Physics Access

Assessment of Radiological Risks in Sections of Niger Delta University campus, Bayelsa State, Nigeria

2024-07-30T06:42:48+00:00

This paper presents an assessment of background radiation levels within the Niger Delta University campus, Bayelsa State Nigeria. A portable Geiger-Muller tube (Radiation Alert) was used to detect the background ionizing radiation within a temperature range of -100 ℃ to 500 ℃. Results of absorbed dose rate in air in the main campus, open field and new campus vary from 104.4 nGy/h to 278.4 nGy/h with an average of 156.6 nGy/h, 34.8 nGy/h to 174.0 nGy/h with an average of 95.7 nGy/h and 69.6 nGy/h to 174.0 nGy/h with an average of 113.1 nGy/h respectively. The annual effective dose estimates ranged from 0.160 mSv/y to 0.427 mSv/y with an average of 0.024 mSv/y, 0.053 to 0.267 mSv/y with an average of 0.147 mSv/y and 0.107 to 0.267 mSv/y with a mean of 0.173 mSv/y in the main campus, open field and new campus respectively. The excess lifetime cancer risks ranged from 0.442 to 01.174 x 10-3 with a mean of 0.663 x 10^-3, 0.146 to 0.736 x 10^-3 with an average of 0.405 x 10^-3 and 0.295 to 0.736 x 10^-3 with average 0.479 x 10^-3 in main campus, open field and new campus respectively. The estimated averages of absorbed dose rates in the air within Niger Delta University were above the world average of 57 nGy/h. Annual Effective Dose Equivalent (AEDE) are below the safe limit of 1 mSv/y for humans. The results of this study provide baseline information on the background ionizing radiation and can be referenced for future works in the area.

Structural, Electronic, and Optical Properties of Stanene and Stanene-Doped Non-metals for Optoelectronics Applications: A first-principle Study

2024-07-30T06:52:22+00:00

No Abstract

Landslide Susceptibility Assessment in a Basement Environment using Slope and Geoelectric Parameters: Case Study of Adebowale Area, Akure Southwestern Nigeria

2024-07-30T07:06:05+00:00

The assessment of landslide susceptibility was carried out at Adebowale community in Akure South Local Government Area of Ondo State, Nigeria. A total of (60) sixty Vertical Electrical Sounding (VES) data were acquired using Schlumberger electrode configuration with a maximum half-current electrode separation (AB/2) of 150 - 225 m. The Vertical Electrical Sounding (VES) results were presented as maps and tables. The VES results delineated three to five geoelectric layers across the study area. The A, H, K, HA, KH, AKH and HKH are the seven sounding curve types delineated in the area. The resistivity of the topsoil, clayey sand weathered layer, sandy clayey weathered layer and weathered bedrock/fresh bedrock varies from 24 to 961 Ωm, 13 to 4141 Ωm, 24 to 72739 Ωm and 122 to 100000 Ωm respectively. Four parameters of importance to landslide were used to develop a landslide susceptibility model for the study. The parameters consisted of slope, topsoil resistivity, weathered layer resistivity, and longitudinal resistivity. These parameters or factors were assigned weights and ratings based on their significance to the landslide. A landslide susceptibility map (LSSM) was produced using the determined landslide susceptibility index. The LSSM classified the area into five landslide susceptibility zones; very low, low, moderate, high and very high respectively. The model was able to predict areas with very low susceptibility, low susceptibility, moderate susceptibility, high susceptibility and very high susceptibility within the study area. The northern pocket of the southwestern part of the study area revealed very low to low landslide susceptibility while the southwestern and north-central parts of the map are of moderate to very high landslide susceptibility.

Ultra-Thin 2D MoTe₂ for Electron Transport Material Application in Perovskite Solar Cell: A Theoretical Approach

2024-07-30T07:10:37+00:00

With rapid progress in power conversion efficiencies, perovskite solar cells (PSCs) have shown great potential as next-generation low- cost, efficient solar cell devices. Ultra-thin pure and Brdoped MoTe₂ monolayer materials are promising candidates for alternative electron transport material in perovskite solar cell applications. The electronic, and optical properties of these materials were calculated using projector augmented plane wave (PAW) based on popular density-functional theory (DFT). These properties were calculated using Pardew-BurkeErnzerhof generalized gradient approximation (PBE-GGA). The band structure for the considered materials has been determined using full relativistic spin-orbital coupling (SOC). Our results indicate that pure and Br-doped 2D-MoTe₂ were n-type semiconductors and had direct band gap energies of 1.01 and 1.21 eV respectively. The optical properties of the materials such as relative dielectric constant, transmission and reflectivity are presented. Using these properties, the 1-D solar cell capacitance simulator (SCAPS-1D) software was used to design solar cells based on monolayer pure and Br-doped MoTe2 as an electron transport layer (ETL). The maximum efficiencies of these cells are 13.121%, and 24.016% with VOC of 1.067 V and 1.186 V, JSC of 21.678 mA/cm² and 25.251 mA/ cm2 , and FF of 56.720% and 80.139% were realized with the pure and Br-doped ETLs respectively. The performance of our solar cells is comparable to traditional Si-based solar cells. The results show how monolayer pure and Br-doped MoTe₂ can serve as a suitable ETL material for perovskite solar cells.

Development of Heat Conduction Equation using a Heat Propagation Model on ERK Solar Dryer Plates

2024-07-30T07:30:35+00:00

The heat conduction equation is a combination of first-order and second-order differential equations. Solving first-order differential equations is necessary to examine temperature as a function of time. Meanwhile, solving second-order differential equations is needed to examine temperature as a function of space. The heat flux equation is based on Fourier's law, which shows that temperature is a function of time and space. Understanding heat conduction can be improved by building a heat propagation model on the Solar ERK dryer plate. Analysis of heat propagation on the drying plate used the Finite Difference Approach (FDA) method with explicit and implicit schemes. With an explicit scheme, the FDA method calculates the temperature (T) at a point on the spatial derivative term, when T is at time t, while the implicit scheme calculates T at a point on the space derivative term when T is at time t+Δt. Heat propagation at each time change was analyzed by developing a program using the MATLAB 17 application. The results of the analysis show that there are differences in heat propagation between the explicit and implicit schemes. The convergence and stability of calculations in explicit schemes are unstable, causing problems at the time step. Meanwhile, the implicit scheme is carried out simultaneously on all nodes so that convergence and stability are easily maintained, and there are no time-step limitations.

The Effect of Work Function of Back Contact Metals on the Performance of CdTe Solar Cells

2024-07-30T07:34:48+00:00

The CdTe thin film solar cells suffer power losses at the back contact due to charge losses due to poor mismatch of the work function of interfacing back contact materials. Thus, there is a need to find appropriate back contact materials that do not reduce cell performance by creating large Schottky barriers. One of the established strategies employed to reduce the barrier height is depositing metal(s) with high work function to the CdTe back surface. In this study, we used the average of the commonly reported values of the work function of metals, to investigate the effects of various metals, when used as back contacts, on the performance of CdTe solar cells. Without any other strategy employed to overcome the Schottky contacts, the solar cells' efficiency is gravely diminished when metals with work functions lower than 5.0 eV are used. While metals like Pt, Pd, and Au with very high work functions produce cells with efficiencies of up to 18.6%, lower work functions metals like Al almost completely diminished the efficiency to less than 0.5%. our findings indicate that the Schottky barrier affects mainly Voc and FF, as Jsc showed only a slight reduction. When subjected to extreme operating temperatures, the efficiencies largely decreased with temperature. Temperature coefficients of -0.3 to -0.45/oC have been obtained, for the highest- performing metals.

Electrochemically Deposited Iron Sulphide Material by Adjusting the Deposition Time for Photovoltaic Application

2024-07-30T07:38:44+00:00

An electrochemical deposition technique was employed to synthesize FeS material. The Iron nitrate nonahydrate (Fe(NO₃)₂.9H₂O) and sodium sulphate (NaSO₄) are part of the electrochemical bath system. The films synthesized have a polycrystalline structure with diffraction peaks and a preferred orientation along the (111) diffraction plane. The significance of high peaks lies in their ability to provide a spacious surface area for efficient photovoltaic activities. By increasing the deposition time of FeS, the film thickness decreased from 108.98 to 100.87 nm. The FeS absorbance decreases as the wavelength approaches the VIS-IR region. The FeS material had the highest absorbance value at 30 s across the entire spectrum, averaging a maximum of 0.072 in the ultraviolet region. The films deposited had energy band gaps ranging from 2.12 to 1.58 eV. The energy band gap also decreased as the deposition time and film thickness decreased. The bandgap energy range found in this study is perfect for absorbing solar energy radiation above 1.58 eV, making it ideal for solar cell absorber layers.

Investigating the influence of precursor temperature on the bandgap energy, structural, and morphological features of Ti-doped barium sulphide material for photovoltaic application

2024-07-30T07:43:06+00:00

In this study, we use electrochemical deposition on FTO to grow BaTiS thin films. By varying the temperature of the precursors, we conducted thorough growth studies to understand how these process parameters affected the structure of BaTiS films. The diffraction peaks in the XRD pattern match the cubic barium sulfide structural phase. The observed peaks, 39.994 ° and 65.742 ° at 35 °C; 39.982 ° and 65.717 ° at 45 °C, and 39.995 °, 63.920 °, and 65.856 ° at 55 °C. The film deposited at 55 °C had a surface morphology with uniformly distributed spherical-shaped particles that formed agglomerations. The film's surface was smooth, providing a clearer look at the grain boundaries, suggesting a polycrystalline composition. The films deposited at temperatures of 35 °C, 40 °C, 45 °C, 50 °C, and 55 °C yielded energy band gaps of 2.98 eV, 2.90 eV, 2.69 eV, 2.68 eV, and 2.30 eV, respectively. The result showed that the films' energy band gap decreased as the deposition temperature increased. The varied energy bandgap of the films confirmed the effects of deposition temperature on the films.

Assessment of Radon Concentration in Groundwater with Associated Human-Health Implications around Bagwai and Shanono Artisan Gold Mining Site Kano State, Northwestern Nigeria

2024-07-30T07:50:01+00:00

This study assesses the activity concentration of Radon in underground water around Bagwai and Shanono artisan gold mining Sites in Kano State, Northwestern Nigeria. A total of (39) underground water samples, including sixteen (16) from boreholes and twenty-three (23) from hand-dug wells, were randomly collected. The activity concentration of Radon was analyzed using a portable radon detector, Rad7, from DURRIDGE Company. The results show that the radon concentration in all the water samples ranges from 4.13 to 45.24 Bq/l, with an average value of 20.13 Bq/l. The calculated total annual effective dose due to both ingestion and inhalation for different age groups ranges from 42.40, 57.60 and 65.30 (µSv/y) to 457.10, 622.06 and 704.60 (µSv/y), with an average value of 203.32, 276.70 and 313.51 (µSv/y) for adults, children, and infants respectively. The total excess lifetime cancer risk for different age groups varies from 0.00149, 0.00202 and 0.0247 to 0.0160, 0.0220 and 0.0247 with mean values of 0.00703, 0.00956 and 0.0109 for adults, children, and infants. The obtained results are higher than the internationally recommended limits set by USEPA of 4 to 40Bq/l and the International Commission on Radiological Protection (ICRP) value of 0.1mS/y; thus, the water in the study area is not suitable for drinking and other domestic purposes. Hence, remedial action needs to be taken by the authorities to ensure the continuous utilization of water within the study area.