Crystallite Size Research Articles

A General and Highly Versatile Heterogeneous Pd-Catalyzed Oxidative Aminocarbonylation of Alkynes with Aromatic and Aliphatic Amines.

An efficient heterogeneous catalytic system for the oxidative aminocarbonylation of alkynes and amines in the presence of CO/O2 to afford substituted propiolamides has been developed. The active nanocatalyst, [Pd/Mg3Al-LDH]-300(D), is composed by Pd nanoaggregates (2-3 nm average particle size) stabilized over a partially dehydrated [Mg3Al-LDH] matrix. The methodology has resulted widely applicable, being the first catalytic system, either homogeneous or heterogeneous, able to activate not only aliphatic amines but also poorly-nucleophilic aromatic amines. In fact, >60 substituted propiolamides have been synthesized in good to excellent isolated yields through this methodology, being 27 novel compounds. An important characterization effort (XRD, 27Al MAS NMR, TGA, TPD-CO2, BET area, XPS, HAADF-HRSTEM and HRTEM) and optimization of the synthesis conditions of the optimal catalyst has been performed. This study, together with a series of kinetic and mechanistic essays, indicates that the optimal catalyst is composed by Pd(0) species stabilized in a partially dehydrated/dehydroxylated LDH material with a Mg/Al molar ratio of 3 and a small crystallite size. All the experimental data indicates that the in situ formation of [PdI2] active species in the material surface together with the presence of a matrix with the optimal acid/base properties are key aspects of this process.

Mapping the microstructure and the mechanical performance of a combinatorial Co–Cr–Cu–Fe–Ni–Zn high-entropy alloy thin film processed by magnetron sputtering technique

The Co–Cr–Cu–Fe–Ni–Zn compositional library was studied on a combinatorial high-entropy alloy thin film processed on a silicon substrate by magnetron sputtering technique. The thickness of the coating was between 2 and 3 μm while the lateral dimension was 10 cm. The chemical composition in the layer depended on the location and for each constituent element the concentration varied between 5 and 42 at.%. The phase composition and the microstructure were mapped using synchrotron X-ray diffraction, and the crystallite size as well as the density of lattice defects (dislocations and twin faults) were determined by diffraction line profile profile analysis. In addition, selected locations were studied by transmission electron microscopy. The influence of the chemical composition on the microstructure and the mechanical behavior was revealed. The mechanical performance was characterized by nanoindentation mapping which determined the hardness and the elastic modulus versus the element concentrations. It was found that the coating contains single phase face-centered cubic (FCC) and body-centered cubic (BCC) regions as well as an intermediate two-phase area. In the whole combinatorial sample, the microstructure consisted of nanocrystalline columns growing perpendicular to the coating surface and having pores between them. Due to the porosity, the hardness and the elastic modulus were relatively low despite the nanostructure and the very high defect density. The highest hardness (3.4 GPa) and elastic modulus (119 GPa) were measured in the BCC region with the chemical composition of 10%Co–38%Cr–13%Cu–27%Fe–5%Ni–7%Zn (at.%).

Investigation of structural, morphological and optoelectronic properties of (Ni, Co)-doped and (Ni/Co) co-doped SnO2 (110) sprayed thin films

The manuscript details the application of spray pyrolysis for the deposition of an economically viable transparent conductive oxide film comprised of (Ni/Co) co-doped SnO2 on a glass substrate. The primary objective of this research was to systematically examine the impact of Ni/Co co-doping on diverse properties of the SnO2 thin film. These properties encompassed the film's structural composition, surface morphology, optical response, and electrical behaviors. A comparison was made with pure SnO2 film, as well as SnO2 films doped with 3 %Ni and 1 %Co. The results indicate that all the samples exhibited a tetragonal structureThe introduction of Co and Ni atoms had no impact on the favored alignment of the (110) plane or the crystal structure of the SnO2 film. The crystallite size of the pure SnO2 film, as well as the (Co, Ni)-doped and (Ni/Co) co-doped SnO2 films, varied within the range of 11 to 20 nm. Scanning electron microscopy (SEM) images were employed to assess how doping and co-doping influenced the surface characteristics of the films. The presence of pores and/or roughness on the surface resulted in a hydrophilic character and a decrease in the contact angle for the doped films (Ni, Co). However, the co-doped film exhibited a hydrophobic characteristic due to the surface enhancement provided by SnO2:3 %Ni:1 %Co. The research also focused on the optical characteristics of the films, showing a positive impact with the proper incorporation of Ni and Co atoms into the SnO2 lattice. It was notably observed that the addition of Ni and Co atoms improves the optical properties of the undoped transparent SnO2 film in the visible spectrum, with a high transmittance of 87 % achieved for the Ni-doped film. Furthermore, the hydrophobic nature achieved by adding a concentration of 3 %Ni to the SnO2:1 %Co film enhances its optical transmission in the range of 300 nm to 750 nm. The SnO2 film shows an improvement in the electrical resistivity upon doping and co-doping with low resistivity value of 2.22 × 10−2 Ω.cm for the film (3 %Ni/1 %Co)-SnO2. Drawing from these insightful results, the study proposes the potential utilization of (Ni/Co) co-doped SnO2 films as transparent electrodes in optoelectronic applications, especially in the manufacturing of thin film solar cells.

Isolation and Characterization of Spherical Cellulose Nanocrystals Extracted from the Higher Cellulose Yield of the Jenfokie Plant: Morphological, Structural, and Thermal Properties.

Scholars are looking for solutions to substitute hazardous substances in manufacturing nanocellulose from bio-sources to preserve the world's growing environmental consciousness. During the past decade, there has been a notable increase in the use of cellulose nanocrystals (CNCs) in modern science and nanotechnology advancements because of their abundance, biocompatibility, biodegradability, renewability, and superior mechanical properties. Spherical cellulose nanocrystals (J-CNCs) were successfully synthesized from Jenfokie micro-cellulose (J-MC) via sulfuric acid hydrolysis in this study. The yield (up to 58.6%) and specific surface area (up to 99.64 m2/g) of J-CNCs were measured. A field emission gun-scanning electron microscope (FEG-SEM) was used to assess the morphology of the J-MC and J-CNC samples. The spherical shape nanoparticles with a mean nano-size of 34 nm for J-CNCs were characterized using a transmission electron microscope (TEM). X-ray diffraction (XRD) was used to determine the crystallinity index and crystallinity size of J-CNCs, up to 98.4% and 6.13 nm, respectively. The chemical composition was determined using a Fourier transform infrared (FT-IR) spectroscope. Thermal characterization of thermogravimetry analysis (TGA), derivative thermogravimetry (DTG), and differential thermal analysis (DTA) was conducted to identify the thermal stability and cellulose pyrolysis behavior of both J-MC and J-CNC samples. The thermal analysis of J-CNC indicated lower thermal stability than J-MC. It was noted that J-CNC showed higher levels of crystallinity and larger crystallite sizes than J-MC, indicating a successful digestion and an improvement of the main crystalline structure of cellulose. The X-ray diffraction spectra and TEM images were utilized to establish that the nanocrystals' size was suitable. The novelty of this work is the synthesis of spherical nanocellulose with better properties, chosen with a rich source of cellulose from an affordable new plant (studied for the first time) by stepwise water-retted extraction, continuing from our previous study.

Structural Elucidation, IR spectroscopy and DC electrical conductivity of Ni0.6Zn0.4GdyFe2-yO4 nanoferrites synthesized via a low-temperature citrate gel combustion method

In the present work, we report the detailed Powder XRD Rietveld refinement and elucidation of structural factors of Ni0.6Zn0.4GdyFe2-yO4 nanoferrites. The Ni0.6Zn0.4GdyFe2-yO4 nanoferrites synthesized via low-temperature citrate gel combustion technique for the various levels of Gd3+ ion concentration (y = 0.0, 0.1, 0.15 and 0.20). The generated structural factors signify the dependence on the concentration of Gd3+ ions. The prepared samples were found to crystallize in the Fd-3m space group and also identified their occupancies; some of the Fe3+ ions of the octahedral site at the 16d position will be replaced by Gd3+ ions. The lattice constant and crystallite size dropped to a low value for y = 0.1, and then, later, noticed the small increment. The crystallite sizes of the sample are to fall in the range of 26.1 nm–37.6 nm. The cation distribution among the tetrahedral (AII) and octahedral sites (BII) has been estimated. The obtained values correlate with Gd3+ ion concentration, and the radius variation of AII and BII sites signifies the migration of Fe3+ ions from the BII site to the AII sites. The force constant of Metal-Oxygen bonds was determined from the infrared spectrographs; the force constant was found to be relatively low with the BII site. The DC electrical conductivity infers the semiconducting nature and distinct phase of conductivity, which is attributed to the magnetic phase change due to temperature. The magnetic curie temperatures of the sample are obtained by the Arrhenius plot, which signifies the dependence of Gd3+ion concentration.

Statistical approach for the preparation of silicon-graphite anodes: The role of oxygen content and crystallite size on electrochemical performance

Increasing the overall performance of Si-based anodes is still challenging because of the influence of various parameters involved in the preparation processes. This study addresses this challenge by employing the design of experiment technique to assess the impact of ball milling parameters such as milling speed, time, ball to powder and medium to powder ratio on the properties of silicon/graphite (Si/Gr) powders, with a focus on their electrochemical performance. Si/Gr powders in 20:80 weight ratio and 4 factor - 2 level full factorial design were used to find the main effects and interactions. Crystallite sizes were calculated using the Scherrer equation, and span values were obtained from the particle size distribution (PSD) analysis. SEM analyses were carried out to check the microstructure of powders. Ultimately, regression equations were created with high adjusted R2 values for crystallite size (93%), contamination (92%), and span (91%), respectively. Optimization experiments were carried out using the created regression equations, and the models were verified. It was found that crystallite size obtained by XRD data is more reliable to assess powder properties on the performance instead of PSD because of the agglomeration at the particle level throughout the milling. Further milling experiments were performed to elaborate the role of oxygen content and crystallite size. Results showed that while initial capacity is strongly related to total oxygen content, decay in the first cycles is correlated to the crystallite size of the silicon powder.

Influence of electron irradiation on the band gap and microhardness of TlInS2, TlInSSe and TlIn0.99Cr0.01S2 single crystals

ABSTRACT This work investigated the effect of partial replacement of sulphur atoms with selenium atoms (TlInSSe) and indium atoms with chromium atoms (TlIn0.99Cr0.01S2) on the band gap and microhardness of TlInS2 single crystals irradiated with electrons with energy of 2 MeV and a fluence of up to 1.5 × 1017 el/cm2. The band gap from the measured absorption spectra was determined using the Tauc method. It has been established that this irradiation leads to a decrease in the band gap in TlInS2, TlInSSe and TlIn0.99Cr0.01S2 crystals. It has been shown that after electron irradiation the microhardness of these crystals increased due to an increase in the size of crystallites on their surface.

Photocatalytic, antimicrobial and antibiofilm activities of MgFe2O4 magnetic nanoparticles

This study reports the antibacterial and antibiofilm activities of Magnesium ferrite nanoparticles (MgFe2O4) against gram-positive and gram-negative bacteria. The photocatalytic degradation of Carbol Fuchsin (CF) dye (a class of dyestuffs that are resistant to biodegradation) under the influence of UV-light irradiation is also studied. The crystalline magnesium ferrite (MgFe2O4) nanoparticles were synthesized using the co-precipitation method. The morphology of the resulting nanocomposite was examined using scanning electron microscopy (SEM), while transmission electron microscopy (TEM) was employed for further characterization of particle morphology and size. Fourier transform infrared (FTIR) spectroscopy and X-ray diffraction (XRD) were utilized to analyze the crystalline structure, chemical composition, and surface area, respectively. Optical properties were evaluated using UV–Vis spectroscopy. The UV-assisted photocatalytic performance of MgFe2O4 nanoparticles was assessed by studying the decolorization of Carbol fuchsin (CF) azo dye. The crystallite size of the MgFe2O4 nanoparticles at the (311) plane, the most prominent peak, was determined to be 28.5 nm. The photocatalytic degradation of 10 ppm CF using 15 mg of MgFe2O4 nanoparticles resulted in a significant 96% reduction after 135 min at ambient temperature (25 °C) and a pH value of 9. Additionally, MgFe2O4 nanoparticles exhibited potent antibacterial activity against E. coli and S. aureus in a dose dependent manner with maximum utilized concentration of 30 µg/ml. Specifically, MgFe2O4 nanoparticles demonstrated substantial antibacterial activity via disk diffusion and microbroth dilution tests with zones of inhibition and minimum inhibitory concentrations (MIC) for E. coli (26.0 mm, 1.25 µg/ml) and S. aureus (23.0 mm, 2.5 µg/ml), respectively. Moreover, 10.0 µg/ml of MgFe2O4 nanoparticles elicited marked percent reduction in biofilm formation by E. coli (89%) followed by S. aureus (78.5%) after treatment. In conclusion, MgFe2O4 nanoparticles demonstrated efficient dye removal capabilities along with significant antimicrobial and antibiofilm activity against gram-positive and gram-negative bacterial strains suggesting their potential as promising antimicrobial and detoxifying agents.

Sol–Gel Synthesis and Characterizations of Spinel Nickel Chromite (NiCr2O4) Nanoparticles to Study their Photocatalytic, Antibacterial and Anticancer Activities

A facile and cost-effective sol–gel technique has been used to synthesize nickel chromite (NiCr2O4) nanoparticles (NCNPs) at 700°C to investigate their photocatalytic together with antibacterial and anticancer activities. The synthesized nanopowder was characterized by Thermogravimetric thermal analysis (TG-DTA), X-ray Diffraction Spectroscopy (XRD), Field Emission Scanning Electron Microscopy (FE-SEM), High-Resolution Transmission Electron Microscopy (HR-TEM), Fourier Transform-Infrared Spectroscopy (FT-IR), X-ray Photon Electroscopy (XPS) and UV–Visible Diffuse Reflectance Spectroscopy (UV-DRS) and Photoluminescence (PL). Beyond 700°C, the thermal durability of NCNPs was confirmed by TG-DTA analysis. The synthesized NPs were cubic structured corresponding to their spinel structure, a crystallite size of 38[Formula: see text]nm and an optical bandgap of 2.7[Formula: see text]eV. The PL spectra revealed emission bands in the visible and UV regions. The surface-phase-pure elemental and electronic arrangement of the NCNPs were verified by X-ray photon spectroscopy. Photocatalytic activity of NCNPs against Methylene Blue dye revealed 89% degradation in 1[Formula: see text]h. The in vitro antibacterial and anticancer activities of NCNPs were also examined. Among the tested microbes, Staphylococcus aureus exhibited the highest level of sensitivity (9[Formula: see text]mm), while Escherichia coli had the lowest (5[Formula: see text]mm) against NCNPs. The MTT test revealed the significant cytotoxicity of NCNPs against carcinogenic HeLa and MCF-7 cells. Thus, the synthesized NCNPs could be rated as potential photocatalytic, bactericidal and anticarcinogenic agents.

Synthesis of titanium dioxide nanoparticles for enhanced photocatalytic activity in the degradation of emerging contaminants

The study investigates the impact of calcination temperature and the addition of H2O2 on the properties of TiO2 synthesized through the sol–gel method. The photoactivity of TiO2 in degrading Paracetamol revealed that the optimal calcination temperature was identified as 350 °C, attributed to a smaller crystallite size, higher surface area, and the anatase phase. Adding H2O2 during TiO2 preparation influenced the porous structure and photoactivity. Transmission electron microscopy revealed nanoparticles with average sizes of 12 ± 3 nm. TiO2 prepared with H2O2 showed improved photoactivity, possibly due to surface modifications, removing 98 % of Paracetamol. The addition of scavengers influenced the degradation efficiency, confirming the involvement of reactive species such as hydroxyl radicals. In summary, the study provides valuable insights into the influence of calcination temperature and H2O2 addition on the properties and photoactivity of TiO2, emphasizing the importance of optimal synthesis conditions for enhanced performance in environmental remediation applications.

VOCs (toluene) removal from iron ore sintering flue gas via LaBO3 (B = Cu, Fe, Cr, Mn, Co) perovskite catalysts: experiment and mechanism

Abstract The challenges posed by volatile organic compound (VOC) emissions in iron ore sintering flue gas are significant. La-based perovskite catalysts offer a promising solution for efficiently degrading VOCs. In this study, a series of LaBO3 (B = Cu, Fe, Cr, Mn, Co) perovskite catalysts were synthesized using the sol-gel method. The influence of various B-site elements on the catalyst’s structure and surface chemical properties was thoroughly examined. Simulations were conducted to assess the VOC reduction capabilities of these catalysts under conditions mimicking sintering flue gas composition. It was found that the crystallite size of the perovskite catalyst decreases as the ionic radius of the B-site elements increases, while the specific surface area, total pore volume, and average pore size increase correspondingly. Notably, LaCoO3 and LaMnO3 demonstrated exceptional activity, attributed primarily to their elevated surface oxygen concentration and oxygen migration capability, positioning them as highly promising materials for further development. Furthermore, a proposed mechanism elucidates the La-based perovskite catalytic reduction of toluene, wherein lattice oxygen and adsorbed oxygen undergo mutual conversion during the oxidation process. This mechanism aligns with the L-H and M-v-K models, providing a comprehensive understanding of the catalytic process.

Impact of Co and Cu co‐doping on the Structural, Electrical, Magnetic and Solar Light Driven Photo‐Catalytic Properties of NiFe2O4 Nano‐crystals for Crystal Violet Dye Removal

AbstractHerein, we have synthesised cobalt (Co) and copper (Cu) co‐doped Ni‐ferrite Ni1‐xCoxFe2‐yCuyO4 nanocrystals (NCs) via the facile micro‐emulsion method. The materials were analysed for various physio‐chemical characterizations to investigate the co‐doping (Co and Cu) effects on magnetic, structural, electrical, photo‐catalytic properties. The structural analysis via Fourier Transform Infrared spectroscopy (FTIR) and X‐rays diffraction (XRD) showed the successful fabrication of Co and Cu co‐doped materials with cubic spinel geometry having a single phase, the crystallite size was observed in 15 to 24 nm range. The electrical response measured using current‐voltage (I–V) analysis showed good electrical features, the electrical resistivity declined from 6.85×107 Ohm.cm for un‐doped materials to 0.04×107 Ohm.cm for co‐doped materials, which was accredited due to the synergistic effects of Co and Cu metal cations in co‐doped Ni‐based ferrite structures. Magnetic investigation using VSM analysis showed increased saturation magnetization (Ms 31.32 to 50.75 emu/g) and coercivity (218.76 to 406.82 Oe) because of the higher magnetic responses of Co2+ions in the co‐doped spinel ferrite NCs. BET surface‐area analysis showed good porosity for co‐doped materials with an increased surface area of 52 to 104 m2/g on co‐doping. The Tauc's plot described the decline of band‐gap energies value (Egs) (1.99 eV) in co‐doped (x=y=0.56) materials as compared to (2.16 eV) of the un‐doped NiFe2O4 materials, which is due to more electrical responses of Co and Cu co‐dopant cations that possess higher energy levels, which can stabilize the charge carrier‘s species. Furthermore, the photo‐degradation using solar light showed good removal of crystal violet (CV) dye, which was almost 94.14 % by co‐doped material; however, by un‐doped material, it was 38.044 %. The scavenger experiment shows that the (OH⋅) hydroxyl radicals and (e−/h+) species play a prime role in the degradation of CV dye. Recycling and recoverability tests for five cycles’ exhibited outstanding stability of the photocatalyst with only 1.7 % losses in activity. Overall, our results showed that co‐doped Ni1‐xCoxFe2‐yCuyO4 NCs materials exhibited enhancement in the magnetic, electrical, photo‐catalytic properties and a decline in band‐gap energy values as compared to un‐doped NiFe2O4, which might have potential use in magnetic and electrical devices as well as solar‐driven photo‐catalyst materials for the remediation of environmental pollution.

Enriched Surface Oxygen Vacancies of CeO2 Nanosheets: Surfactant Free Synthesis at Room Temperature and its Enhanced Anti‐bacterial Property

AbstractIn this work, flower shape cerium oxide (CeO2) nanosheets were synthesized at room temperature through a facile precipitation method without adding any surfactant. The synthesized nanosheets were characterized by scanning electron microscope (SEM), high resolution transmission electron microscope (HRTEM), Fourier transform infrared spectroscopy (FT‐IR), X‐ray diffractometry (XRD) and X‐ray photoelectron spectroscopy (XPS). Results showed that the CeO2 nanosheets form a petal‐like morphology and have fluorite crystal structure with no crystal phase impurity while the average crystallite size of nanosheets i. e. ~10 nm. The CeO2 nanosheets are applied as an antimicrobial agent and the antibacterial property against G+ and G− bacteria i. e. (E. coli and S. Aureus) were studied. The obtained results showed that the synthesized CeO2 nanosheets had good antibacterial performance at different concentrations, which should be attributed to the reversible Ce3+/Ce4+ valence states and greater oxygen vacancies. XPS study of CeO2 nanosheets after antibacterial test confirmed the existence of Ce3+ ions and oxygen vacancies. CeO2 nanosheets have showed the greater potential as antibacterial nanomaterials against both the bactericides.

The conceptual design of pH responsive ZnO-adamantane nanosystems for insulin amyloidosis

Adamantane derivatives are already being explored in amyloidogenic diseases, while ZnO nanoparticles (NPs) have the potential for affecting amyloidosis. Herein, the transformation of ZnO NPs and adamantane-1-carboxylic acid (ADA) to advanced pH responsive nanosystems is reported. Primary ZnO NPs were isolated under a simple solvothermal self-assembly synthetic procedure in the sole presence of octadecylamine (ODA). By adjusting the reaction time (8–24 h), wurtzites of crystallite sizes 19, 21 and 23 nm, respectively, were synthesized with co-crystallized ODA in monoloayer or bilayer conformation. The NPs with the bilayer of ODA have been functionalized with ADA through an amide bond, while those with the ODA monolayer were further PEGylated and ADA was loaded. Loaded ADA-ZnO nanosystems affected insulin amyloidosis in acidic pH (4.8), both in terms of final aggregation status (40 %) and by retarding the lag phase of amyloids formation. The sustained release profile of ADA was confirmed, while interaction with calf thymus DNA (CT-DNA) was evidenced by hyperchromicity. The pH of 4.8 was not enough to cleave the peptide bond, and thus the direct conjugation of ADA was effective only in prolonging the lag phase, without affecting the final amyloid formation, giving rise to the inherent properties of ZnO, foregrounding a prodrug character.

Synthesis and characterization of pristine CuO and Mg/CuO nanostructures for their anti-breast cancer and photocatalytic degradation applications: Experimental and DFT investigations

The present manuscript emphasizes the versatility of Mg-doped CuO nanostructures for environmental remediation (photocatalytic degradation of pollutants) and biomedical applications (anticancer activity) thus highlighting their potential impact in addressing societal and health challenges. The primary focus of the manuscript is the synthesis, characterization, and applications of Mg-doped CuO nanostructures. In order to meet this purpose, pure and Mg doped CuO nanostructures were synthesized using the solid-state reaction method and ball milling techniques. To characterize the prepared samples, X-ray diffraction, transmission electron microscopy, UV-Visible, photoluminescence, and Raman spectroscopy techniques were utilized. A profusion of structural defects and the reduction in crystallite size have been observed in CuO nanomaterial’s due to the dopant's complete incorporation into the CuO lattice. Additionally, the band gap of CuO has been observed to decrease as a result of Mg doping. Density functional theory was employed to simulate the effect of Mg on the properties of CuO. The efficiency of photocatalytic degradation aided by sunlight against methylene blue increased from 50.8 % to 89.5 %. MCF-7, a cell line representing human breast adenocarcinoma, was utilized to assess the cytotoxicity of Mg/CuO samples. CuO nanoparticles enriched with Mg are viable biocompatible anti-cancer agents and prospective photocatalyst for the removal of environmental pollutants from aqueous solutions, according to the findings of this study.

Evaluation of mobility range of charge carriers at microwave region in Cr substituted -CdFe2O4 ferrites

A series of chromium-substituted cadmium post-spinel ferrites CdCrxFe2-xO4 (x = 0.0, 0.1, 0.3, 0.5) have been synthesized through the sol-gel auto-ignition method. The structural, vibrational, dielectric, magnetic, and microwave absorption properties of -spinel ferrites through modern techniques which include X-ray diffraction, FTIR Spectroscopy, and Vector network analyzer. X-ray diffraction technique was used for structural investigation which confirmed the monophasic orthorhombic structure of prepared samples and a detailed study revealed that no impurity/additional phases were detected. Crystallite size and strain were extracted via the Williamson-Hall (W-H) method and Size strain plot (SSP). Vibrational spectroscopy (FTIR) successfully verified the spectral qualities of studied ferrites as measured wave number ranges between 400-600cm-1. X-ray photoelectron spectroscopy verified that all metal ions exist and possess the corresponding electronic states. Electrical properties have been investigated at the microwave region (1MHz – 6GHz). The conduction mechanism has been studied via Johnscher power law. The Cole-Cole plot of all the samples consisting of two semicircles corresponding to grain and grain boundaries described the increasing conduction phenomena. In the present research, stable dielectric constant, dielectric loss, enhanced magnetic characteristics, and minimum reflection loss (-31.9 dB) make these CdCrxFe2-xO4 nano-crystallites most suitable candidates for highly dense and high-frequency microwave devices for EMI shielding material.

The effects of processing technique on formation temperature of calcium aluminate magnesium (CaO.2MgO.8Al2O3)

This study aims at the synthesis of a ternary phase crystal CaO.2MgO.8Al2O3 (CM2A8) in the Al-rich part of the ternary system CaO-Al2O3-MgO through two techniques: (1) sol–gel citrate and (2) solid-state reaction. Based on the measurement of particle size, density, phase analysis, nature of bounds, and microscopic observation, the effect of the processing technique on the crystal purity, crystallite size, and synthesis temperature of the as-prepared CM2A8 powder was investigated. Phases analysis (XRD patterns) showed in the sol–gel citrate combustion method almost a single-phase material (calcium aluminate magnesium phases) at relatively lower temperatures while in the solid-state method as-prepared CM2A8 powder with a small amount of spinel (MgAl2O4 = MA) and calcium hexaaluminate (CaAl12O19 = CA6) secondary phases. The generated heat through the combustion of the reaction of ammonium nitrate and citrate-based complexes decreases the synthesis temperature of nanocrystalline CM2A8, and the CM2A8 phase is formed at a temperature of 1400 °C. While growth mechanism in the solid-state reaction method adheres to the two-dimensional nucleation theory and a thick hexagonal flake known as CM2A8 is produced at a temperature of 1700 °C. In comparison with the crystals synthesized by the solid-state reaction method, the powder density of the nanocrystals synthesized by a sol–gel combustion method exhibits higher values (3.54 g.cm−3 and 3.65 g.cm−3, respectively). Peak intensities in the 400–1000 cm−1 range, according to FTIR measurements, correspond to metal–oxygen–metal (M–O–M) bonds (vibrations of Al–O stretching in Mg–O–Al and Ca–O–Al), and they grow as the temperature rises from 200 °C to 1400 °C, indicating that CM2A8 was the crystal that was formed. The morphological analysis (FESEM) revealed that most of the agglomerate particles synthesized by the sol–gel citrate combustion remained within the range of 50–83 nm, while the particles synthesized by the had particles as 1 μm. The specific surface area synthesized CM2A8 via the sol–gel method is in the range of 10–24 m2/g. The main advantages of the sol–gel citrate process are the high purity of the product, the narrow particle size distribution, and the achievement of uniform nanostructure at low temperatures.

Electrochemical, Magnetic and heterostructure of Y-SnO2-CdO nanocomposite for multi-functional applications

We prepared the novel materials of Y- doped SnO2-CdO nanocomposite, Y-SnO2 and CdO nanoparticles by facile chemical technique. Structural, crystalline size and lattice parameters are studied by XRD spectrometer. The morphologies show highly aggregated due to tiny particles of Y3+, Sn4+ and Cd2+ were present in nanocomposite were analyzed by HR-TEM. The presence of a functional group of elements was identified by FT – IR spectrometer. Using X-ray photoelectron spectroscopy (XPS) to analyze the ionization state of elements and purity of nanocomposite. Optical properties such as lower absorption edge, widened band gap and lower crystalline size were studied by UV – visible spectrometer and Photo luminescence (PL) was used to determine the violet emission of nanocomposite. At room temperature, ferromagnetism was obtained in the nanocomposite was studied by VSM. From Cyclic-Voltammetry (CV), the nanocomposite has constant pseudo capacitance that occurs in the potential range between – 0.7V to 0.5V. Electrochemical impedance spectroscopy (EIS) was investigated for impedance, dielectric, electric modules and a.c conductivity of nanocomposite. Hence, based on the optical, magnetic and electrochemical properties of Y-SnO2-CdO nanocomposite is highly suitable for multi-functional potential applications.

Tailoring barrier layers design for haute couture through X-ray microanalysis: Insights and guidelines

Barrier layers against intermetallic diffusion are a fundamental part on engineering electroplated coatings as they improve the lifetime of goods reducing wastes and improving the sustainability of the production chain. This study aims to set a cost-effective methodology to characterize barrier systems by evaluating the effectiveness with a recent approach based on XRF and EDS and characterize the kinetic of diffusion processes with X-ray diffractometry. Several high fashion barrier systems were tested highlighting that anticorrosion systems are not automatically suited as barrier layers for intermetallic diffusion, as opposed to industrial practice. Investigations on gold coatings obtained varying the current density revealed a correlation between the activation energy of the diffusion process, roughness, and crystallite size.

An investigation for optical, photocatalytic, photoluminescence and dielectric properties of Cd0.40Ni0.60ZnO2 annealed nanocomposites

We report here the optical, photoluminescence (PL), and dielectric properties of Cd0.40Ni0.60ZnO2 nanocomposites annealed between 200 and 600oC. An increase in annealing temperature (Tann) up to 600oC correlates with a gradual increase in the crystallite and particle sizes. The surface area, pore radius, and pore volume are increased as Tann increases from 200oC to 300oC, and then decreased, but still higher than of 200oC. Similar behaviors were obtained for the absorbance carrier density, photocatlytic efficiency, degradation rate, PL intensity, dielectric constant, dielectric loss, ac conductivity, F-factor, series resistance, and electronic polarizability. While the energy gap, binding energy, impedance of grains and their boundaries, and effective capacitance show an opposite behavior. The relaxation times at the peak of dielectric parameters are between 11.54 and 159.24ns and between 35.23 and 24273.73ns, respectively. The Cole-Cole plot shows a single semicircle at Tann < 400oC and two successive semicircles at Tann> 500oC. The energy of PL of visible emissions is independent on the chosen Tann. These findings indicated that the nanocomposite annealed at 300oC can be used for water purification, telecommunications, solar cells, supercapacitor, and white light-emitting diodes (LEDs).