Physics
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Item HARVESTING RENEWABLE ENERGY FOR A SUSTAINABLE FUTURE USING QUANTUM DOT TECHNOLOGY(13th annual and international hybrid conference of the renewable and alternative energy of nigeria, 2025-03) Ikeri, H.I; Ndubueze, D. N; Eze, C. N.; Achuka, E. I; Nwagbara, O.; Onuabuchi, V. CThis paper explores the role of quantum dots in revolutionizing renewable energy technologies, addressing challenges such as stability and environmental impact. Renewable energy is essential for a sustainable future and advancements in nanotechnology have opened new possibilities for efficient energy harvesting. The result obtained indicates that quantum dots (QDs), display tunable electronic properties, discrete electronic state and high photon absorption efficiency. The novel properties allow for new design architectures such as immediate band, multiple exciton generation and multiple junction solar cell technologies. These mechanics have shown to derive quantitative gains in the solar to electricity conversion efficiency to surpass the Shockley and Quisser limit imposed on conventional cells. By integrating QD-based systems with solar photovoltaics and next generation batteries would paves the way for more efficient and sustainable energy solutions.Item Synthesis and Characterization of Chemically Deposited Doped Stannate Ternary Metal Oxide Thin Films and Their Solar Energy Applications(4th Africa Nano Conference and Workshop, 2021-07) Eze, C. N.; Onyia, A. I; Nnabuchi, M. NNano structured ternary metal oxide thin film like ZnSnO4 have receive much attention in the last decades owing to their unique properties rendering them suitable for wide range of applications. ZnSnO4 were grown by the chemical spray pyrolysis method. Home made spray pyrolysis technique is employed to prepared thin films. ZnSnO4 film was deposited on glas substrate using aqueous solution of zinc acetate dehydrate (Zn (CH3COO)2.2H2O and Tin (11) Chloride dehydrate or Stanic Chloride pentahydrate, SnCl2.5H2O as precursor at temperature of 2000C. the concentration of Zinc was varied from 0.001 to 0.005 while that of Tin was at 0.5. The product was annealed at 1hr at 2000C to improve its crystallinity. Various investigative techniques like XRD, SEM, EDX, UV-Visible, Raman spectroscopy analysis were carried out to find out the structural, morphological, spectroscopic and other properties of the ternary oxide thin film. The synthesized ZnSnO4 is of average crystalline size nano flowered having transmittance which increases with increase in wavelength. It has various band gaps which makes it find its application in photocatalysis and DSSCs (photoanode).SelfItem Electrode Materials for Energy Storage and Conversion(Tailor and Francis, 2022) Eze, C. N.; Obodo, R. M; Ezema, F. I; Kebede, M. AAlkaline earth stannates are rare earths and are crucial material systems evident of their attractive physical properties. They are ternary metal oxide semiconductors.They have both perovskite structures (BaSnO3, SrSnO3) and spinel structures(ZnSnO4).They are compounds of tin (Sn). Broadly, these compoundsexhibit elevated melting-points, elevated thermal stability, great thermal expansion coefficient, excellent chemical resistance, small thermal conductivity and great ionic conductivity which guarantee their possible applicacability in thermal barrier coating, hosts for luminescence centers, hosts for nuclear wastes, oxygen monitoring sensors, high-temperature catalysts, solar cells applicability and solid electrolytes in large temperature fuel cells. When these materials are produced as nanoparticles, the decreased particle size as well as enlarged specific surface area could result in diverse phase transition temperatures, improved catalytic activity, and enhanced processability. Commonly, these rare earth complex oxide nanomaterialscould be fabricated via conventional solid-state reactions, coprecipitation, sol-gel, hydrothermal, self-propagation techniques, etc.In the background of energy crisis, climate change, long-term supply and security, solar energy is a striking source. For these stannates to be better utilized in solar energy harvesting applications, they are better doped.The stannates considered here are SrSnO3, BaSnO3 and ZnSnO4.The doped stannates are used in various ways as stated above and equally as transparent conductors, light absorbers, photoanodes, etc. This is in relation to optical properties.The Optical properties, structural order and surface properties of these materials are considered. On doping, thesestannates maintain excellent transparency which makes them excellent materials as transparent conductor particularlyZnSnO4. They are found highly useful in photocatalysis and other areas.In solar energy harvesting, solar energy harvesting devices could have a better output when nanostructures like doped stannates are incorporated in them. Such advance is hopeful. It improves the power conversion efficiencies (PCE) of such devices by utilizing new nanostructures to update device structural designs. This is an applauded process.Item A STUDY OF CHEMICALLY DEPOSITED OXIDE- BASED TERNARY THIN FILM OF ZINC TITANATE (ZnTiO3) DOPED WITH NATURAL DYES AND THEIR POTENTIAL PHOTOVOLTAIC APPLICATIONS.(journal of nano and material science research, 2025) Eze, C. N.The ternary metal oxide thin film of ZnTiO3 doped with three different natural dyes were synthesized on glass substrate via solution growth (SG) at room temperature. Chemical baths were used which contained Zinc Sulphate (ZnSO4.7H2O), Sodium Hydroxide (NaOH), Titanium Chloride (TiCl3), distilled water and calibrated drops per bath of organic dyes: Lawsonia inermis, Beta vulgaries and Jatropha curcas respectively. Each deposit which was set at a temperature of 80 0C lasted for 1 h and each deposit was annealed at 400 0C for 1 h. These deposited nano thin films were characterized for their structural, morphological, optical properties, elemental composition and electronic (chemical) structure and presence of functional groups by means of X-ray diffraction (XRD), Scanning Electron Microscope (SEM), UV-VIS spectrophotometer, Energy Dispersive X-ray Fluoroscopy (EDXRF) and photoluminescence Fourier Transform Infrared Radiation Spectroscopy (FTIR). Polycrystalline thin films were evidenced which marked porosity offered them maximum surface area for dye loading which is critical for photosensitization in dye sensitized solar cells (DSSCs). Such doping presented band gaps of doped ZnTiO3 from 1.84 eV to 3.45 eV depending on dopants applied as against undoped film band gap that was 3.55 eV. The FTIR results showed good photophysical, carboxylate and modification properties of the dyes which helps in sunlight harvesting, anchoring and surface structure modification of the films. The dye influenced the optical properties of the samples and in particular, the reduction of the energy band gap, Eg from an increase in absorption coefficient α, giving high absorbance A, low extinction coefficient k, low reflectance R, which inferred its potential applications in solar energy devices when used in construction, poultry houses, solar cells and DSSCs.Item Optical Properties of PbSe, PbS, and PbTe Semiconductor Quantum Dots and their Applications(2025-08) Ikeri, H.I; Harry, S.T; Achuka, E.I; Eze, C. N.; Asielue, O.K; Ndubueze, N.DAbstract - Optical properties of PbSe, PbS, and PbTe semiconductors in confinement regimes have been studied using the Brus equation. The results indicate that QDs exhibit size-dependent optical behavior and, hence, tunable bandgaps and emission wavelengths as a consequence of quantum confinement. As the QD size decreases, the absorption edge and emission peak are blue-shifted for all three materials. It is found that PbSe QDs display significant quantum confinement even at larger sizes. Due to its relatively large exciton Bohr radius (~46 nm), as the size decreases from 10 nm to 2 nm, the bandgap increases from 0.27 eV to over 1 eV, shifting absorption and emission into the near-infrared (NIR), leading to applications into NIR photodetectors, solar cells, and biomedical imaging. Also, PbS QDs exhibit significant quantum confinement effects at smaller sizes due to their smaller exciton Bohr radius (~20 nm) compared to PbSe. The bandgap increases from 0.41 eV to around 1.5 eV as the size decreases from 10 nm to 2 nm, shifting absorption and emission from the NIR into the visible range. This is utilized in solar cells, visible to NIR photodetectors and LEDs. Furthermore, PbTe QDs also exhibit pronounced quantum confinement effects because of their relatively large exciton Bohr radius (~46 nm). The bandgap increases from 0.32 eV to around 1 eV as the size decreases from 10 nm to 2 nm, shifting absorption and emission into the NIR and Mid-Infrared (MIR) regions, making them excellent materials for infrared detectors, thermoelectric and MIR applications. Among the semiconductor materials studied, PbS QD typically exhibits the largest increase in bandgap with decreasing size, making them suitable for applications requiring larger bandgap tunability, followed by PbSe and PbTe. These different optical characteristics are due to their unique electronic properties and exciton Bohr radii.Item Effect of Natural Dye Co-Sensitization on the Performance of Dye-Sensitized Solar Cells (DSSCS) Based on Anthocyanin and Betalain Pigments Sensitisation(European Journal of Applied Sciences 9 (3): 140-146, 2017 ISSN 2079-2077, 2017-01-01) YUSUF Abubakar Sadiq; K.U. Isah; B.J. JolayemiDye-sensitized solar cells (DSSCs) were prepared using natural pigments containing anthocyanin and betalain extracted from Flame tree and Bougainvillea glabra flowers respectively as sensitizers. The dyes were used as lone sensitizers exploring anthocyanin and betalain separately and as co-sensitizers exploring the combined anthocyanin and betalain (water extract) and combined anthocyanin and betalain (ethanol extract) separately. The effects of the sensitizers on the performance of the DSSCs were investigated, the study reveals that all the cells possess comparable values of V of about 0.55 0.1 V. However, of the two lone sensitisers,oc betalain based device gave a better efficiency of 0.21% while anthocynin based device achieved 0.17 %, this is attributed to their different anchoring functional groups. The, combined anthocyanin and betalain dyes (water extract) had the highest conversion efficiency of 0.26 % suggesting dye synergic absorption effect as a result of co-sensitisation, the lower efficiency of 0.24 %) achieved by combined anthocyanin and betalain (ethanol extract) is attributed to the contributory effect of the extraction solventsItem Optimizing the resistivity of colloidal SnO2 thin films by ion implantation and annealing(Surfaces and Interfaces Volume 55, December 2024, 105325, 2024-11-01) YUSUF Abubakar Sadiq; Martin Markwitz; Zhan Chen; Maziar Ramezani; John V. Kennedy; Holger FiedlerTin oxide (SnO2) is a critical material for a wide range of applications, such as in perovskite solar cells, gas sensors, as well as for photocatalysis. For these applications the transparency to visible light, high availability, cheap fabrication process and high conductivity of SnO2 benefits its commercial deployment. In this paper, we demonstrate that the resistivity of widely colloidal SnO2 can be reduced by noble gas ion beam modification. After low energy argon implantation with a fluence of 4×1015 at.cm−2 at 25keV and annealing at 200°C in air, the resistivity of as-deposited film was reduced from (178±6)μΩcm to (133±5)μΩcm, a reduction of 25%. Hall effect measurements showed that the primary cause of this is the increase in carrier concentration from (8.1±0.3)×1020 cm−3 to (9.9±0.3)×1020 cm−3. Annealing at 200°C resulted in the removal of defect clusters introduced by implantation, while annealing at 300°C resulted in the oxidation of the films, increasing their resistivity. The concentration of oxygen vacancy defects can be controlled by a combination of low energy noble gas ion implantation and annealing, providing promising performance increases for potential applications of SnO2 where a low resistivity is crucial. Graphical abstractItem An insight into advanced glass systems for radiation shielding applications: A review on different modifiers and heavy metal oxides-based glasses.(CELL PRESS, 2024) Al-Buriahi, M. S., Kurtulus, R., Eke, C., Alomairy, S.; OLARINOYE, OYELEKEIonizing radiation from natural and many synthetic sources is a remarkable tool in many scientific, production, quality control, food preservation, medical, security, and other technological processes. The need to protect humans (public and personnel), gadgets, the environment, and animals from the harmful effects of radiation, while maintaining and expanding the scope of application has made radiation protection an important topic to discuss. Among the methods and materials available for radiation control, shielding and the use of glass shields are the most effective and attractive methods and materials, respectively. In this report, the basic parameters for measuring shielding competences, basic shielding materials and their shortcomings, and glass shields are discussed. Five categories of glasses, namely, borate, germanate, silicate, phosphate, and tellurites, with important shielding attributes, are reviewed. The role of chemical composition, density, and mean atomic number as gamma shielding delineating factors was emphasized. The weaknesses and comparable advantages of each glass system were presented as well. The review concludes by looking at the trend and future of glass shields and research in radiation technology. The data and analysis presented in this review provides scientists and radiation protection technologist on the impact of certain chemical oxides on shielding efficacies of different glass systems.Item Mechanical properties and radiological implications of replacing sand with waste ceramic aggregate in ordinary concrete.(ELSEVIER, 2024) OLARINOYE, OYELEKE; Kolo, M. T.,; Amuda, D. B., Oche, C. O., Mohammed, B., Alzahrani, J. S., & Al-Buriahi, M. S.The mining of aggregates for the production of concrete creates ecological problems. In this study, the effect of partially replacing sand as fine aggregate (FA) with waste ceramic tiles (WCT) on the density, compressive strength (CS), specific radioactivity of naturally occurring radioactive materials (238U, 232Th, and 40K), and the radiation shielding competence of concrete was investigated. Ordinary concrete samples consisting of cement, fine aggregate (river sand), coarse aggregate (granite), and water were prepared in 50 mm ×50 mm x 50 mm cubical steel moulds. The samples were coded as C-WCT0, C-WCT5, C-WCT10, C-WCT15, C-WCT20, and C- WCT25, representing concrete samples in which the FA component was replaced by 0, 5, 10, 15, 20, and 25% pulverized WCT, respectively. The CS and density of the samples were determined after 7-, 14-, and 28-day curing periods. The gamma spectrometric method was used to determine the specific activity of 238U, 232Th, and 40K using a hyper pure germanium detector. The photon and neutron shielding parameters of the concrete blocks were calculated with the aid of the EPICS2017 cross-section library and relevant standard formulae. The mean CS for each concrete category increase with curing age. The density of the concrete varied from 2213 kg/ m3 to 2488 kg/m3 as the FA replacement level rose to 15%. Using WCT as a partial replacement for FA altered the chemical composition and decreased the specific activities of 238U, 232Th, and 40K, in the concrete samples. C- WCT15 had the best gamma photon and fast neutron absorption features among the concrete samples. The use of WCT as aggregate in concrete production is a sustainable and environmental-friendly way of producing concrete for general civil engineering and shielding applications in medical and other radiation facilities. This study also affirms that using alternative materials with lower specific activity to replace sand is radiologically desirable in reducing the indoor radiation dose of occupants of concrete-based structures. The replacement of 15% sand by WCT produced stronger, radiologically safer, and more effective radiation absorbing concrete.Item Assessment of Environmental Background Gamma Radiation Variation in Minna Area of Nigeria(Taylor and Francis, 2024) Adeiza Stephen, A.,; OLARINOYE, OYELEKE; Kolo, M. T.,; Kasim, I.Radiation has been acknowledged to be responsible for deleterious conditions in living tissues. Hence, environmental background gamma radiation (BGR) measurement is crucial from an environmental and health perspective. In this study, due to the absence of comprehensive background gamma radiation data and the increasing numbers of anthropogenic activities that could increase the BGR level, such as where mining activities are active. The BGR in the Minna area of Niger State, Nigeria, was measured and analyzed in this study. In-situ measurement of the background gamma radiation level was carried out using a well-calibrated portable handheld GQ GMC-500 Plus nuclear radiation detector at an elevation of about 1.0m above ground level. global positioning system from Garmin (GPSmap 78s) was adopted for identifying geographical locations. A total of 1172 points were surveyed across the study area for background environmental radiation. The BGR values ranged from 0.102 to 0.147 lSv/h, with an overall mean value of 0.126 lSv/h. The average measured dose rate was more than twice the reported world average value of 0.059 lSv/h. The annual effective dose equivalent (AEDE) for the research area was calculated to be 0.221 mSv/y on average. The mean AEDE is lower than the ICRP recommended limit. This shows that the population of the Minna area is radiologically safe based on the estimated AEDE value. Similarly, the excess lifetime cancer risk (ELCR) value ranged from 0.626�10 0.774±0.09�10 −3 −3 to 0.901�10 −3 mSv/y with a mean value of mSv/y. The mean value of AEDE is below the 0.24 mSv/y permissible limits as recommended by the International Commission on Radiological Protection (ICRP). The mean ELCR value exceeds the average world value of 0.29�10 −3 . Also, the mean organ dose values estimated for the whole body, liver, kidney, testes, bone marrow, ovaries, and lungs are 0.150±0.02, 0.102±0.01, 0.137±0.02, 0.181±0.02, 0.152±0.02, 0.128±0.02 and 0.141±0.02 mSv/y respectively. The differences in the calculated mean of BGR were attributed to natural and human factors. Geological variation is a fundamental factor that influences the changes in BGR. Human activities, mining, building materials, and the use of phosphate fertilizers in agricultural practices are responsible for the differences in BGR. The ELCR implies that terrestrial gamma radiation does not pose any immediate radiological health effects on residents of the area, but there is a tendency for long-term health hazards in the future, such as cancer, due to the dose accumulated