it is see that all films are over 55% in the visible region and the band gap energy increases from 3.28 to 3.45 eV with the increase of Al concentration.