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Research Article
Influence of Sand Particle Size Distribution on the Properties of Mortars Subjected to Various Temperatures
Issue:
Volume 14, Issue 4, December 2025
Pages:
88-94
Received:
1 October 2025
Accepted:
16 October 2025
Published:
31 October 2025
Abstract: The durability of concrete and mortar structures against extreme thermal stress is a major concern in Civil Engineering. This present experimental study aims to critically assess the influence of sand particle size distribution on the physico-mechanical and hydric characteristics of mortars after exposure to different temperatures. Cubic mortar specimens measuring 70 x 70 x 70 mm were manufactured using two types of sand (fine and coarse) of the same mineralogy, with a Sand/Cement ratio of 3 and a Water/Cement ratio of 0.5. The samples were subjected to five temperature levels: 20, 100, 150, 200, and 250°C. After cooling down to ambient temperature, several properties were measured, including mass loss, dimensional changes, bulk density, water absorption by immersion (total porosity), water absorption by capillarity, and compressive strengths. The results reveal a systematic influence of particle size: mortars made with fine sands exhibit a higher mass loss and consistently lower compressive strengths than those made with coarse sands, regardless of the applied temperature. In terms of hydric durability, fine sand mortars show lower water absorption by immersion (lower total porosity) but a higher absorption by capillarity, which indicates a microstructure characterized by finer but more interconnected pores, thereby favoring micro-cracking under thermal stress. In conclusion, the study demonstrates that sand particle size is a determining factor in the post-thermal performance of mortars, and the use of coarse sands is preferable to ensure better mechanical stability and increased resilience for structures exposed to temperatures up to 250°C.
Abstract: The durability of concrete and mortar structures against extreme thermal stress is a major concern in Civil Engineering. This present experimental study aims to critically assess the influence of sand particle size distribution on the physico-mechanical and hydric characteristics of mortars after exposure to different temperatures. Cubic mortar spe...
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Research Article
Investigation on Buffer Layers Influence on the Internal Quantum Efficiency of CH3NH3Sn(1-y)GeyI3 Lead-Free Perovskite-Based Solar Cells
Saliou Seck*
,
Alioune Sow,
Mamadou Salif Mane,
Modou Faye,
El Hadji Mamadou Keita,
Amadou Ndiaye,
Bachirou Ndiaye,
Babacar Mbow,
Cheikh Sene
Issue:
Volume 14, Issue 4, December 2025
Pages:
95-104
Received:
4 October 2025
Accepted:
18 October 2025
Published:
31 October 2025
Abstract: In this work, we have carried out a study in the modeling of photovoltaic devices based on lead-free perovskite materials, such as CH3NH3Sn(1-y)GeyI3, in which the germanium content varies from 0 to 1, using thin ZnO, TiO2 or SnO2, films as window layers. Thin Cu2O or NiO layers used as buffer layers ensure the n-p junction with the perovskite absorber material and act as an interface layer with the transport window layer. With the above window and buffer layer materials, photovoltaic devices have been designed. The study highlights the influence of geometric parameters such as the diffusion length of the minority carriers in the buffer layer as well as the thickness of this layer on the performance of photovoltaic devices. The evolution of the internal quantum efficiency is analyzed as a function of the window and buffer layer materials and also as a function of various other parameters including the thickness of the buffer layer materials and the minority carrier diffusion length in these materials. The results showed that NiO thin films offer better performances, especially when combined with ZnO or SnO2 window layers, respectively. The corresponding models with structures ZnO(n+)/NiO(n)/CH3NH3Sn0.75Ge0.25I3(p) and SnO2(n+)/NiO(n)/CH3NH3Sn0.75Ge0.25I3(p) give an internal quantum efficiency of 72.7% and 70.9% respectively.
Abstract: In this work, we have carried out a study in the modeling of photovoltaic devices based on lead-free perovskite materials, such as CH3NH3Sn(1-y)GeyI3, in which the germanium content varies from 0 to 1, using thin ZnO, TiO2 or SnO2, films as window layers. Thin Cu2O or NiO layers used as buffer layers ensure the n-p junction with the perovskite abso...
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Research Article
Effect of Buffer Layers Cu2O and KF Between Molybdenum and CIGS in the Electrical Parameters of CIGS Thin Film Solar Cells
Issue:
Volume 14, Issue 4, December 2025
Pages:
105-112
Received:
7 October 2025
Accepted:
21 October 2025
Published:
22 November 2025
Abstract: In this paper we have study the AZO/ZnO/CdS/CIGS/Mo/SLG heterojunction. We have study precisely the effect of Cu2O insertion between CIGS layer and Mo left contact. For this, we fix the Cu2O thickness at 100 nm. After this, we replace Cu2O by KF material with the same thickness. The use of those materials is motivated by their photovoltaic properties, their metallic content but also their non toxicity compared to PbS. By using SCAPS_1D software we have stimulated the effect of those buffer layers materials in electrical parameters as efficiency of solar cell, file factor, open-circuit voltage and short-circuit current density. Then, the efficiencies are around 24, 64% and 24.80% respectively for Cu2O and KF. We note that the efficiency increases at 21% to 24%. This introduction allows to establish a record efficiency for this kind of structure We note the same behavior for the file factor at 78.91% to 79.74% and 80.10% respectively for Cu2O and KF. These high electrical performances have obtained by using an Aluminum left contact and Molybdenum back contact. The functional temperature variation allows to obtain 26.20% and 25.99% efficiency for KF and Cu2O at 278.16 K. This functional temperature variation shows that by using phase change materials, we can attempt a record efficiency of 26%. This result is an improvement of 2% compared to ambient temperature. At the same time, this study shows that we have a big photovoltaic potential in the winter and in temperate area, near the pole area. This allows to find more recoiling technologies in order to improve more the efficiency of photovoltaic solar cells.
Abstract: In this paper we have study the AZO/ZnO/CdS/CIGS/Mo/SLG heterojunction. We have study precisely the effect of Cu2O insertion between CIGS layer and Mo left contact. For this, we fix the Cu2O thickness at 100 nm. After this, we replace Cu2O by KF material with the same thickness. The use of those materials is motivated by their photovoltaic properti...
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Research Article
Method of Producing Single-crystal Structures
Selivanov Viatcheslav*
Issue:
Volume 14, Issue 4, December 2025
Pages:
113-116
Received:
11 August 2025
Accepted:
13 October 2025
Published:
8 December 2025
DOI:
10.11648/j.am.20251404.14
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Views:
Abstract: Every year, the topic of growing single crystals becomes more and more relevant. Scientific and technological progress is rapidly moving into the future, and the technologies for growing single crystals remain unchanged for a long time. This article describes quite comprehensively and simply the process of growing single crystals by saturating the melting tank with free electrons, using the physical properties of some step-up transformers. In particular, a car ignition coil is a transformer capable of generating an electric charge that is easily transferred to a device or objects that are technologically unrelated to each other. The proposed method for obtaining single crystal structures is interesting in that the size of the resulting product is limited only by the size of the casting mold or the volume of the melting tank. Constantly growing demand forces manufacturers to expand production, automate most production processes, burn a large amount of non-renewable energy sources, create mountains of waste, and at the same time the cost of grown single crystals remains consistently high. The technology described in this article is able to solve most of the economic and environmental problems of industrial production of single crystals.
Abstract: Every year, the topic of growing single crystals becomes more and more relevant. Scientific and technological progress is rapidly moving into the future, and the technologies for growing single crystals remain unchanged for a long time. This article describes quite comprehensively and simply the process of growing single crystals by saturating the ...
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Research Article
Estimating the Product Quantity and Particle Size of Char and Activated Carbon Derived from Palm Kernel Shells – A Practical Approach
Issue:
Volume 14, Issue 4, December 2025
Pages:
117-126
Received:
29 October 2025
Accepted:
14 November 2025
Published:
8 December 2025
DOI:
10.11648/j.am.20251404.15
Downloads:
Views:
Abstract: In this study, activated carbons were prepared from palm kernel shells by physical activation. The methodology of experimental design was used to optimise the preparation conditions. While varying the particle size of the precursor palm kernel shells, carbonisation was done for about one hour to yield char. Activated carbon was prepared from the product char at a steam flow rate of 0.06 mol/h/g char and at a temperature of about 900°C for five hours. The empirical results were investigated to estimate the yield and particle size distribution of char and activated carbon produced from the palm kernel shells. Based on the yield and particle size analysis, a model was generated to predict product particle size and quantity in the production of activated carbon, thereby effectively utilising available raw materials and reducing preparation costs. In gold adsorption process, activated carbon of + 2.00 mm is mainly used to recover dissolved gold complexes from solutions. From data analysis and the model generated in this study, a relatively high composition of activated carbon with particle size + 2.00 mm was produced by utilising palm kernel shells precursor with particle size - 6.70 mm + 5.60 mm for carbonisation and char particle size –3.35 mm +2.80 mm for activation.
Abstract: In this study, activated carbons were prepared from palm kernel shells by physical activation. The methodology of experimental design was used to optimise the preparation conditions. While varying the particle size of the precursor palm kernel shells, carbonisation was done for about one hour to yield char. Activated carbon was prepared from the pr...
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