Physics and Material Science

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A DFT study of optoelectronic, elastic and thermo-electric properties of the double perovskites Rb2SeX6 (X Br,Cl)
(Journal of the Nigerian Society of Physical Sciences, 2023-04-29) Yahya, W. A.
Thermo-electric (TE) material applications reduce reliance on traditional energy resources by converting heat to electric energy. We have stud- ied, for the first time, the thermo-electric properties of Rb 2 SeX 6 (X Br,Cl). Using norm-conserving pseudo potentials in a plane wave basis set of Quantum Espresso code, the optoelectronic, elastic and thermo-electric properties of Rb 2 SeX 6 (X Br,Cl) have been investigated using den- sity functional theory. Generalized Gradient Approximation of Perdew Burke Ernzerhof (GGA-PBE) and Generalized Gradient Approximation of Perdew Burke Ernzerhof adapted for Solid (GGA-PBESol) exchange correlation functionals were employed in all calculations. The band structure plots suggest that the studied double perovskites have indirect band gaps. Rb 2 SeBr 6 band gap values of 1.7574/ 1.569 eV (using GGA- PBE/PBEsol) are remarkably similar to that of two effective inorganic/organic perovskites FAPbI 3 and MAPbI 3 . Maximum peaks generated from refractive index results indicate possible solar cell uses of the materials because they are in the visible and ultraviolet ranges. The results of other optical properties such as absorption coefficients, electron energy loss, conductivity, and reflectivity concludes that Rb 2 SeX 6 (X Br,Cl) have good values for electron generation, high potential for applications in the optoelectronic industry and are semiconductor in nature. The calculated shear anisotropy values of Rb 2 SeBr 6 /Cl 6 are 3.09/1.71, suggesting that they are isotropic materials. With calculated Poisson’s ratio of 0.32 and 0.26, the materials are predicted to be ductile in nature. The two materials are appropriate for thermo-electric applications since their thermal to electrical conductivity ratio are small (the order of 10 −5 ). The calculated minimum values of Seebeck coefficient values of 0.198 × 10 3 / 0.166 × 10 3 (m V/K) at 750 K, for Rb 2 SeBr 6 /Cl 6 are positive, indicating that they have p-type conduction. Figure of merit values at all temperature range considered are greater than one (ZT > 1) for both Rb 2 SeBr 6 and Rb 2 SeCl 6 , suggesting that they are good thermo-electric materials. The results of the calculations provide the basis for the industrial application of Rb 2 SeBr 6 /Cl 6 as solar cells.
Ab initio Studies of the Structural, Electronic and Mechanical Properties of Zn1−xCrxTe
(2021-02) A. A. Audu; W. A. Yahya; A. A. Abdulkareem
Ab Initio Study of the Physical Properties of Cs-Based Double Perovskites Cs2 AX6 (A = Ge, Mn; X = Cl, I)
(2024-04-15) A.A. Yahaya; W.A. Yahya; A.S. Ahmed; A.A. Sholagberu
Device applications in magnetic media, spintronics, oxygen membranes, sensors, etc., are some of the uses of ferrite materials. In this work, we have studied the structural, electronic, magnetic, mechanical, and thermoelectric properties of Cs-based double perovskites Cs2 AX6 (A = Ge, Mn; X = Cl, I), using Quantum Espresso with generalized gradient approximation Perdew–Burke–Ernzerhof and Perdew– Burke–Ernzerhof in solids exchange–correlation functionals. The band structure results show that Cs2 GeCl6 and Cs2 MnCl6 are semiconductors with direct band gaps. However, there are bands crossing observed for Cs2 GeI6 from the conduction band minimum to the valence band maximum, indicating the metallic nature of the material. Moreover, Cs2 MnI6 has magnetic properties; it exhibits a metal- lic nature in the spin-up state and a semiconductor nature in the spin-down state, suggesting that it can be used in spintronics applications. The calculated total magnetic moment of Cs2 MnCl6 is 3.0µB (for both Perdew–Burke–Ernzerhof and Perdew–Burke–Ernzerhof in solids), while for Cs2 MnI6 , the calculated total magnetic moments are 3.02µB and 3.06µB , for Perdew–Burke–Ernzerhof and Perdew– Burke–Ernzerhof in solids exchange–correlation functionals, respectively. The results of the mechanical properties calculations show that Cs-based double perovskites Cs2 AX6 (A = Ge, Mn; X = Cl, I) are mechanically stable. Cauchy’s pressure and Poisson’s, Frantsevich’s, and Pugh’s ratios of the studied materials confirm that Cs2 MnCl6 is brittle, while the remaining studied double perovskite materials are ductile. Electrical conductivity, thermal conductivity, Seebeck coefficients, power factor, and figure of merit are the thermoelectric parameters analyzed in this study. Seebeck coefficients, electrical con- ductivity, and power factor increase with the rise in temperature, and Cs2 MnX6 (X = Cl, I) double perovskite materials have higher values of electrical conductivity than Cs2 GeX6 (X = Cl, I). All the studied materials have positive type conductivity due to their positive Seebeck coefficient values.
Alpha decay half-lives of 171-189Hg isotopes using Modified Gamow-like model and temperature dependent proximity potential
(2020-11) W. A. Yahya
The alpha decay half-lives for $^{171-189}\mathrm{Hg}$ isotopes have been computed using the Gamow-like model (GLM), modified Gamow-like model (MGLM1), temperature-independent Coulomb and proximity potential model (CPPM), and temperature-dependent Coulomb and proximity potential model (CPPMT). New variable parameter sets were numerically calculated for the $^{171-189}\mathrm{Hg}$ using the modified Gamow-like model (termed MGLM2). The results of the computed standard deviation indicates that the modified Gamow-like model (MGLM2) and the temperature-dependent Coulomb and proximity potential model give the least deviation from available experimental values, and therefore suggests that the two models (MGLM2 and CPPMT) are the most suitable for the evaluation of $\alpha$-decay half-lives for the $\mathrm{Hg}$ isotopes.
Alpha Decay Half-lives of Heavy and Superheavy Nuclei within a Deformed Double Folding Model
(2024) W. A. Yahya; O. J. Oluwadare; B. J. Falaye
Alpha decay study of Thorium isotopes using double folding model with NN interactions derived from relativistic mean field theory
(2021) W.A. Yahya; B.J. Falaye
Analysis of human biosignal information with developed application software for ECG, EMG, EEG and speech signals
(International Journal of Biosensors & Bioelectronics, 2018-06) Ajani Adegbenro Sunday, Olusope Micheal Alade, Oluwatayo Sandra Ajani, Oladosu Jamiu Alabi
This paper repots the development of a flexible, robust and user friendly application software for the analysis of human biosignal information. Biosignals are time-varying electrical signals observed in living beings, which can be continually monitored for clinical diagnoses with suitable software. For this research, application softwares for biosignal information were developed with C programming language on MPLAB 4000 ICE. Codes for the analysis and graphical interface session were written using MATLAB 2013a. The programmes were compiled; the system encased and tested successfully with 10 patients per hospital, at five University Teaching Hospitals in South Western Nigeria and development of robust and flexible application software for the analysis of biosignal data was also achieved.
Approximate Analytical Solutions of the Improved Tietz and Improved Rosen-Morse Potential Models
(2015-06-12) Yahya Wasiu Akanni; Issa Kazeem
In this article, the approximate analytical solutions of the improved Tietz and improved Rosen-Morse potential models are obtained using the parametric Nikiforov-Uvarov method. The energy eigenvalues and wave functions are obtained in the relativistic realm by solving the Klein-Gordon equation. Numerical results of the energy eigenvalues are obtained and studied.
Assessing leachate contamination and groundwater vulnerability in urban dumpsites: a case study of the Ipata Area, Ilorin, Nigeria
(Nigerian Society of Physical Sciences, 2024-04-21) Nurudeen K. Olasunkanmi; Damilola T. Ogundele; Victoria T. Olayemi; Wasiu A. Yahya; Azizat R. Olasunkanmi; Zulkifly O. Yususf; Samuel A. Aderoju
This study explores the extent of leachate contamination and groundwater vulnerability in urban dumpsites, with a specific focus on the Ipata area in Ilorin, Nigeria. The study employs a combination of 2D Electrical Resistivity Tomography (ERT), soil classification, and physicochemical analyses to investigate the percolation of leachate into groundwater and its potential environmental and health implications. The ERT data unveiled subsurface layers, highlighting the presence of decomposed topsoil down to approximately 1.2m. Beneath this layer, a low-resistivity zone (6.53 to 10.7 Ωm) indicated the potential risk of leachate percolation into groundwater. Soil classification revealed a shallow topsoil layer with insufficient clay content to hinder leachate penetration, emphasizing the need for enhanced containment measures. Physicochemical analysis of leachate, well water, and soil displayed variations in key parameters such as pH, electrical conductivity, total dissolved solids, and anion concentrations. Leachate exhibited high pH and electrical conductivity, suggesting elevated total dissolved solids, while well water remained within acceptable pH limits for drinking water. Heavy metal concentrations exceeded permissible WHO limits in topsoil, leachate, and well water, with cadmium presenting a high ecological risk. The absence of persistent organic pollutants (POPs) in the samples indicates a current focus on heavy metals as a primary concern. In conclusion, this study underscores the urgent need for proactive pollution abatement measures in urban dumpsites like Ipata. Regular monitoring of surface and groundwater quality is essential to safeguard public health and the environment.
Assessing leachate contamination and groundwater vulnerability in urban dumpsites: a case study of the Ipata Area, Ilorin, Nigeria
(2024) N. K. Olasunkanmi; Dr. D. T. Ogundele; Dr. V. T. Olayemi; Dr. W. A. Yahya; A. R. Olasunkanmi; Z. O. Yusuf; Dr. S. A. Aderoju
This study explores the extent of leachate contamination and groundwater vulnerability in urban dumpsites, with a specific focus on the Ipata area in Ilorin, Nigeria. The study employs a combination of 2D Electrical Resistivity Tomography (ERT), soil classification, and physicochemical analyses to investigate the percolation of leachate into groundwater and its potential environmental and health implications. The ERT data unveiled subsurface layers, highlighting the presence of decomposed topsoil down to approximately 1.2m. Beneath this layer, a low-resistivity zone (6.53 to 10.7 ?m) indicated the potential risk of leachate percolation into groundwater. Soil classification revealed a shallow topsoil layer with insufficient clay content to hinder leachate penetration, emphasizing the need for enhanced containment measures. Physicochemical analysis of leachate, well water, and soil displayed variations in key parameters such as pH, electrical conductivity, total dissolved solids, and anion concentrations. Leachate exhibited high pH and electrical conductivity, suggesting elevated total dissolved solids, while well water remained within acceptable pH limits for drinking water. Heavy metal concentrations exceeded permissible WHO limits in topsoil, leachate, and well water, with cadmium presenting a high ecological risk. The absence of persistent organic pollutants (POPs) in the samples indicates a current focus on heavy metals as a primary concern. In conclusion, this study underscores the urgent need for proactive pollution abatement measures in urban dumpsites like Ipata. Regular monitoring of surface and groundwater quality is essential to safeguard public health and the environment.
Assessing leachate contamination and groundwater vulnerability in urban dumpsites: a case study of the Ipata Area, Ilorin, Nigeria
(2024-04-21) N. K. Olasunkanmi, D. T. Ogundele, V. T. Olayemi, W. A. Yahya , A. R. Olasunkanmi, Z. O. Yusuf, S. A. Aderoju
This study explores the extent of leachate contamination and groundwater vulnerability in urban dumpsites, with a specific focus on the Ipata area in Ilorin, Nigeria. The study employs a combination of 2D Electrical Resistivity Tomography (ERT), soil classification, and physicochemical analyses to investigate the percolation of leachate into groundwater and its potential environmental and health implications. The ERT data unveiled subsurface layers, highlighting the presence of decomposed topsoil down to approximately 1.2m. Beneath this layer, a low-resistivity zone (6.53 to 10.7 Ωm) indicated the potential risk of leachate percolation into groundwater. Soil classification revealed a shallow topsoil layer with insufficient clay content to hinder leachate penetration, emphasizing the need for enhanced containment measures. Physicochemical analysis of leachate, well water, and soil displayed variations in key parameters such as pH, electrical conductivity, total dissolved solids, and anion concentrations. Leachate exhibited high pH and electrical conductivity, suggesting elevated total dissolved solids, while well water remained within acceptable pH limits for drinking water. Heavy metal concentrations exceeded permissible WHO limits in topsoil, leachate, and well water, with cadmium presenting a high ecological risk. The absence of persistent organic pollutants (POPs) in the samples indicates a current focus on heavy metals as a primary concern. In conclusion, this study underscores the urgent need for proactive pollution abatement measures in urban dumpsites like Ipata. Regular monitoring of surface and groundwater quality is essential to safeguard public health and the environment.
Assessment of image ratio technique: Targeting structural features and mineralization characteristics in the southwestern part of the Sokoto Basin in Nigeria using Landsat 8 imagery
(Kuwait Journal of Science, 2023-07-21) Nurudeen K. Olasunkanmi; Uthman Z. Magawata; Oyelowo G. Bayowa
Landsat 8 used multispectral images to map surface structures and validate the existence of suspected mineral alteration zones in the southwestern part of the Sokoto Basin in Nigeria. The area falls within contrasting sedimentary, metasediment, metamorphic, and older granitoid lithologies. The processing and analysis of the Landsat 8 imagery involving false color composite (FCC), band ratio, and principal component analysis (PCA) were implemented in the visible near-infrared and short-wave infrared bands of Landsat 8. PCA highlighted areas with high concentrations of clay minerals and iron oxides using RGB composite bands 7, 5, and 3. Moreover, PCA enhanced iron oxide, hydroxyl-bearing minerals, and likely prospective zones mainly constrained in amphibolite, phyllite, quartzite, and alluvial deposits that have undergone metamorphism and metasedimentation within Yegiwa and Kurege. It identified iron ore and clay mineral alteration, suggesting the occurrence of manganese, goethite, and carbonate minerals around Maburo and Derrena. The observed alteration zones and their associated quartz veins are usually consistent with the main NE–SW provincial structural trend dipping to the northwest zone. However, field verification validates rock units typically consisting of muscovite, hornblende, manganite, tourmaline, quartz vein, and granitic rocks. Accordingly, remote-sensing and field verification served as a guide for future subsurface structural investigation and in-depth geophysical exploration.
Bound state solutions of the Dirac equation for Scarf-Grosche potentials using the Nikiforov-Uvarov method
(2013-08) W. A. Yahya; K. J. Oyewumi
Bound state solutions of the relativistic Dirac equation with equal scalar and vector Eckart potential using the Nikiforov-Uvarov method
(2010-12) Yahya, W. A.; Oyewumi, K. J.; Akoshile, C. O.; Ibrahim, T. T.
Calculation of a complete set of spin observables for proton elastic scattering from stable and unstable nuclei
(2018-07-14) W. A. Yahya; B. I. S. van der Ventel; B. C. Kimene Kaya; R. A. Bark
Calculations of the alpha decay half-lives of some polonium isotopes using the double folding model
(2021-10) W. A. Yahya; K. J. Oyewumi
Cluster decay half-lives using relativistic density dependent double folding model
(2022) W. A. Yahya; T. T. Ibrahim
Comparative Studies of the alpha decay half-lives of 197 −220 Fr isotopes using the modified Gamow-like model and other empirical formulas
(2021-09) W. A. Yahya
Comparison of double-folding effective interactions within the cluster model
(2018) B. D. C. Kimene Kaya; S. M. Wyngaardt; T. T. Ibrahim; W. A. Yahya
Density-Dependent Parametrizations in B3Y-Fetal NN Interaction: Application to Alpha Decay
(2024) W. A. Yahya; O. K. Azeez; J. T. Majekodunmi; G. D. Olawale

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