Spherical Grains Research Articles

Photovoltaic Properties of Bismuth Vanadate/Bismuth Ferrite Heterostructures Prepared by Spin Coating

This study investigates the photovoltaic performance of bismuth vanadate (BiVO₄)/bismuth ferrite (BiFeO₃) heterostructures. By varying the pre-annealing temperature of the BiVO₄ layer, we have achieved significant enhancement in the open-circuit voltage (Voc) with the spontaneous formation of the polarized Bi4V2O11 interfacial layer. X-ray diffraction analysis confirms a pure rhombohedral distorted perovskite structure for BiFeO₃ and a monoclinic crystallographic nature for BiVO₄. SEM analysis exhibits a porous structure with small spherical grains in the BiVO₄ layer, with the dense and smooth surface of the BiFeO₃ layer. The heterostructures represented in a red-shifted absorption edge are compared with the individual materials, which indicates an improved light absorption. Tauc plot analysis has yielded the direct bandgap values of 1.88 eV and 1.83 eV for the BiVO4 annealing temperatures at 150 and 500°C, respectively. The overall power conversion efficiency (η) has remained low at 0.003% and 0.005%, demonstrating the potential of interfacial engineering to optimize the photovoltaic properties of BiVO₄/BiFeO₃ heterostructures.

Synthesis and Characterizations of Structural, Dielectric and Optical Properties of CCTO– PT Composite

In this study, we have synthesized the (1-x) CaCu3Ti4O12 – (x) PbTiO3 (CCTO-PT) composites with x = 0.00, 0.50 and 1.00 by using the solid-state method. We have then studied the structural, optical and dielectric properties of these composites. The X-ray diffraction diffractogram (XRD) showed that the ceramics at x = 0.00 and 1.00 (CCTO and PT) crystalize in a pure cubic and tetragonal phase respectively. Likewise, for CCTO-PT composite, we observed a coexistence of tetragonal and cubic phase in CCTO-PT composite composites. The scanning electron microscopy (SEM) micrographs showed homogeneous microstructure samples and consist of different grain shape. The large spherical grain structure is attributed to CCTO ceramic while the smaller grain form can be ascribed to the PT ceramic. The dielectric measurements results revealed an increase in dielectric permittivity value for CCTO-PT composite compared with pure CCTO and PT. The optical band gaps of the CCTO and PT are 2.50 and 3.00 eV, and increased to 3.50 eV for the CCTO/PT composite.

Chemical spray pyrolysis deposited ZnO/ZIF-8 and cobalt doped ZnO/ZIF-8 composite thin films for highly sensitive and selective ammonia sensing at room temperature

ZnO is a widely studied metal oxide for gas sensor applications concerning its biocompatibility and physio-chemical properties. However, the high operating temperature and low response are drawbacks. ZIF-8, the metal-organic framework of Zinc and imidazolate, is renowned for its gas adsorption property. The poor stability of ZIF-8 also limits its application as an effective gas sensor. Thus, a composite thin film of ZnO and ZIF-8 is deposited on a glass substrate using the chemical spray pyrolysis technique to detect ammonia at room temperature (300 K). The composite thin film is stable, has a good response, and is repeatable. Further, to enhance the sensor response at room temperature, Co is doped to the ZnO/ZIF-8 composite thin films. The sensor response for 1 ppm of ammonia for the Co doped ZnO/ZIF-8 is 301 at room temperature. Along with the gas adsorption capability of ZIF-8 providing more active sites, the change in morphology from flakes to spherical grains on doping with Co provided higher active surface area and free electrons and all together instigated fast redox reaction and conduction mechanism in ZnO. Hence, the Co doped ZnO/ZIF-8 composite thin films have an enhanced response of 117,285 to 50 ppm of ammonia.

Averaging of the model of a chemical process in a catalyst layer with a spherical grain

The article presents a comparative analysis of models of a non-stationary chemical process using the example of burning coke sedimentation from a catalyst layer with a spherical grain. The first model is obtained by averaging the heat conductivity equation for a spherical catalyst grain. The second is the averaging of the entire grain model, including the diffusion-reaction equations. The comparative analysis showed good consistency of the results under conditions of low concentrations of reagents, small catalyst grains and high process temperatures with a significant reduction in calculation time for the first model. It was found necessary to take into account intradiffusion inhibition at the case of a high reagent concentrations. It causes the occurrence of a concentration gradient along the radius of the catalyst grain at the initial stages of the process. В статье представлен сравнительный анализ моделей нестационарного химического процесса на примере выжига коксовых отложений из слоя катализатора со сферической формой зерна. Первая модель получена осреднением уравнения теплопроводности для сферического зерна катализатора. Вторая - осреднением всей модели зерна, включая уравнения диффузии-реакции. Сравнительный анализ показал хорошую согласованность результатов в условиях низких концентрациях реагентов, малом зерне катализатора и высоких температурах течения процесса при существенном сокращении времени расчета для первой модели. При высоких концентрациях реагента выявлена необходимость учета внутридиффузионного торможения, обуславливающего возникновение градиента концентраций по радиусу зерна катализатора на начальных этапах процесса.

Investigating the Thermal Decomposition of BP into B12P2: Experimental Insights and Kinetic Modelling at High Temperatures

This study investigates the thermal decomposition of BP into B12P2, with a particular focus on the heterogeneous solid-gas mechanism involving BP powders synthesized via self-propagating high temperature reactions. Various techniques, including XRD, TGA, SEM, TEM, EELS and SAED, were combined to examine morphological and structural changes at different temperatures. The results reveal an ignition temperature for decomposition at 1120°C, beyond which BP grains undergo fragmentation into smaller particles, accompanied by the release of phosphorous gases (P2(g), P4(g)). Additionally, Rietveld refinements on thermally treated powders facilitated the determination of advancement rate values of the decomposition reaction under different isothermal conditions. Based on these kinetic data obtained at 1300°C, a one-process nucleation-growth model with instantaneous nucleation and anisotropic growth has be established. In particular, the law, which describes the process for a spherical grain with inward development and a reaction occurring at the internal interface as the step determining the rate, displayed a strong correlation coefficient, offering novel insights into the kinetic evolution of the BP to B12P2 conversion. These results contribute to a deeper understanding of the thermal decomposition process and its underlying elementary mechanisms.

Clay Minerals and Continental‐Scale Remagnetization: A Case Study of South American Neoproterozoic Carbonates

AbstractThe Neoproterozoic carbonate rocks of the Araras Group (Amazon Craton) and the Sete‐Lagoas and Salitre Formations (São Francisco Craton) share a statistically indistinguishable single‐polarity (reversed) characteristic direction. This direction is associated with paleomagnetic poles that do not align with the expected directions for primary detrital remanence. We employ a combination of classical rock magnetic properties and micro imaging/chemical analysis (in thin sections) using synchrotron radiation to examine these remagnetized carbonate rocks. Magnetic data indicate that most samples lack the anomalous hysteresis properties typically associated with carbonate remagnetization (except for distorted loops). Through a combination of Scanning Electron Microscopy with Energy Dispersive X‐ray Spectroscopy (SEM‐EDS), X‐ray Fluorescence (XRF), and X‐ray Absorption Spectroscopy (XAS), we identified subhedral/anhedral magnetite, or spherical grains with a core‐shell structure of magnetite surrounded by maghemite. These grains are within the pseudo‐single domain size range, as do most of the iron sulfides, and are spatially associated with potassium‐bearing aluminosilicates. While fluid percolation and organic matter maturation play a role, smectite‐illitization appears to be crucial for the growth of these phases. X‐ray diffraction analysis, in addition, identifies these silicates as predominantly highly crystalline illite, suggesting exposure to epizone temperatures. These temperatures were likely reached during the final stages of the Gondwana assembly (Cambrian), but remanence was only locked in afterward, in successive cooling events during the Early Middle Ordovician. This is supported by the carbonates' paleomagnetic pole positions compared to Gondwana's apparent polar wander path, and the absence of reversals, contrasting with the high reversal frequency of the Late Ediacaran/Cambrian.

Crystal Structure, Optical, Photoluminescence, Raman, and Magnetic properties for Sm-doped Cr-Mg-Bi Ferrites using sensor

The current work,A series of rare earth Sm3+ ion substituted Cr-Mg-Bi ferrites Cr0.7Mg0.2Bi0.1SmxFe2-xO4 (x = 0.00, 0.02, 0.04, and 0.06) have beensynthesized by thesol-gel auto-combustion method. The XRD, FESEM, HRTEM,UV-Vis, FTIR, Raman spectroscopy, Photo Luminesce and Magnetic Properties analysis have been used to investigate structural, morphological, optical, Raman spectroscopy, Photo Luminesce and Magnetic Properties. Every sample contains a single-phase spinel structure, as confirmed by XRD.The substitution of Sm3+ ions is found to increase the lattice parameter from 8.258–8.248Å.A monotone diffraction peak (311) is visible near small angles of degrees (35.33 to 35.13). The Debye-Scherrer equation, the nanoparticles' crystallite size ranges from 35.357–54.778 nm.FE-SEMs reveal a spherical grain that groups and has a porous form, with particles 38.13 to 53.28 nmin size.HR-TEM micrographs illustrate spherical morphology and their average particle size decreases from 55.32 to 65.42 nm. The selected area electron diffraction (SAED) pattern confirms the crystal planes which were revealed from XRD calculations.The spinel structure was confirmed by FTIR spectroscopy, which found 414 cm-1 and 516 cm-1 vibrational band at the octahedral and tetrahedral sites.As the concentration of Sm3+ rises, the direct and indirect band gap energy values determined from UV-Vis show an increase and decrease.The generated NPs' semiconducting nature is confirmed by the strong correlation between the g-value and particle size change.Photoluminescence (PL) investigation shows that all processed samples have four bands.(i) peak centered at 412 nm, which is near-band edge emission and corresponds to the ultraviolet (UV) band,(ii) The violet band has a high-intensity peak at 434 nm,(iii) The blue band is related to a low-intensity, sharp peak located at 466 nm, and (iv) A broad peak at 502 nm with a very low intensity distinguishes the green band.The Raman spectroscopy investigation revealed that the CMBSF nanoparticles had a mixed spinel structure. The magnetic investigation shows that when the Sm content of ferrites increases, saturation magnetization drops from 39.86 to 33.16 emu/g.The sample's coercivity (Hc) increases from 16.06 to 21.90 KOe with Sm substitution.

Effect of crystallization behavior on wear properties of polytetrafluoroethylene composites modified by irradiation above melting point

AbstractIn this paper, the reasons for the improved wear resistance of irradiation‐modified Polytetrafluoroethylene (RM‐PTFE) and its composites above the melting point were investigated from the microcrystalline point of view by using methods such as crystallization kinetics, and it was found that the linear wear rate of RM‐PTFE was only 0.3 um/km, with a 1000 times increase in wear resistance, which was due to the transformation of its crystals from flake crystals that were easily dislodged to spherical crystals that were more resistant to abrasion. It was also found that the linear wear rate of Polytetrafluoroethylene (PTFE) with coke and graphite was 0.2 and 0.1 μm/km, respectively, and the abrasion resistance was further improved, which was attributed to the lowering of spherical crystal grain size by coke and graphite, which had better mechanical properties. These studies lay the foundation for future research on the frictional wear mechanism of RM‐PTFE above the melting point.Highlights Irradiation‐modified PTFE above the melting point Wear resistance of PTFE increases 1000 times Changes in crystal morphology dramatically increase wear resistance Use of crystallization kinetics to study the crystalline form of PTFE Small grain size improves wear resistance

Facile synthesis of reduced graphene oxide-zirconium oxide/zinc oxide nanocomposites for effective antimicrobial and cytotoxic applications

In this study, reduced graphene oxide (rGO) was successfully synthesised and impregnated with ZrO2-activated ZnO nanoparticles using facile chemical technique to obtain rGO-ZrO2/ZnO nanocomposites for effective biomedical applications. Fourier transform infra-red and X-ray diffraction results were authorized the rGO-ZrO2-ZnO nanocomposites formulation. Scanning electron micrographs showed wrinkled sheets integration of agglomerated spherical grains with hillocks and voids for rGO-ZrO2/ZnO. UV–vis and photoluminescence spectral results proved the modulated electronic structure in the nanocomposites. An extensive investigation was done for synthesised rGO, ZnO, rGO-ZnO and rGO-ZrO2/ZnO against human lung cancer (A549) cell lines. The exposed outcomes revealed the high cytotoxic behaviour against the cancer cell lines by the rGO-ZrO2/ZnO nanocomposites. Moreover, the antimicrobial efficacy of rGO-ZrO2/ZnO nanocomposites exhibited a potential bactericidal effect against S. aureus and E. coli organisms related to rGO-ZnO. Thus, the synthesised rGO-ZrO2/ZnO nanocomposites depicted high, thermal stability and potential bactericidal properties which could be the possible candidate for effective biomedical applications.

Enhanced etching of GaN with N2 gas addition during CVD diamond growth

Diamond on GaN materials processing is not straight-forward, as GaN is susceptible to a quasi-pure hydrogen CVD plasma etching. 1%, 3% and 5% N2 gas was gradually added to the H2 gas with fixed 6% CH4 in the recipe to promote the growth of diamond nanocrystals. Different types of microstructures were produced, with addition of nitrogen to the precursor gas recipe. Nitrogen gas changes the diamond film microstructure from faceted to spherical grains, with signs of GaN etching. The FWHM of the sp3 carbon Raman peak was calculated to be 6.5 cm−1, when there was no nitrogen gas in the precursor recipe, which deteriorates to a large extent after successive addition of N2. Fourier transform infrared spectroscopy (FTIR) showed a strong presence of the nitrogen related defects (peak positions at 1190 and 1299 cm−1) inside the nanocrystalline diamond (NCD) films grown with N2 addition. GaN layer etching from the base substrate by the CVD plasma was clearly evidenced by energy dispersive X-ray spectra (EDS) of the deposited films. Al elemental EDS peaks from the base sapphire substrate were observed for the films grown with nitrogen addition, but no Ga EDS peaks were detected. X-ray diffraction (XRD) micrographs further supported the enhanced GaN etching phenomenon. The electrical resistivity of the uncoated GaN was initially measured to be 22.2 Ω-cm. However, the resistivity rose to 1.59 × 106 Ω-cm after the nitrogen assisted film deposition; due to the GaN etching - thereby exposing the underlying insulating sapphire substrate.

Effect of the Particle Size Distribution of the Ballast on the Lateral Resistance of Continuously Welded Rail Tracks

While the effect of ballast degradation on lateral resistance is noteworthy, limited research has delved into the specific aspect of ballast breakage in this context. This study is dedicated to assessing the influence of breakage on sleeper lateral resistance. For simplicity, it is assumed that ballast breakage has already occurred. Accordingly, nine granularity variations finer than No. 24 were chosen for simulation, with No. 24 as the assumed initial particle size distribution. Initially, a DEM model was validated for this purpose using experimental outcomes. Subsequently, employing this model, the lateral resistance of different particle size distributions was examined for a 3.5 mm displacement. The track was replaced by a reinforced concrete sleeper in the models, and no rails or rail fasteners were considered. The sleeper had a simplified model with clumps, the type of which was the so-called B70 and was applied in Western Europe. The sleeper was taken into consideration as a rigid body. The crushed stone ballast was considered as spherical grains with the addition that they were divided into fractions (sieves) in weight proportions (based on the particle distribution curve) and randomly generated in the 3D model. The complete 3D model was a 4.84 × 0.6 × 0.57 m trapezoidal prism with the sleeper at the longitudinal axis centered and at the top of the model. Compaction was performed with gravity and slope walls, with the latter being deleted before running the simulation. During the simulation, the sleeper was moved horizontally parallel to its longitudinal axis and laterally up to 3.5 mm in static load in the compacted ballast. The study successfully established a relationship between lateral resistance and ballast breakage. The current study’s findings indicate that lateral resistance decreases as ballast breakage increases. Moreover, it was observed that the rate of lateral resistance decrease becomes zero when the ballast breakage index reaches 0.6.

High‐Performance Electrode for Energy Storage Developed Using Single‐Source Precursor‐Driven Bas:Cos:La2S3 Trichalcogenide Semiconductor

Using single‐source precursor route, this work reports the synthesis of the novel chalcogenide heterosystem, i.e., BaS:CoS:La2S3 trichalcogenide heterosystem. With the narrowed band gap energy, BaS:CoS:La2S3 expresses excellent photonic response with 3.47 eV of tailored band gap resulting from chemical synergism. This chalcogenide is marked by superior crystallinity and possessed an average crystallite size of 18.29 nm. Morphologically, BaS:CoS:La2S3 exists in the form of the roughly spherical grains arranged in the irregular manner. The developed chalcogenide is assessed for charge storage by fabricating the electrode using a nickel form as a support. In a 0.1 m KOH background electrolyte, the BaS:CoS:La2S3 adorns electrode excelled in achieving a specific capacitance of 967.24 F g−1. In addition, this trichalcogenide expresses the specific power density of 1659 W kg−1. Fabricated electrode retains original capacitance after different cycles. Regarding electrode–electrolyte interactions, the fabricated electrode shows minimal resistance, with an equivalent series resistance (Rs) of 1.42 Ω as indicated by impedance studies. Additional circuit elements, including CPE (Yo = 2.17 × 10−04, n = 0.71) and Rct (6.97 Ω cm−2), are obtained after circuit fitting for the BaS:CoS:La2S3 trichalcogenide decorated electrode. Exhibiting stable behavior for 43 h, the synthesized material demonstrates profound durability and functionality.

Comprehensive investigation on ruthenium doped Sn2S3 thin films for photo sensing applications

This study investigates the deposition of tin trisulfide (Sn2S3) films onto glass substrates through the nebulizer spray technique, employing aqueous solutions of SnCl2 and SC (NH2)2 at a molar ratio of Sn to S of 1:2 under various doping concentrations of ruthenium (1, 2, 3, 4, and 5 wt %). The crystallography, morphology, chemical, optical and photo sensing characteristics of deposited thin films has been comprehensively analysed using an X-ray diffractometer, Field emission scanning electron microscope annexed with energy dispersive X-ray analyser, UV-VIS spectrometer, Photoluminescence spectroscopy and a digital Keithley source meter. The X-ray diffraction investigation clearly establishes the polycrystalline nature of the films possessing orthorhombic crystal structure. The surface morphology was visualized via Field Emission Scanning Electron Microscope which confirmed the existence of spherical nano grains at 3 % Ru doping concentration. The energy dispersive X-ray analyser spectrum was used to probe the elements present in the prepared thin film and it supports the presence of Sn, S and Ru. The optical absorption and transmittance spectra were observed in the wavelength range between 450 and 900 nm for all the samples. Enhanced absorption in the visible region is observed from the absorption spectra. Direct allowed band gap values ranging around 2.05 eV–1.92 eV is observed for these Ru doped spray pyrolyzed Sn2S3 thin films. The I–V characteristics of the samples, studied under both light and dark conditions, demonstrate an increase in current values with higher concentrations of Ru doping. The highest value of the photo current (36 μA) was observed for 3 wt % ruthenium doped film. Highest responsivity of 67.6 × 10−2 A/W was observed for 3 % Ru doped Sn2S3 film. The same sample showed a highest detectivity and external quantum efficiency values of 8.70 × 109 Jones and 157 % respectively. The quick response of the detector can be affirmed from the short rise and fall time of 1.22 s and 1.21 s, respectively. Therefore, the Sn2S3 material doped with 3 % ruthenium, produced via the current economical method, emerges as a promising candidate for application in photo-detectors.

Kinetic simulations of dust grain charging in experimental plasma conditions

This paper presents fully-kinetic numerical investigations of the charging of spherical and irregular dust grains in the OML sheath regime and a stationary experimental plasma environment utilizing the Dusty Parallel Immersed-Finite-Element Particle-in-Cell (PIFE-PIC-D) framework. The simulations account for surface charging of the dust grains immersed in an stationary plasma environment. PIFE-PIC-D explicitly resolves the geometrical and material properties (permittivity) of each individual dust grain. The charge collection over time of each dust grain is investigated with varying size, irregularity, number of grains, spacing between dust grains, and permittivity. The charging behavior of a dust cluster is estimated by calculating its electron Debye length edge-to-edge separation to offer valuable insights into a dust cluster’s general charge dynamics. Lastly, unlike prior studies that focused solely on either fully conducting spheres or perfectly dielectric spheres, this work explores a more comprehensive range of permittivities for irregular dust grain aggregates.

Construction of coal fly ash-based spherical grain adsorbents and their adsorption characteristics on phenolic compounds

Addressing the significant emissions and severe pollution hazards posed by coal fly ash waste in the coal chemical industry, as well as the challenges in recovering phenolic substances from coal chemical wastewater, this study utilized coal fly ash as a raw material to construct two types of spherical grain adsorbents: coal fly ash and coal gangue spherical grain (CFAGsg) and coal fly ash and pyrite spherical grain (CFAPsg). The adsorption performance of CFAGsg and CFAPsg towards phenolic substances in coal chemical wastewater was investigated. The research results demonstrated that CFAGsg and CFAPsg exhibited adsorption capacities of 20.31 mg/L and 30.42 mg/L for phenol, respectively, and maintained stable adsorption performance even after multiple regeneration cycles. Further analysis using kinetic, isotherm, and thermodynamic models, along with various characterization techniques, revealed that the adsorption of phenol onto CFAGsg and CFAPsg was primarily governed by physical and chemical adsorption, involving an endothermic reaction. Moreover, the study on the adsorption mechanism of phenol revealed that the adsorption behavior of CFAGsg and CFAPsg was mainly driven by pore filling, π-π stacking, and hydrogen bonding. Additionally, hydrophobic interactions were involved in the adsorption of phenol onto CFAGsg, while surface complexation forces played a role in the adsorption of phenol onto CFAPsg. Overall, the research findings provide vital theoretical support and practical application prospects for the high-value utilization of coal fly ash and the clean production of the coal chemical industry.

A New Class of Multifunctional CoDyzFe2−zO4 Magnetic Nanomaterials: Influence of Structural, Morphological, Optical, Magnetic, Antibacterial, and Photocatalytic Traits

Here we focus on preparing recoverable Dy doped CoFe2O4 photocatalysts for the removal of the malachite green pollutant (MGP) in natural Sunlight. XRD results demonstrate development of the spinel symmetry with no impurities phases. The FESEM analysis revealed spherical grains with definite grain boundaries and agglomerated behavior. We found that our synthesized photocatalysts behaves as an excellent magnetic nanomaterial by observing the saturation magnetization of 77.79 emu g−1. Out of all photocatalysts, CoDy0.03Fe1.97O4 nanophotocatalyst exhibit the high zone of inhibition (ZOI) for Staphylococcus aureus and Escherichia coli. It makes the prepared nanomaterials highly suitable for the biological purposes. The effectiveness of photocatalytic degradation activity of prepared specimens is significantly impacted by the addition of dysprosium ions. During a 150 min of reaction period, CoDy0.03Fe1.97O4 has a higher degradation percentage around 95.36% as compared to CoFe2O4 (86.09%). The prepared doped and undoped CoFe2O4 nanomaterials displayed the least decline in the degradation percentage of MGP after four reuse cycles and this might be attributable to the weight loss during the recovery. Therefore, the nanomaterials suggested a reliable and durable photocatalyst for degradation process. Hence the prepared magnetically recoverable and multifunctional photocatalysts are reliable for the water remediation and biological usages.

Appraisal of the Propping Potential of Luwa Sand in Nigeria for Hydraulic Fracturing Applications

Natural sands made of spherical and round grains are widely used as proppants during hydraulic fracturing to increase recovery rate of hydrocarbon production. Synthetic proppants with high crush strength are employed for deep reservoir fracturing; however, this type of proppants suffer the disadvantages of high density, high cost and pose environmental hazards. This research was conducted with the aim to assess sands collected from Luwa River in Toro, Bauchi state of Nigeria for possible use as natural sand proppants. An epoxy resin-coated sand was produced using a simple method to modify the sands’ properties. A series of experiments were conducted in accordance with API recommended practice to determine the propping potential of the sand and the resin coated sand. The result from sieve analysis of 20/40 mesh size of Luwa sand revealed a mean size of 625.2 microns (0.625 mm). An X-ray fluorescence (XRF) result showed the presence of aluminosilicates (Al2O3 and SiO2) composition in Luwa sands. The sands recorded a hardness of 8 on the Mohs scale. Analysis of the shape parameters for sphericity and roundness was 0.8 and 0.8 (Krumbein-Sloss) respectively; it has bulk density of 1.64 g/cm3, acid solubility of 0.7% and 4.32% for the resin-coated sand. The sand has turbidity value of 28.98 NTU, loss on ignition in the range of 1.33% to 1.64% and crush resistance varies between 2000-3000 psi for Luwa sand and 4000-5000 psi for the coated sand. A comparison of the experimental results with API standard and conventional Ottawa and Brady models showed the sand competes favourably with these standards in all parameters for consideration as a proppant except for the crush resistance where more than 10% fragments was generated at low pressure of 3000 psi. However, the sand can be applied in shallow depth reservoirs.

Appraisal of the Propping Potential of Luwa Sand in Nigeria for Hydraulic Fracturing Applications

Natural sands made of spherical and round grains are widely used as proppants during hydraulic fracturing to increase recovery rate of hydrocarbon production. Synthetic proppants with high crush strength are employed for deep reservoir fracturing; however, this type of proppants suffer the disadvantages of high density, high cost and pose environmental hazards. This research was conducted with the aim to assess sands collected from Luwa River in Toro, Bauchi state of Nigeria for possible use as natural sand proppants. An epoxy resin-coated sand was produced using a simple method to modify the sands’ properties. A series of experiments were conducted in accordance with API recommended practice to determine the propping potential of the sand and the resin coated sand. The result from sieve analysis of 20/40 mesh size of Luwa sand revealed a mean size of 625.2 microns (0.625 mm). An X-ray fluorescence (XRF) result showed the presence of aluminosilicates (Al2O3 and SiO2) composition in Luwa sands. The sands recorded a hardness of 8 on the Mohs scale. Analysis of the shape parameters for sphericity and roundness was 0.8 and 0.8 (Krumbein-Sloss) respectively; it has bulk density of 1.64 g/cm3, acid solubility of 0.7% and 4.32% for the resin-coated sand. The sand has turbidity value of 28.98 NTU, loss on ignition in the range of 1.33% to 1.64% and crush resistance varies between 2000-3000 psi for Luwa sand and 4000-5000 psi for the coated sand. A comparison of the experimental results with API standard and conventional Ottawa and Brady models showed the sand competes favourably with these standards in all parameters for consideration as a proppant except for the crush resistance where more than 10% fragments was generated at low pressure of 3000 psi. However, the sand can be applied in shallow depth reservoirs.

Low-temperature catalytic methane deep oxidation over sol-gel derived mesoporous hausmannite (Mn3O4) spherical particles

In this study, Mn3O4 spherical particles (SPs) were synthesized by the sol-gel process, after which they were thermally annealed at 400 °C, and comprehensively characterized. X-ray Diffraction (XRD) revealed that Mn3O4 exhibited a tetragonal spinel structure, and Fourier transformed infrared (FTIR) spectroscopy identified surface-adsorbed functional groups. Scanning electron microscopy (SEM) and the specific surface area analyses by Brunauer−Emmett−Teller (BET) revealed a porous, homogeneous surface composed of strongly agglomerated spherical grains with an estimated average particle size of ∼35 nm, which corresponded to a large specific surface area of ∼81.5 m2/g. X-ray photoelectron spectroscopy (XPS) analysis indicated that Mn3O4 was composed of metallic cations (Mn4+, Mn3+, and Mn2+) and oxygen species (O2−, OH− and CO32−). The optical bandgap energy is ∼2.55 eV. Assessment of the catalytic performance of the Mn3O4 SPs indicated T90 conversion of CH4 to CO2 and H2O at 398 °C for gas hourly space velocity (GHSV) of 72000 mL3 g−1 h−1. This observed performance can be attributed to the cooperative effects of the smallest spherical grain size with a mesoporous structure, which is responsible for the larger specific surface area and available surface-active oxygenated species. The cooperative effect of the good reducibility, higher ratio of active species (OLat/OAds), and results of density functional theory (DFT) calculations suggested that the total oxidation of CH4 over the mesoporous Mn3O4 SPs might take place via a two-term process in which both the Langmuir−Hinshelwood and Mars−van Krevelen mechanisms are cooperatively involved.

Sol–gel derived ceramic nanoparticles as an alternative material for microstrip patch antenna in WLAN applications

In the fast-evolving realm of communication technology, microstrip patch antennas (MPAs) are in high demand owing to their compact size, lightweight, inexpensive, ease of integration, and compatibility with modern electronic devices. This research focuses on the synthesis of ZnAl2O4Ca (ZAC) ceramic nanoparticles using an economical sol–gel method suitable for microstrip patch antenna applications. The structural analysis study of ZAC nanoparticles confirmed the polycrystalline nature with 8.1 nm of crystallite size whereas an investigation of functional groups showed the corresponding vibration modes. Morphological investigation revealed the spherical grains having their mean diameter of 12.32 nm. The dielectric property’s examination, revealed the dielectric permittivity of 13, loss tangent of 0.02, and conductivity of 67 μΩ−1 cm−1. Furthermore, a prototype patch antenna fabricated using ZAC ceramics demonstrated a dual-band performance at frequencies 2.8 GHz and 4.8 GHz, with return losses of − 25.78 dB and − 28.5 dB, respectively. This work suggests the suitability of ZAC ceramic nanoparticles for use in WLAN applications.