Stem Research Articles

Weak Spots in Semiconductor Nanoplatelets: From Isolated Defects Toward Directed Nanoscale Assemblies.

The chemical engineering of nanostructures with atomic-scale precision is a fundamental scientific challenge. Cation exchange reactions in nanoplatelets (NPLs) offer an attractive platform for this precision chemistry, as it is relatively simple to carry out, extremely versatile, and allows the production of heterogeneous nanostructures that cannot be produced by any other means. A major hindrance has, however, been the lack of knowledge of the "weak spots" of the platelets where the ionic exchange reaction is initiated to optimally control the process toward directed nanoscale assemblies. Here, mercury selenide formation in cadmium selenide NPLs is investigated. The study of Cd(1-n)HgnSe NPLs using scanning transmission electron microscopy (STEM) pinpoints at the corners (vertices) and edges of the NPLs as the exchanged sites. Comprehensive first principles density functional calculations of Hg substitution energies in a hierarchy of models of four monolayers (ML) CdSe NPL stabilized with acetate ligands unambiguously underscore that the energetically preferred exchange positions are platelet corners - in line with the experimental findings. The results thus not only explain in detail how the cation exchange process in 2D CdSe NPLs is kicked-off, but also establish an arena for future studies in 2D nanomaterials reaching far beyond these reactions.

Integrating Experimental and Computational Insights: A Dual Approach to Ba2CoWO6 Double Perovskites

Double perovskite materials have emerged as key players in the realm of advanced materials due to their unique structural and functional properties. This research mainly focuses on the synthesis and comprehensive characterization of Ba2CoWO6 double perovskite nanopowders utilizing a high-temperature conventional solid-state reaction technique. The successful formation of Ba2CoWO6 powders was confirmed through detailed analysis employing advanced characterization techniques. Rietveld refinement of X-ray diffraction (XRD) and Raman data established that Ba2CoWO6 crystallizes in a cubic crystal structure with the space group Fm-3m, indicative of a highly ordered perovskite lattice. The typical crystallite size, approximately 65 nm, highlights the nanocrystalline nature of the material. Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM) discovered a distinctive morphology characterized by spherical shaped particles, suggesting a complex particle formation process influenced by synthesis conditions. To probe the electronic structure, X-ray Photoelectron Spectroscopy (XPS) identified cobalt and tungsten valence states, critical for understanding dielectric properties associated with localized charge carriers. The semiconducting character of the synthesized Ba2CoWO6 nanocrystalline material was confirmed through UV-Visible analysis, which revealed an energy bandgap value of 3.3 eV, which aligns well with the theoretical predictions, indicating the accuracy and reliability of the experimental results. The photoluminescence spectrum exhibited two distinct emissions in the blue-green region. These emissions were attributed to the transitions 3P0→3H4, 3P0→3H5, and 3P0→3H6, primarily resulting from the contributions of Ba2+ ions. The dielectric characteristics of the compound were analyzed across a different range of frequencies, spanning from 1 kHz to 1 MHz. Magnetic characterization using Vibrating Sample Magnetometry (VSM) revealed antiferromagnetic behavior of Ba2CoWO6 ceramics at room temperature, attributed to super-exchange interactions between Co3+ and W5+ ions mediated by oxygen ions in the perovskite lattice. Additionally, first-principles calculations based on the Generalized Gradient Approximation (GGA+U) with a modified Becke–Johnson (mBJ) potential were employed to gain a deeper understanding of the structural and electronic properties of the materials. This approach involved systematically varying the Hubbard U parameter to optimize the description of electron correlation effects. These results deliver an extensive understanding of the structural, optical, morphological, electronic, and magnetic properties of Ba2CoWO6 ceramics, underscoring their potential for electronic and magnetic device applications.

Covalent integration of polymers and porous organic frameworks

Covalent integration of polymers and porous organic frameworks (POFs), including metal-organic frameworks (MOFs), covalent organic frameworks (COFs) and hydrogen-bonded organic frameworks (HOFs), represent a promising strategy for overcoming the existing limitations of traditional porous materials. This integration allows for the combination of the advantages of polymers, i.e., flexibility, processability and chemical versatility etc., and the superiority of POFs, like the structural integrity, tunable porosity and the high surface area, creating a type of hybrid materials. These resulting polymer-POF hybrid materials exhibit enhanced mechanical strength, chemical stability and functional diversity, thus opening up new opportunities for applications across a large variety of fields, such as gas separation, catalysis, biomedical applications, environmental remediation and energy storage. In this review, an overview of synthetic routes and strategies on how to covalently integrate different polymers with various POFs is discussed, especially with a particular focus on methods like polymerization within, on and among POF structures. To investigate the unique properties and functions of these resultant hybrid materials, the characterization techniques, including nuclear magnetic resonance spectroscopy (NMR), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), thermogravimetric analysis (TGA), transmission electron microscopy (TEM) and scanning electron microscopy (SEM), gas adsorption analysis (BET) and computational modeling and machine learning, are also presented. The ability of polymer-POFs to manipulate the pore environments at the molecular level affords these materials a wide range of applications, providing a versatile platform for future advancements in material science. Looking forward, to fully realize the potential of these hybrid materials, the authors highlight the scalability, green synthesis methods, and potential for stimuli-responsive polymer-POF materials as critical areas for future research.

Stable Fabrication of Chitosan/Polycaprolactone (CS/PCL) Core-Shell Nanofibers by Electrospinning

Chitosan (CS), with its non-toxic and antibacterial properties, and Poly(ε-caprolactone) (PCL), known for its biodegradability and biocompatibility, are crucial materials in medical applications. This study proposed a solution utilizing electrospinning to manufacture fibers with nanometer-sized core-shell structures from these materials, with CS serving as the fiber core and PCL forming the shell. The influence of manufacturing technology parameters on fiber size and morphology was thoroughly researched and investigated. The solvent system used, Chloroform/Dimethylformamide (DMF), ensured complete solubility, viscosity control, conductivity, and proper solvent evaporation. Transmission Electron Microscopy (TEM) and Scanning Electron Microscopy (SEM) results clearly demonstrated the morphology and internal structure of the nanofibers. The water contact angle (WCA) measurements of the fiber membrane showed almost no significant change over time, indicating strong hydrophobicity of the nanofibers. Additionally, the FTIR spectrum revealed distinct core-shell layers without any blending between them, while DSC analysis showed the thermal properties of fiber membranes. In summary, the electrospinning of nanofibers proved to be stable, producing thin fibers with an average diameter of approximately 400 nm. These findings are expected to significantly enhance the applicability of CS/PCL nanofibers across various fields, including healthcare and smart agriculture.

Local chemical heterogeneity enabled superior zero thermal expansion in nonstoichiometric pyrochlore magnets

Abstract Design of zero thermal expansion (ZTE) materials is urgently required as dimension stable component in widespread modern high-precision technologies. Local chemical order has been of great importance in engineering advanced inorganic materials, but its role in optimizing the ZTE is often overlooked. Herein, we propose local composition heterogeneity for developing superior ZTE via a nonstoichiometric strategy. A remarkably low coefficient of thermal expansion of αa = +1.07 × 10−6 K−1 is achieved from 3 to 440 K in a quaternary Zr-Nb-Fe-Co pyrochlore magnet, which is the widest temperature range among known cubic ZTE metals. High-resolution synchrotron X-ray diffraction and magnetisation measurements reveal that all the Bragg peaks split as resulting from two cubic phases with different magnetic orders. Scanning transmission electron microscopy, Mössbauer spectroscopy and theoretical calculations indicate that such phase separation intimately derive from excess Co dopant preferentially clustering on the Fe pyrochlore-lattice (16d) and simultaneously yielding an antisite Fe on Zr/Nb sublattice (8a). The Co content in pyrochlore-lattice has weaker exchange interactions than that of Fe, but the antisite Fe introduces extra positive exchange interactions between 8a-16d site. Local composition fluctuation of Co and Fe thus affects interplanar ferromagnetic order of pyrochlore-lattice and balances the normal phonon effect successively on heating. Superior corrosion resistance to both acid and alkaline conditions merits potential applications of the present ZTE metal.

Optical and Electrochemical Analysis of Surface‐Enhanced ZnZrO3:Eu3+ Nanostructures for Forensic Applications

AbstractThe surface‐enhanced local crystal structure of a series of ZnZrO3:Eu3+(1 to 5 mol.%) (ZZE) orange–red nanophosphors synthesized using a sol‐gel combustion process is investigated. X‐ray diffraction (XRD) with the Rietveld refinement analysis reveals a monoclinic ZnZrO3:Eu3+ structure with a space group 14. Field emission scanning electron microscope (FESEM) and transmission electron microscope (TEM) analyses reveal the honeycomb alignment of nanoparticles in structure formation. The UV–vis‐diffuse reflectance spectroscopy (UV–vis‐DRS) analysis reveals strong absorption in the UV region, with an increase in the energy bandgap upon the addition of Eu3+ ions (1 to 5 mol.%). The optimized ZnZrO3:Eu3+(2 mol.%) nanophosphor exhibits high‐intensity orange‐red emission at 615 nm, as revealed by photoluminescence (PL) spectroscopy. Cyclic voltammetry (CV) analysis confirms the surface‐modified ZnZrO3:Eu3+ (2 mol.%) nanophosphor and hence reveals its electrochemical stability and selectivity to form stable suspensions with liquids or solids. ZnZrO3:Eu3+ (1 to 5 mol.%) exhibits fluorophore (Eu3+) embedded, surface‐enhanced Raman scattering, which opens new bioimaging applications. Further, the optimized ZnZrO3:Eu3+ (2 mol.%) nanophosphor investigated for the identification of latent fingerprint patterns (LFP) under visible light indicates its potential as a strong LFP‐revealing material in forensics without alternate light sources or chemical reagents.

Tutorial on In Situ and Operando (Scanning) Transmission Electron Microscopy for Analysis of Nanoscale Structure-Property Relationships.

In situ and operando (scanning) transmission electron microscopy [(S)TEM] is a powerful characterization technique that uses imaging, diffraction, and spectroscopy to gain nano-to-atomic scale insights into the structure-property relationships in materials. This technique is both customizable and complex because many factors impact the ability to collect structural, compositional, and bonding information from a sample during environmental exposure or under application of an external stimulus. In the past two decades, in situ and operando (S)TEM methods have diversified and grown to encompass additional capabilities, higher degrees of precision, dynamic tracking abilities, enhanced reproducibility, and improved analytical tools. Much of this growth has been shared through the community and within commercialized products that enable rapid adoption and training in this approach. This tutorial aims to serve as a guide for students, collaborators, and nonspecialists to learn the important factors that impact the success of in situ and operando (S)TEM experiments and assess the value of the results obtained. As this is not a step-by-step guide, readers are encouraged to seek out the many comprehensive resources available for gaining a deeper understanding of in situ and operando (S)TEM methods, property measurements, data acquisition, reproducibility, and data analytics.

Unveiling and mapping polymorphs in fluorite Y2TiO5 using 4D‐STEM and unsupervised machine learning

AbstractY2TiO5 belongs to the Ln2TiO5 (Ln = lanthanide or Y) family of ceramic materials and exhibits a range of desirable material properties such as radiation tolerance, frustrated magnetism, and large dielectric constant. However, understanding the complex crystal structure of Y2TiO5 remains elusive, given that Y2TiO5 can adopt multiple polymorphs such as cubic, orthorhombic, and hexagonal phases within the lattice. In this work, we report a detailed structural analysis of Y2TiO5 using four‐dimensional scanning transmission electron microscopy coupled with unsupervised machine learning. The pyrochlore nanodomains, characterized by the ordered arrangement of yttrium cations on the A site of their A2BO5 structure, are present within the matrix of a predominantly fluorite‐structured Y2TiO5 along with a third polymorph, the hexagonal phase. The pyrochlore phase is found to form 2 nm boundary regions around hexagonal phase stacking faults, highlighting the potential influence of the hexagonal phase on the occurrence and distribution of the pyrochlore phase. Lastly, we identify a unique pyrochlore phase with asymmetric arrangement of cation ordering along a single planar direction. Our findings provide invaluable insights into the possible mechanisms stabilizing pyrochlore nanodomains within the fluorite lattice of Y2TiO5.

GeTe/Sb2Te3 Super‐Lattices: Impact of Atomic Structure on the RESET Current of Phase‐Change Memory Devices

AbstractPhase change memories (PCMs) are at the heart of modern memory technology, offering multi‐level storage, fast read/write operations, and non‐volatility, bridging the gap between volatile DRAM and non‐volatile Flash. The reversible transition between amorphous and crystalline states of phase‐change materials such as GeTe or Ge2Sb2Te5 is at the basis of PCM devices. Despite their importance, PCM devices face challenges including high power consumption during the RESET operation. Current research efforts focus on improving device architecture and exploring alternative phase‐change materials such as GeTe/Sb2Te3 super‐lattices (SLs), for which a reduced programming power consumption is observed compared with standard PCMs. Herein, by combining X‐ray diffraction and scanning transmission electron microscopy imaging of SL thin films with the study of the same SL in PCM devices, it is shown that it is possible to significantly decrease RESET energy of the device, without modifying the SL composition, by reducing the amount of structural defects through annealing treatment. The best device properties are obtained after transforming the SL into a defect‐free, highly out‐of‐plane oriented rhombohedral phase. These results offer a promising avenue for further improving the performance of SL‐based PCM devices through structural optimization.

Green Synthesized Composite AB-Polybenzimidazole/TiO2 Membranes with Photocatalytic and Antibacterial Activity

Novel AB-Polybenzimidazole (AB-PBI)/TiO2 nanocomposite membranes have been prepared using a synthetic green chemistry approach. Modified Eaton’s reagent (methansulfonic acid/P2O5) was used as both reaction media for microwave-assisted synthesis of AB-PBI and as an efficient dispersant of partially agglomerated titanium dioxide powders. Composite membranes of 80 µm thickness have been prepared by a film casting approach involving subsequent anti-solvent inversion in order to obtain porous composite membranes possessing high sorption capacity. The maximal TiO2 filler content achieved was 20 wt.% TiO2 nanoparticles (NPs). Titania particles were green synthesized (using a different content of Mentha Spicata (MS) aqueous extract) by hydrothermal activation (150 °C), followed by thermal treatment at 400 °C. The various methods such as powder X-ray diffraction and Thermogravimetric analyses, X-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy and Energy-dispersive X-ray spectroscopy, Electronic paramagnetic resonance, Scanning Electron Microscopy and Transmission Electron Microscopy have been used to study the phase and surface composition, structure, morphology, and thermal behavior of the synthesized nanocomposite membranes. The photocatalytic ability of the so-prepared AB-Polybenzimidazole/bio-TiO2 membranes was studied for decolorization of Reactive Black 5 (RB5) as a model azo dye pollutant under UV light illumination. The polymer membrane in basic form, containing TiO2 particles, was obtained with a 40 mL quantity of the MS extract, exhibiting the highest decolorization rate (96%) after 180 min of UV irradiation. The so-prepared AB-Polybenzimidazole/TiO2 samples have a powerful antibacterial effect on E. coli when irradiated by UV light.

Localized Boron Sites in Large Pore Borosilicate Zeolite EMM-59 Determined by Electron Crystallography.

The structure of novel large pore borosilicate zeolite EMM-59 (|C19H42N2|8[B5.2Si218.8O448]) with localized framework boron sites was determined by using three-dimensional electron diffraction (3D ED) and scanning transmission electron microscopy (STEM) imaging. EMM-59 was synthesized using 2,2-(cyclopentane-1,1-diyl)bis(N,N-diethyl-N-methylethan-1-aminium) as an organic structure-directing agent (OSDA). The framework has a three-dimensional intersecting channel system delimited by 12 × 10 × 10-ring openings and contains 28 T and 60 oxygen atoms in the asymmetric unit, making it the most complex monoclinic zeolite. The 3D ED data collected from as-made EMM-59 under cryogenic conditions revealed three symmetry-independent locations of the OSDAs, and STEM imaging showed that the OSDAs are flexible and adopt different molecular conformations in channels with identical structural environments. The framework boron atoms were exclusively found in T-sites of 4-rings, especially those shared by multiple 4-rings. The tetrahedral BO4 with the highest boron content (38.6%) was transformed into a trigonal BO3 after the OSDAs were removed upon calcination. Its location and boron content could also be identified by STEM imaging.

Local Hydrogen Concentration and Distribution in Pd Nanoparticles: An In Situ STEM-EELS Approach.

Local detection of hydrogen concentration in metals is of central importance for many areas of hydrogen technology, such as hydrogen storage, detection, catalysis, and hydrogen embrittlement. A novel approach to measure the hydrogen concentration in a model system consisting of cubic palladium nanoparticles (Pd NPs), with a lateral resolution down to 4nm is demonstrated. By measuring the shift of the Pd bulk plasmon peak with scanning transmission electron microscopy (STEM) combined with energy electron loss spectroscopy (EELS) during in situ hydrogen gas loading and unloading, local detection of the hydrogen concentration is achieved in TEM. With this method, concentration changes inside the NPs at various stages of hydrogenation/dehydrogenation are observed with nanometer resolution. The versatility of in situ TEM allows to link together microstructure, hydrogen concentration, and local strain, opening up a new chapter in hydrogen research.

Crystal and Electronic Structure of β‐Nb2N Thin Films Grown by Molecular Beam Epitaxy

AbstractNiobium nitrides have garnered significant research interest since their discovery due to their exceptional properties and broad applications. In this study, NbNx thin films are successfully grown on 4H(6H)‐SiC(001) substrates using nitrogen‐assisted molecular beam epitaxy. Through scanning transmission electron microscopy and X‐ray diffraction, it is confirmed that the crystal structure of the thin films corresponds to the β‐Nb2N. Different from the previously reported structure of the βA phase (P63/mmc) of β‐Nb2N, the results clearly match with the βB phase (). Resistivity measurements reveal that β‐Nb2N exhibits superconductivity at ≈10 K with an upper critical field of ≈5 T. Its 3D electronic structure is further elucidated using angle‐resolved photoemission spectroscopy combined with theoretical calculations. The observed superconductivity in β‐Nb2N is attributed to its relatively high electron–phonon coupling strength and density of states at Fermi level. Interestingly, it is found that the sample is close to a Lifshitz transition, suggesting potential for tunable physical properties. The results provide a comprehensive understanding of the crystal and electronic structures of β‐Nb2N, facilitating its future applications.

Irreversible Lattice Expansion Effects in Nanoscale Indium Oxide for CO2 Hydrogenation Catalysis.

Thermal energy has been considered the exclusive driving force in thermochemical catalysis, yet associated lattice expansion effects have been overlooked. To shed new light on this issue, variable temperature in situ high-resolution (scanning) transmission electron microscopy (HR-(S)TEM) and electron energy-loss spectroscopy (EELS) were employed to provide detailed information on the structural changes of an archetype nanoscale indium oxide materials and how these effects are manifest in reverse water gas shift heterogeneous catalytic reactivity. It is found that with increasing temperature and vacuum conditions, an irreversible surface lattice expansion is traced to the formation and migration of oxygen vacancies. Together, these changes are believed to be responsible for the decreased activation energy and improved reaction rate observed for the reverse water gas shift reaction. Studies of this kind provide new insight into how thermal energy affects thermochemical heterogeneous catalysis.

Passivating oxidation behavior of Ti0.12Al0.21B0.67 coatings investigated by scanning transmission electron microscopy and chemical environment dependent density functional theory simulations

Passivating oxidation behavior of Ti0.12Al0.21B0.67 coatings investigated by scanning transmission electron microscopy and chemical environment dependent density functional theory simulations

Indium-flush technique for C-band InAs/InP quantum dots

High-quality InAs/InP quantum dots (QDs) emitting at 1550 nm are indispensable to realize high-performance telecom C-band lasers. In general, a longer emission (>1550 nm) with a broad spectral character has been obtained with InAs/InP QDs. Here, we proposed the use of the indium-flush (IF) method to shorten the emission and improve the optical properties of InAs/InP QDs. By exploiting IF, the full-width at half-maximum of the room-temperature QD photoluminescence spectra is narrowed from 89.2 to 47.9 meV, with a blue shift of 300 nm (from 1824 to 1522 nm). The scanning transmission electron microscopy and electron energy loss spectroscopy results reveal the atomic-level mechanism of the IF method, which uniformly modify the height of InAs/InP QDs in a controlled manner and form distinct Al-rich and In-rich regions. Finally, InAs/InP (001) QD lasers with the IF method have been demonstrated with a low threshold current density per QD layer of 106 A/cm2. We demonstrated both in terms of mechanism model and device performance that the IF method could serve as a robust strategy for the growth of high-performance C-band InAs/InP QD lasers via molecular beam epitaxy.

On the effect of precession for magnetic differential phase contrast imaging

The separation of diffraction effects from phase contrast is a major challenge for differential phase contrast (DPC) imaging in scanning transmission electron microscopy (STEM). The application of electron beam precession has previously been proven successful in homogenizing the direct beam and improving the imaging of both long-range electric and magnetic fields. However, magnetic STEM-DPC imaging performed in a low magnification (LM) STEM mode suffers from significant aberrations of the probe forming lens and the consequent impediment of small precession angles. By investigating the application of precession path segmentation to LM-STEM precessed scans for the imaging of LSMO and FeAl thin film samples, the initially reported benefits of precession were discovered to be less substantial than originally assumed. The segmentation methodology reveals that precession induced beam phase shifts account for a large part of the DPC induction profile smoothing, and the precession path is non-circular, leading to streaking artifacts in the reconstructed induction maps.

Assessing the dual toxicity of HfO2 nanoparticles and quinalphos on Pila virens

Pila virens (P. virens) is an edible freshwater snail, widely distributed in Asia and Africa. P. virens is used as one of the most promising model organisms for monitoring environmental contamination in aquatic ecosystems. The physiological responses to the contaminants such as pesticides and nanomaterials are inadequate, especially in relation to the effects of co-exposure. In this work, we have investigated on the noxious effects of co-exposure between an organophosphorus pesticide, quinalphos and hafnium oxide nanoparticles (HfO2NPs) on the antioxidant responses of P. virens. Phase pure forms of HfO2NPs (monoclinic, P21/c) were obtained by sol-gel method. The crystallinity, structure and surface morphology were analysed with various spectroscopic methods like powder X-ray, Fourier-transform infrared spectroscopy (FT-IR), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), High Resolution Scanning Electron Microscope (HR-SEM) and Transmission Electron Microscope (TEM). P. virens after exposure for 96 h to the different concentrations of quinalphos (0.25–2.25 mg/mL) and HfO2NPs (10–50 mg/mL), the median lethal concentration (LC50) was determined to be 1.159 mg/mL and 11.47 mg/mL, respectively and show a significant fatal effect against the snail. The P. virens were exposed to sub-lethal concentrations of LC25 (0.57 mg/mL quinalphos and 5.73 mg/mL HfO2NPs) individually and in combination as a binary toxicity (quinalphos + HfO2NPs), (0.57 mg/mL + 5.73 mg/mL) for 24 and 48 h. Further, the antioxidant responses were assessed which included catalase (CAT), glutathione sulfo-transferase (GST), and malonaldehyde (MDA) activity in the group exposed to quinalphos and HfO2NPs exhibited to show an enhancement in their activity in comparison to controls after 24 and 48 h and revealed that 48 h exposure has significant impact. These results provide a valuable insight towards increased awareness of the physiological defences of P. virens after co-exposure to quinalphos and HfO2NPs in aquatic ecosystem.

Direct observation of the evolution behavior of micro to nanoscale precipitates in austenitic heat-resistant steel via electron channeling contrast imaging

Precipitation directly determines the high-temperature properties of the austenitic heat-resistant steels. The precipitations of MX, Z-phase, M23C6 and σ-phase, ranging from micrometers to nanometers, are commonly characterized using the scanning electron microscopy (SEM) and transmission electron microscopy (TEM). However, details of their evolution behavior are still unclear due to the limited SEM resolution using the traditional sampling method and the limited spatial resolution of TEM. In this work, field emission SEM-based electron channel contrast imaging (ECCI) techniques with flexible sampling routes were introduced to observe the precipitation evolution behavior of HR3C steel after aging at 700 °C for 8095 h. We showed that the coarse primary-MX and Z-phase in the as-received steel are relatively stable during aging. The coarse M23C6 and tiny secondary Z-phase dispersions were rapidly formed along the grain/twin boundaries and within dislocation arrays inside the grain interior, respectively. We further found that the M23C6 at grain boundaries would change from continuous to semi-continuous due to the formation of σ-phases, while in twin boundaries, it would become continuous over aging. Moreover, we showed that the σ-phases were in-situ transformed from M23C6 at the grain boundaries via its dissolution, facilitating the nucleation of tiny Z-phase inside the σ-phase grains, and this phenomenon has not been reported so far. We have demonstrated that ECCI with an electrolytic-polishing-based sampling route is effective in revealing multi-scale precipitation with high-throughput efficiency, and it allows the direct observation of the complex behavior of precipitates down to the nanoscale using a bulk sample. This method can be used as an efficient way for the quantitative microstructure study.

Enhanced Photocatalytic Degradation of Reactive Dyes Under Visible Light Using ZnO/CdS/Co Nanocomposites: A Step Toward Advanced Environmental Remediation.

In this study, ZnO, CdS, ZnO/CdS, and ZnO/CdS/Co nanostructures were successfully synthesized using a simple chemical precipitation method. The formation of these nanostructures was confirmed through x-ray diffraction (XRD), but their morphological properties were analyzed using scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Their optical properties were investigated using UV-visible diffuse reflectance spectroscopy (UV-DRS) and photoluminescence spectroscopy (PL). The photocatalytic activity of these materials was tested for the degradation of Reactive Blue 160 (RB 160) under visible light. It was observed that ZnO/CdS nanocomposites exhibited superior photocatalytic performance compared to pure ZnO. Furthermore, the inclusion of cobalt (Co) in the ZnO/CdS nanocomposites significantly enhanced this activity, likely due to improved visible light absorption. These findings suggest that ZnO/CdS/Co nanocomposites are promising candidates for efficient photocatalytic applications, particularly in environmental remediation under visible light.