Papers by Keyword: Nanomaterials

Abstract: In this study, CuFe₂O₄ nanoparticles with an average crystallite size of approximately 10 nm were produced using the sol-gel autocombustion method. The synthesis was conducted in the presence of polymers with varying monomer counts, aiming to optimize the magnetic properties for possible localized magnetic heating applications. Comprehensive characterization of all samples was conducted using X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier-transform infrared spectroscopy (FT-IR), and Mössbauer spectroscopy. All synthesized samples exhibited good colloidal stability, with zeta potentials around -18.49mV, +3mV and +24 to +30 mV. The Specific Absorption Rate (SAR) of the synthesized nanoparticles was assessed using the calorimetric method. The SAR values were calculated using both the Initial Slope and the Box-Lucas methods. For the sample synthesized using citric acid, the SAR values were 12.6 W/g and 13.23 W/g, respectively. For samples synthesized using polyethylene glycol, the SAR values ranged from 3 to 7 W/g. The parameters of the alternating magnetic field were 33.3 kA/m and 357 kHz.

Abstract: A new form of composite PCMs is developed by adding 0.5 wt% of SiO₂, TiO₂, ZnO and CuO nanomaterials to lauric acid. Phase change temperatures of lauric acid range from 43.92°C to 44.65°C and 40.84°C to 41.36°C, respectively. In addition, the phase change latent heats are 183.23 kJ/kg and 183.68 kJ/kg at room temperature, respectively. Thermal properties of PCM with nanomaterials were discussed in terms of weight fractions. The improvement in thermal conductivity of the PCM owing to the dispersion of nanomaterials was verified by laser flash analyser (LFA). Hence, the newly developed composite PCMs holds great potential as a candidate for harnessing solar energy in low-temperature heating systems. Keywords: Phase Change Material (PCM), Melting, freezing, Nanomaterials and Lauric acid.

Abstract: Research of green-synthesized reduced graphene oxide (rGO) using Amaranthus viridis (AV) extract has been successfully conducted. The modified Hummers method was used to synthesize graphene oxide (GO), then reduced using hydrazine hydrate and AV extract to obtain rGO. The X-ray diffraction results illustrate the change in crystalline structure from graphite to rGO. Peaks at 2θ angles of 26.5°, 9.1°, and 24.1° indicate the characteristics of graphite, GO, and rGO, respectively. The transmission electron microscopy image shows the formation of 2D nanosheet morphology with slight wrinkles. The fourier transform infrared spectrum represents six peaks of identical functional groups in the graphene-based nanomaterials. Meanwhile, GO has two additional oxygen groups (carboxyl and hydroxyl) at wavenumbers of 1720 cm^-1 and 1217 cm^-1, respectively. Furthermore, the UV-Vis analysis data shows the typical absorption of GO at 232 nm and 301 nm, while at 266 nm and 278 nm, it belongs to graphite and rGO. The bandgap energy of nanomaterials is 0–3.58 eV, which describes the difference in their optical properties. These promising results reveal the potential of AV as a green-reducing agent to minimize the use of chemicals in the synthesis of rGO for various applications.

Abstract: Nanoscale mixed ferrites with a spinel structure are highly versatile materials widely employed across diverse fields, including engineering, biomedicine, and ecology. This study explores the influence of pH on the structure, morphology, electrophysical, and mechanical properties of CuFe₂O₄ spinel, synthesized using the sol-gel self-combustion method. The investigation reveals that the pH level significantly impacts the structure formation, even at the gel formation stage, thereby shaping the subsequent structure and properties of the synthesized ferrite. X-ray diffraction (XRD) analysis demonstrates that the dominant phase (>90%) corresponds to the cubic spinel phase with the chemical formula CuFe₂O₄, belonging to the Fd3m space group. Notably, the pH of the reaction medium exerts a profound influence on the distribution of iron and copper ions within the octahedral and tetrahedral sublattices of the spinel structure. This variation in cationic distribution manifests in notable changes in the synthesized ferrite's magnetic, mechanical, and degradation properties. Furthermore, the study delves into the impact of the synthesized CuFe₂O₄ spinel as a photocatalyst for degrading organic dyes through the photo-Fenton process. It demonstrates that degradation efficiency is closely related to the ferrite's band gap width and particle size. This study aimed to determine how the pH of the reaction medium impacts the structure, morphology, optical, mechanical, and magnetic characteristics of the nanosized ferrites being synthesized. Furthermore, the synthesized materials were evaluated for their photocatalytic abilities in degrading organic dyes in water. The ferrite powders showcased remarkable dye degradation capabilities via the photo-Fenton process. Degradation efficiency largely hinged on the band gap width and the size of the particles. The most notable outcome was achieved with sample P1, which had particle sizes averaging 12.14 nm. By unraveling the complex relationship between pH, structure, and properties, this research enhances our understanding of the design and optimization of nanoscale mixed ferrites.

Abstract: The discovery of Carbon Nanotubes (CNT) has opened the doors for revolutionary applications in the mechanical, aerospace, and electrical sectors. However, to fully utilize the potential of carbon nanotubes, there is a persisting need to identify all sorts of structural modifications that can be observed in any type of manufacturing procedure for CNTs. Thus, the presented study investigates the mechanical properties of CNTs with variable waviness and defect density. Furthermore, the study is performed using classical Molecular Dynamics simulations (MD). The structures are then characterized with single or multiple vacancy defects along the axis of the nanotube structure, which is modeled as wavy structures to replicate their natural structure. After the simulation results were analyzed, it was observed that the increase in the surrounding temperature from 300K to 1500K reduces the overall tensile strength of the CNT sample from 89-47 GPa. However, introducing a single vacancy defect to the same structures was shown to reduce the tensile strength to 41 GPa at 1500K and 62 GPa at 300K.

Abstract: The conductivity of cement-based materials is usually poor, and this material is not a common conductive material. However, with the rapid development of Internet of Things technology in recent years, the rise of smart cities has brought more and more opportunities and needs, and conductive cement-based materials have emerged. Conductive cement-based material is a new type of composite material. The conductive material is added to the cement-based material to reduce its resistance and enhance the conductive properties of the material. The material can not only be applied to the construction of smart cities, such as smart street lamps and smart roads but also can be widely used in buildings, public transportation, and other fields. In the study of conductive cement-based materials, the size and shape of conductive materials have a direct impact on the electrical conductivity of cement-based materials. This is because the dispersion of the conductive material has a significant effect on the conductivity, and the size and shape of the conductive material can determine its dispersion. Secondly, in the application environment of cement-based materials, factors such as humidity and cracks may affect electrical conductivity. Therefore, to ensure the stability and reliability of conductive cement-based materials, a large number of experimental studies are needed to optimize the dispersion and shape of conductive materials and to understand the performance of materials in different environments. The research of conductive cement-based materials is of great significance to the construction of smart cities in the future. This conductive material has great application prospects, which can not only improve the intelligent level of urban infrastructure but also bring more social and economic benefits.

Abstract: Nanocrystalline materials have different properties compared to materials with microcrystalline grains. Nanocomposites, as a subdivision of nanomaterials, have different magnetic properties for each individual constituent. In the paper, a series of nanocomposite materials from the sphere of W ferrites are developed by mechanical grinding. Mixtures of commercial BaO and α-Fe₂O₃ powders, in the micron range, were used. The commercial powders were mechanically ground in order to reach the nanometric range. The use of suitable grinding parameters for ceramic powders led to the discovery of the nanometric range in a not very long time. An important parameter, which was used in the current research, was wet grinding which is a more suitable method for obtaining finer powders than dry grinding. Dividing the materials as finely as possible ensures a better reactivity due to the free valences of the ions on the surface of the granules and due to the fact that the number of contact points and the contact surface are much larger than in coarse-grained materials. The powders were unilaterally compacted, using a cylindrical die with an inner diameter of 15 mm. A resistive heating device was designed and built in order to assure the sintering process of the samples. Before resistive sintering, a thermal simulation of the heating process was carried out to see the distribution of the thermal field in the samples at different temperatures. According to the simulation, the optimal heating temperature was chosen. The sintered samples were analyzed from the point of view of the magnetic properties and it was found that the samples with the granulation in the nanometric range have higher magnetic characteristics than those in the micron range.

Abstract: The results of research into new materials are increasingly pushing the boundaries of science and technology. For some of the materials, such as polymers, composites and nanomaterials, new knowledge is expected in the future. However, new knowledge is also being gained in the case of metal alloys, which were considered to have been fully investigated. Thus, in 2018, new knowledge emerged about materials that are believed to be able to significantly influence many areas of modern society. They include seven completely different materials such as polymers, nanocomposites, and metal alloys. The materials are Wood Sponge – the greener way to clean up oceans; the strongest bio-material – stronger than steel and its biodegradable; self-healing material – it does it without external stimulant; Platinum Gold Alloy – matching Diamond in wear resistance; Silicon X – better than the original; Indefinitely recyclable plastics – making a case for the future of plastics; and Glass coating that can block sunlight. In this paper, an overview of knowledge about them is given, and their application characteristics are highlighted.

Abstract: Carbon Dots (CDs) have gained the attention of many researchers since its discovery in 2004 due to their unique nanostructure and properties. These are very promising carbonaceous nanomaterials having wide range of applications in sensors, imaging, energy storage, nanomedicine, electrocatalysis and optoelectronics. CDs have shown excellent physical and chemical properties like, high crystallization, good dispersibility and photoluminescence. Besides, these are now known to have excellent biocompatibility, long-term chemical stability, cost-effectiveness and negligible toxicity. Due to favourable physical structure and chemical characteristics, these nanocarbon-based materials have drawn an interest as supercapacitor (SC) electrode materials, opening upnew opportunities to increase the energy density and lifespan of SCs. Thus, variety of quick and affordable methods i.e., the arc-discharge method, microwave pyrolysis, hydrothermal method, and electrochemical synthesis have been developed to synthesize this versatile nanomaterial. There are undoubtedly many methods for creating CDs that are effective and affordable, but due to the safety and simplicity of synthesis, CDs made from waste or using environmentally friendly methods have been innovated. In order to devise sustainable chemical strategies for CDs, green synthetic methodologies based on "top-down" and "bottom-up" strategies have been prioritised. This review summarizes numerous synthetic strategies and studies that are essential for the creation of environment friendly processes for CDs. The recent developments in the use of CDs for photoluminescence and supercapacitance have been highlighted providing a clear understanding of the new source of energy and optoelectronic materials with a futuristic perspective.

Abstract: The research in nanocomposites is accelerating with greater velocity due to its wide range of properties and applications in various sectors like construction, marine, automobile, aerospace, defense, and biomedical fields. Most of the researchers are trying to improve the properties further by dispersing various nanomaterials to the matrix to improve the matrix properties. In the present review article, we have discussed in brief the nanocomposites and their various synthesis routes along with their advantages and disadvantages. Why nanocomposites are more preferable over conventional composite materials is also discussed. Important characterization techniques like X-Ray diffraction (XRD), scanning electron microscope (SEM), transmission electron microscope (TEM), Fourier-transform infrared spectroscopy (FTIR), thermogravimetry (TG) and differential scanning calorimetry (DSC) used to investigate the nanocomposites are also discussed.