Selected Area Electron Diffraction Research Articles

The influence of neutral MDP-Na salt on dentin bond performance and remineralization potential of etch-&-rinse adhesive

ObjectivesTo investigate the effect of neutral 10-methacryloyloxydecyl dihydrogen phosphate salt (MDP-Na) on the dentin bond strength and remineralization potential of etch-&-rinse adhesive.MethodsTwo experimental etch-&-rinse adhesives were formulated by incorporating 0 wt% (E0) or 20 wt% (E20) neutral MDP-Na into a basic primer. A commercial adhesive, Adper Single Bond 2 (SB, 3 M ESPE), served as the control. Sixty prepared teeth were randomly allocated into three groups (n = 20) and bonded using either one of the experimental adhesives or SB. Following 24 h of water storage, the bonded specimens were sectioned into resin-dentin sticks, with four resin-dentin sticks obtained from each tooth for microtensile bond strength (MTBS) test. Half of the sticks from each group were immediately subjected to tensile loading using a microtensile tester at a crosshead speed of 1 mm/min, while the other half underwent tensile loading after 6-month incubation in artificial saliva (AS). The degree of conversion (DC) of both the control and experimental adhesives (n = 6 in each group) and the adsorption properties of MDP-Na on the dentin organic matrix (n = 5 in each group) were determined using Fourier-transform infrared spectrometry. Furthermore, the effectiveness of neutral MDP-Na in promoting the mineralization of two-dimensional collagen fibrils and the adhesive-dentin interface was explored using transmission electron microscopy and selected-area electron diffraction. Two- and one-way ANOVA was employed to assess the impact of adhesive type and water storage on dentin bond strength and the DC (α = 0.05).ResultsThe addition of MDP-Na into the primer increased both the short- and long-term MTBS of the experimental adhesives (p = 0.00). No difference was noted in the DC between the control, E0 and E20 groups (p = 0.366). The MDP-Na remained absorbed on the demineralized dentin even after thorough rinsing. The intra- and extra-fibrillar mineralization of the two-dimensional collagen fibril and dentin bond hybrid layer was confirmed by transmission electron microscopy and selected-area electron diffraction when the primer was added with MDP-Na.ConclusionsThe use of neutral MDP-Na results in high-quality hybrid layer that increase the dentin bond strength of etch-&-rinse adhesive and provides the adhesive with remineralizing capability. This approach may represent a suitable bonding strategy for improving the dentin bond strength and durability of etch-&-rinse adhesive.

Near-Zero Temperature Coefficient of Resonance Frequency in Rare-Earth Titanates via the Phase Transition Strategy.

This study presents an approach to achieve a near-zero temperature coefficient of resonance frequency (τf) in rare-earth titanate microwave dielectric ceramics (MWDCs) by inducing a phase transition. By Zr4+ substitution at the B site, a series of Sm2Ti1-xZrxO5 (0.02 ≤ x ≤ 0.55) ceramics are synthesized using the solid-state method to intentionally alter the radius ratio of the A/B sites, realizing in a controlled phase transition from orthorhombic (Pnma) to biphasic coexistence and ultimately to cubic (Fd3̅m) structure. The phase composition is rigorously identified through X-ray diffraction (XRD) Rietveld refinement, high-resolution transmission electron microscopy (HRTEM), selected-area electron diffraction (SAED), and Raman spectroscopy. A comprehensive analysis is conducted to elucidate the relationships between factors such as ionic polarizability, packing fraction, bond valence, complex chemical bonding, and far-infrared reflectivity spectra with microwave dielectric properties. The results demonstrate that these ceramics exhibit a broad range of permittivity (14.30-23.18), high-quality factors (14,828-22,300 GHz), opposite temperature coefficient of resonance frequency (-16.0 to + 22.4 ppm/°C), and nice thermal conductivity (1.81-2.76 W·m-1·K-1), particularly at x = 0.30 with a near-zero τf value of +1.6 ppm/°C. The findings not only provide insights into designing MWDCs with a near-zero τf but also offer a promising route for developing advanced microwave materials with improved performance and reliability.

Exploring the photocatalytic efficacy of core–shell CeO2/TiO2 nanocomposite synthesized via solution combustion synthesis

Abstract This study investigates the photocatalytic efficacy of core–shell CeO2/TiO2 nanocomposite (CT-NC) synthesized via solution combustion synthesis. Various characterization techniques including X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), UV–visible spectroscopy (UV), photoluminescence spectroscopy (PL), Raman spectroscopy, field emission scanning electron microscopy (FESEM) along with energy-dispersive spectroscopy (EDS) analysis and high-resolution transmission electron microscopy with selected area electron diffraction (HRTEM-SAED) were employed to analyze the nanomaterials. XRD pattern confirmed the realization of cubic and tetragonal phases of CeO2 and TiO2. The vibrational modes observed below 800 cm−1 confirmed the metal-oxygen bonds of the synthesized samples. The energy bandgap (Eg) of CT-NC, as estimated from UV–vis spectra, reduced to 2.28 eV, resulting in a significant enhancement of the photocatalytic activity. The various emission peaks in the visible region due to the oxygen vacancies facilitated the generation of Reactive Oxygen Species (ROS). EDS analysis confirmed the presence of elements and the purity of the samples. Furthermore, CT-NC demonstrated remarkable dye degradation efficiency, achieving a maximum efficiency of 98.15 % under visible light irradiation for 120 min. This enhanced activity is attributed to the Advanced Oxidation Process (AOPs). Overall, the results highlight the potential of CT-NC as an efficient photocatalyst for environmental remediation.

Investigating the optical, structural, and therapeutic properties of CuO nanoparticles coated with [BMIM][BF4] Ionic liquid

This work reports a chemical synthesis of 1-butyl-3-methyl imidazolium tetrafluoroborate ionic liquid ([BMIM][BF4] IL) coated copper oxide nanoparticles (CuO-[BMIM][BF4] NPs) by using co-precipitation method. Additionally, bare copper oxide nanoparticles (CuO NPs) are prepared without the addition of the ionic liquid for comparison. Structural morphology and optical properties were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) with selected area electron diffraction (SAED), Fourier transform infrared spectroscopy (FT-IR), ultraviolet–visible spectroscopy (UV–Vis), and photoluminescence spectroscopy (PL). XRD analysis revealed the monoclinic phase of synthesised CuO NPs (with and without addition of IL) with an average crystallite size of 15.3 nm and 8.42 nm for CuO NPs and CuO-[BMIM][BF4] NPs respectively. An examination of the UV–Vis spectra revealed that the optical bandgap decreases with the addition of IL to CuO NPs. Scanning Electron Microscope (SEM) revealed the flake like morphologies in the range of nanoscale. TEM Microscope showed the conventional needle structure of CuO-[BMIM][BF4] NPs. Synthesised NPs showed antimicrobial effects against Streptococcus aureus and Pseudomonas aeruginosa as well as pathogenic fungi, including Aspergillus flavus and Candida albicans, as investigated using the disc diffusion technique. Pseudomonas aeruginosa (bacterial pathogen), Candida albicans (fungal pathogen) were significantly inhibited than the other two organisms. Additionally, the prepared CuO nanoparticles were evaluated for their anticancer properties on MCF7 human breast cancer cell lines using the MTT assay. The results indicated that the synthesised CuO nanoparticles exhibited effective cytotoxicity against MCF7 cells, with an IC50 value of 33.37 μg/mL. These findings are briefly discussed in this manuscript.

Recycling of reduced graphene oxide from graphite rods in disposable zinc battery applicable to optical sensing

We report a low cost, simple method to fabricate reduced graphene oxide (rGO) optical sensors from recycled batteries. The rGO nanosheets were exfoliated by electrochemical method under the assistant of electric arc using 5 % KOH or NaOH electrolytes. The rGO nanosheets show interlayer distances ranging from 3.98 to 6.22 Å, and thicknesses from 0.62 to 6.00 nm, corresponding from 1 to 10 layers, respectively, determined from X-ray diffraction (XRD), atomic force microscopy (AFM), and transmission electron microscopy (TEM) measurements. Selected area electron diffraction (SAED) measurement indicates that rGO nanosheets content Miller-Bravais indices of (1–210) and (0–110) planes, and the hexagonal diffraction pattern of (0–110) plane of graphene sheets with d-spacing of 2.13 Å. Low defect densities in exfoliated rGO nanosheets were confirmed by ID/IG ratios ∼0.16 to 0.18 via Raman. The rGO nanosheets exfoliated in NaOH electrolyte have 19.35 % lower oxygen content compared to those exfoliated in KOH electrolyte inspected from XPS spectra. The performance of the rGO optical sensors is controlled by defects created from oxygen functional groups formed during exfoliation process. The responsivity and response (rise) time of NaOH-exfoliated rGO sensor are 0.46 A/W and 2.3 s, respectively. These values are 21 % (for responsivity) larger and 35 % (for rise time) smaller than those of KOH-exfoliated rGO sensor. The best-in-class of high gain were demonstrated in this study for the rGO optical sensors prepared from disposed graphite rods. The results demonstrate how disposed batteries can be recycled to produce photodetectors and other optoelectronic devices using cheap and relatively nontoxic methods.

Biodegradable Acid-Based Fe2MnO4 Nanoparticles for Water Remediation.

This study demonstrated the synthesis of Fe2MnO4 modified by citric acid, a biodegradable acid, using a simple co-precipitation method. Characterization was performed using qualitative analysis techniques such as Fourier-transformed infrared spectroscopy, scanning electron microscopy equipped with energy-dispersive X-ray spectroscopy, X-ray diffraction, selected-area electron diffraction, N2 adsorption-desorption, and zero-point charge. The prepared nanoparticles had a rough and porous surface, and contained oxygenous (-OH, -COOH, etc.) functional groups. The specific surface area and average pore size distribution were 83 m2/g and 5.17 nm, respectively. Net zero charge on the surface of the prepared nanoparticles was observed at pH 7.5. The prepared nanoparticles were used as an adsorbent to remove methylene blue dye from water under various conditions. Using small amounts of the adsorbent (2.0 g/L), even a high concentration of MB dye (60 mg/L) could be reduced by about ~58%. Exothermic, spontaneous, feasible, and monolayer adsorption was identified based on thermodynamics and isotherm analysis. Reusability testing verified the stability of the adsorbent and found that the reused adsorbent performed well for up to three thermal cycles. Comparative analysis revealed that the modified adsorbent outperformed previously reported adsorbents and unmodified Fe2MnO4 in terms of its partition coefficient and equilibrium adsorption capacity under different experimental conditions.

Magneto-Luminescent Two-Dimensional Nanosheets of Gadolinium and Gold Nanocluster Assemblies with Surface Molecular Functionalization for White Light Emission.

We report the formation of photoluminescent two-dimensional (2D) crystalline nanosheet assemblies of gadolinium ions and ligand-stabilized gold nanoclusters (Gd-Au NCs). Transmission electron microscopy, selected area electron diffraction in conjunction with atomic force microscopy, and field-emission scanning electron microscopy analyses substantiated the 2D nature of Gd-Au NC nanosheets. The optical and magnetic properties of the nanosheets were investigated by photoluminescence measurements and vibrating-sample magnetometry analyses. The so-formed crystalline product was further utilized to generate a synchronous tricolor (orange, green, and blue) emission from a single excitation wavelength through an inorganic surface complexation reaction. The independent emissions were tunable after ligand functionalization by acetylsalicylic acid and fluorescein on the Gd-Au NC assembly. Interestingly, the assembled superstructure with augmented quantum yield led to white light emission at λexc ≈ 325 nm with CIE of (0.34, 0.33) and CRI value of >85 in the liquid phase. Furthermore, the ability to modulate the luminescence properties through the surface complexation of the 2D nanosheets of Au NCs may bring about new avenues toward applications in light-emitting devices, sensing, and biomedical imaging.

Hexagonal moiré superlattices, twist-angle disorder and rhombohedral-stacking in a commercially available grafoil-film

We report an advanced investigation on the structural properties of graphitic interfaces within a commercially available film of grafoil, by employing a combination of high-resolution transmission electron microscopy (HRTEM), selective area electron diffraction (SAED) and Raman mapping and point spectroscopy. We identify large-area hexagonal moiré superlattices with dimensions in the order of 2 μm ∗ 2 μm, with a periodicity ranging from D ∼ 12 nm to D ∼ 22 nm, which correspond to a variable twist angle parameter θtwist from 0.65° to 1.15°. These sample regions identified with HRTEM evidence the presence of local structural disorder (twist-angle moiré disorder). By employing SAED we identify the possible presence of a disordered A|ABAB|BCBC|CACA|A stacking sequence, which corresponds to a disordered rhombohedral phase, previously identified in nitrates-intercalated graphitic systems. The structural components and parameters associated to this phase were analysed by employing a combination of techniques, including HRTEM, SAED, Raman point and mapping spectroscopy, X-ray diffraction (XRD) and Rietveld refinements. In particular, XRD, Rietveld refinements and calculated diffractograms evidence the presence of coexisting disordered and crystalline rhombohedral phases in the analysed film.

Fabrication and characterization of Sb2O3–MoS2 nanocomposites for high performance supercapacitor applications

Binary nanocomposite-based electrodes have been studied extensively in recent times owing to their multiple oxidation states, excellent physico-chemical features, and combined morphology, which are suitable for increasing the electrochemical performance of supercapacitors. The present work deals with Sb2O3–MoS2 nanocomposites electrode for supercapacitor applications. The x-ray diffraction (XRD), Raman, scanning electron microscope (SEM), energy dispersive x-ray (EDX), high-resolution transmission electron microscopy (HRTEM), selected area electron diffraction (SAED) and x-ray photoelectron spectroscopy (XPS) characterizations have been studied to analyze the phase formation, vibrational modes, morphology, elemental composition and binding energies of the prepared Sb2O3–MoS2 nanocomposites electrode material, as well as their electrochemical measurements such as cyclic voltammetry (CV), galvanostatic charge-discharge (GCD), and electrochemical impedance spectroscopy (EIS) have been analyzed. The developed Sb2O3–MoS2 nanocomposites electrode provides a high specific capacitance of 454.3 F g−1 at the current density of 1 A g−1. Further, the hybrid supercapacitor device has been constructed which shows 104.04 F g−1 of specific capacitance at 2 A g−1 and manifests a good energy density of 24.42 Wh kg−1 at a power density of 1299.89 W kg−1. Additionally, the hybrid device Sb2O3–MoS2//AC exhibits a good capacitive retention of 90.6% and a coulombic efficiency of 100.45% at 10 A g-1 over 8000 cycles.

Particle size effect on graphene nanoribbons with iron oxide nanoparticles

The particle size effect on nanocomposites made of reduced graphene nanoribbons (GNRs) and iron oxide nanoparticles (IONPs) is studied. Three nanocomposites with different particle size were prepared by chemical reduction of IONPs formed by the co-precipitation method on graphene oxide nanoribbons. Several experimental techniques such as transmission electron microscopy, selected area electron diffraction and X-ray diffraction determined the particle size distribution and crystalline phases present in the samples. The specific surface area (SSA) of the nanocomposites was measured and discussed with the mean size of the IONPs. Depending on the mean size and surface distribution of the IONPs, samples with high SSA can be achieved. Magnetic measurements indicated that the particle size affects the magnetic properties of the nanocomposites. These results were discussed considering the effect of particle size, defects, amount of particles and interaction between the IONPs and GNRs surface. The potential application of the samples as supercapacitors was evaluated by calculating their specific capacitance from cyclic voltammetry measurements. The results showed that the specific capacitance increases with the SSA. This work confirms that the size of the IONPs significantly affects the properties of the nanocomposites, specifically the SSA, which is of great interest for various applications.

Chromoionophoric molecular probe infused bimodal porous polymer rostrum as solid-state ocular sensor for the selective and expeditious optical sensing of ultra-trace toxic mercury ions

This study presents a distinctive solid-state naked-eye colorimetric sensing approach by encapsulating a chromoionophoric probe onto a hybrid macro-/meso-pore polymer scaffold for fast and selective sensing of ultra-trace Hg(II). The customized structural/surface properties of the poly(VPy-co-TM) monolith are attained by specific proportions of 2-vinylpyridine (VPy), trimethylolpropane trimethacrylate (TM), and pore-tuning solvents. The interconnected porous network of poly(VPy-co-TM), inherent superior surface area and porosity, is captivating for the homogeneous/voluminous incorporation of probe molecules, i.e., 7-((4-methoxyphenyl)diazenyl)quinoline-8-ol (MPDQ), for the target-specific colorimetric detection. The structural morphology, surface topography, and phase characteristics of the bare poly(VPy-co-TM) monolith and MPDQ@poly(VPy-co-TM) sensor are examined using HR-TEM-SAED (High-Resolution Transmission Electron Microscopy - Selected Area Electron Diffraction), FE-SEM-EDAX (Field Emission Scanning Electron Microscopy - Energy Dispersive X-ray Spectroscopy), XPS (X-ray Photoelectron Spectroscopy), p-XRD (Powder X-Ray Diffraction), FT-IR (Fourier Transform Infrared Spectroscopy), UV-Vis-DRS (Ultraviolet-Visible Diffuse Reflectance Spectroscopy), and BET/BJH (Brunauer-Emmett-Teller / Barrett-Joyner-Halenda) analysis. The distinctive properties of the sensor reveal a constrained geometrical orientation of the MPDQ probe onto the long-range continuous monolithic network of meso-/-macropore template, enabling selective interaction with Hg(II) with peculiar color transfiguration from pale yellow to deep brown. The sensor demonstrates a linear spectral-color alliance in the 0–200 ppb concentration range for Hg(II), with quantification and detection limits of 0.63 and 0.19 ppb. The sensor efficacy is verified using certified contaminated water and tobacco samples, with excellent reusability, reliability, and reproducibility of ≥ 99.23 % (RSD ≤1.89 %) and ≥ 99.19 % (RSD ≤1.94 %) of Hg(II), respectively.

Doping Induced Enhancement of Activity and Stability for Oxygen Evolution Reaction with Isomaterially Heterostructured MnO2

A “Non-Native” phase (NNP) differs from the thermodynamically most stable bulk Native in its discrete translational symmetry. The relative difference in surface and bulk energy with respect to the native phase (NP)determines the stability of NNP. The isomaterial hetero-structured NP-NNP composite provides a pathway to assemble structures that have optimal properties of NNP and NP. The surface and sub-surface energies can also be modulated by doping as the dopants may segregate and stabilize grain boundaries. This study demonstrates that the isomaterial heterostructure of the NP, β-N MnO2, and Ramsdellite, r-NN1 MnO2, known as γ-N-NN1-MnO2 intergrowth, enhances the OER activity and stability.The hydrothermal route was used to synthesize isomaterial heterostructured γ/N-NN1-MnO2 with varying concentrations of dopants (10%, 15%, and 20% Ni and Co). X-ray diffraction was used to characterize the material, and after Rietveld refinement, phase quantification revealed that as the dopant concentration increased, the amount of the thermodynamically stable β-N MnO2 phase increased. Planes identified in XRD were also confirmed using high-resolution transmission electron microscopy (HRTEM) and the analysis of selective area electron diffraction (SAED) patterns. It appears that doping was successful based on the shifting of peaks in XRD and differences in unit cell volume and crystallite size calculated using the Debye-Scherrer equation before and after doping. With an increase in dopant concentration and thus improved OER activity, the average oxidation state as determined by X-ray photoelectron spectroscopy followed a downward trend, which is known to improve OER activity. The peaks shifted to lower frequency values as seen by Raman spectroscopy, which implies a weakening of Mn—O bond strength, indicating that dopants Ni and Co may have replaced part of the Mn atoms in the MnO2 intergrowth structure. Scanning electron microscopy (SEM) revealed spherical-shaped nanoparticles with spike-like overgrowths, which were further confirmed by HRTEM. The uniform dispersion of dopants was demonstrated by SEM and energy dispersive spectroscopy (EDS). Elemental quantification of the samples was done using EDS and scanning transmission electron microscopy (STEM). Using HRTEM, the presence of grain boundaries was confirmed.The study of dopants segregating to the grain boundary is conducted through DFT simulations. In many instances, the dopants actively contribute to the OER activity, except for the case of Ni in the NN1 sub-phase of the γ-N-NN1-MnO2 intergrowth, which is apparent by the slightly lower activity of Ni-doped samples compared to Co. This is because Ni remains in the bulk while Co segregates to the surface. A three-electrode setup (Ag/AgCl as the reference electrode, Pt mesh as the counter electrode, and catalyst as the working electrode) was used in 1M KOH to conduct electrochemical experiments. To achieve 10 mA/cm2, the 15% Co-doped electrocatalyst used the least amount of overpotential, 320 mV. According to electrochemical measurements and analysis, the doped samples show low Tafel slope, high specific activity, roughness factor, and charge transfer resistance from electrochemical impedance spectroscopy, all of which suggest improved overall activity for the oxygen evolution process (OER) for the doped over undoped samples. DFT simulations rationalize the enhancement of OER using the Bader charge analysis, the associated Gibbs free energy of the Sabatier principle plotted as the volcano plot.

Two Dimensional Structured Electrode of Nickel Oxide for Enhanced Capacitive Behaviour

Two-dimensional (2D) nickel oxide (NiO) was synthesized using carbon as templates in a single step hydrothermal route. X-ray diffraction studies revealed the formation of a single phase NiO. Crystallite size and strain in the as synthesized material were calculated using the Williamson-Hall method and Size-Strain plot. UV-Vis spectroscopy investigations provided insight into the absorption region and optical band gap of NiO, including refractive index analysis. The optical absorption indicated that the material absorbs in both UV and part of visible region, with a reduced band gap of 1.9 eV. Microstructural analysis of NiO was carried out by using high resolution transmission electron microscope (HRTEM) which confirmed the presence of nanosheets. The selected area electron diffraction pattern (SAEDP) of the corresponding area revealed the polycrystalline nature of the as synthesized NiO, with fine crystallites oriented along (111) and (220) planes. Morphological analysis was performed using field emission scanning electron microscopy (FESEM), revealing the presence of 2D nano-sheets. Elemental compositional analysis was carried by using energy-dispersive X-ray spectroscopy (EDS) as an attachment of FESEM and TEM, which showed the presence of nickel and oxygen only. Nyquist plot and cyclic voltammetry depicts the capacitive behaviour, suggesting the material’s suitability for capacitor/supercapacitor applications.

Study the influence of Ag+ nanoparticles on the surface of the Sr1-xAgxFeO3-δ perovskite on optical, magnetic and antibacterial properties

Recently, we produced low cost SrFeO3-δ perovskite with antibacterial properties. In this study to improve the antibacterial properties of SrFeO3-δ perovskite, we doped it with silver. Ag+ nanoparticles on the surface of the Sr1-xAgxFeO3-δ perovskite samples were prepared by sol-gel method. Structural properties of these samples were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), selected area electron diffraction (SAED), high-resolution TEM (HR-TEM), EDS elemental mapping and Fourier transform infrared spectrometer (FT-IR). These techniques confirmed the presence of small amount of cubic Ag spherical nanoparticles on the surface of the cubic Sr1-xAgxFeO3-δ perovskite structure. Further, X-ray photoelectron spectroscopy (XPS) for these samples revealed the presence of Ag1+ ions, oxygen vacancies and mixed valence states of Fe ions on the surface of the samples. The energy band gap of these samples was estimated using Kubelka–Munk equation and its value increased with increasing Ag up to x = 0.10. Additionally, Magnetic hysteresis (M − H) loops revealed that these samples displayed antiferromagnetic behavior with a small amount of ferromagnetic order. Finally, the antibacterial properties of these samples revealed that the antimicrobial activities were improved with increasing Ag (x = 0.10). Our results showed that Ag+ nanoparticles on the surface of the Sr1-xAgxFeO3-δ perovskite samples are a promising antimicrobial agent.Graphical

Aluminum doped non-stoichiometric titanium dioxide as a negative electrode material for lithium-ion battery: In-operando XRD analysis

Lithium-ion batteries (LIB) with titanium dioxide as anode material emerged as one of the most energy-storage systems. In this study, we investigate aluminum-doped non-stoichiometric titanium dioxide synthesized using sol-gel method and subsequent reduction treatment. Different analysis techniques, such as X-ray diffraction (XRD), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), Cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) tests are conducted for the analysis of material and performance of the battery. The XRD results affirmed that the sample consisted of pure titanium-dioxide phases with no other precipitated phases, such as aluminum oxide (α-Al2O3 or γ-Al2O3). XPS analysis evident that aluminum was successfully incorporated into the titanium-dioxide lattice and the presence of Ti3+ and oxygen vacancy signals confirmed its non-stoichiometric nature. TEM images implies that doping and its extent did not significantly affect the size and morphology of the nanoscale particles. The selected area electron diffraction shows that the sample consisted of a mixture of the anatase and rutile phases. The best-performing electrode was found to be the one composed of 1 % aluminum-doped non-stoichiometric titanium dioxide. After 200 charge-discharge cycles, the battery maintained a capacity of 195 mAh/g, retaining 97.5 % of its reversible capacity. Cyclic stability test under high current condition shows that the capacity remained at 157 mAh/g without any noticeable decay after 750 charge-discharge cycles at a 1 C rate. This material exhibited the lowest impedance and the highest lithium-ion diffusion rate. Additionally, in situ synchrotron-based XRD indicates coexistence of three phases such as a new reversible intermediate phase LiTiO2, a partially irreversible intermediate phase Li0.55TiO2, and the anatase phase. The analysis results indicated that the peak intensities and angular shifts were associated with the phase changes that occurred during charge and discharge of the electrochemical processes. The interaction mechanism study between lithium ions and the lattice of mixed phase (anatase, rutile) identified the occurrence of non-uniform stress resulting from lithium-ion insertion in the rutile phase, in addition to the irreversible reactions in both the rutile and anatase phases. Through the synergistic effect of heteroatom doping and oxygen vacancy treatment, the conductivity of titanium dioxide is enhanced, leading to improved performance in capacity, impedance, cycle life, and rate as an anode material in LIBs.

A high-speed method to obtain Ni-Zn ferrite nanoparticles by microwave hydrotalcite decomposition for magnetic applications

Nanoparticles of Zn0.375Ni0.625Fe2O4 ferrite were successfully synthesized using an innovative, rapid, and efficient synthesis method based on microwave-assisted hydrotalcite decomposition, enabling nanoparticle crystallization in less than 15 minutes. A single composition was studied to better assess the impact of the synthesis method on structural, morphological, and magnetic properties. This new synthesis route was compared with the traditional ceramic method. The prepared hydrotalcite was analyzed by high-resolution transmission electron microscopy (HRTEM), identifying hydrotalcite diffraction planes consistent with selected area electron diffraction (SAED) and X-ray diffraction (XRD) patterns. The decomposition phases of the hydrotalcite were identified by simultaneous thermogravimetric and differential thermal analysis (DTA/TG). After hydrotalcite decomposition, the ferrite obtained was analyzed by XRD, confirming a single-phase cubic structure. Scanning electron microscopy (SEM) micrographs revealed nanoparticles less than 100 nm in size with the new method and larger than 2 µm with the traditional route. At a temperature of 5 K, the M-H graph obtained with a superconducting quantum interference device (SQUID) indicated that the spinel-type ferrite exhibited a smooth ferrimagnetic behavior, which was also corroborated by electron paramagnetic resonance (EPR). Magnetic saturation values of 105.73 emu/g were obtained in the synthesis microwave-assisted hydrotalcite decomposition and 51.49 emu/g in the traditional synthesis, representing an increase of over 100 %. The two synthesis methods were also compared using density functional theory (DFT) calculations, confirming the influence of morphology on magnetic properties, obtained thanks to different synthesis methods. These results indicate that the synthesized Ni-Zn spinel ferrite nanoparticles can be used in high-frequency applications, such as ceramic induction plates.

Reaction-controlled shape evolution and insights into the growth mechanism of CsPbBr3 nanocrystals

The correlation between structural transformation and optical characteristics of cesium lead bromide (CsPbBr3) nanocrystals (NCs) suggests insights into their growth mechanism and optical performance. Systematic control of reaction parameters led to the successful fabrication of on-demand shape-morphing CsPbBr3 NCs. Transmission electron microscopy observations showed that the shape transformation from nanocubes to microcrystals could be accelerated by increasing the precursor:ligand molar ratio and reaction time. Further evidence for orthorhombic CsPbBr3 NCs was obtained from their selected-area electron diffraction pattern, which exhibits a twin domain induced by the presence of large NCs. Likewise, we observed a substantial decrease in photoluminescence (PL) intensity of CsPbBr3 due to surface decomposition or surface ligand loss resulting from increased size. In addition, fusion of smaller particles having other dimensionality induced the increase in the PL full-width at half maximum. In particular, existence of larger bulk material caused a reduction in the peak intensity in the absorption spectra and a trend of decreasing tendency in intensity of the absorption bands related to bromoplumbate species provided direct evidence of fully converted Cs-oleate.

Optimization of three-dimensional electron diffuse scattering data acquisition

The diffraction patterns of crystalline materials with local order contain sharp Bragg reflections as well as highly structured diffuse scattering. In this study, we quantitatively show how the diffuse scattering in three-dimensional electron diffraction (3D ED) data is influenced by various parameters, including the data acquisition mode, the detector type and the use of an energy filter. We found that diffuse scattering data used for quantitative analysis are preferably acquired in selected area electron diffraction (SAED) mode using a CCD and an energy filter. In this study, we also show that the diffuse scattering in 3D ED data can be obtained with a quality comparable to that from single-crystal X-ray diffraction. As electron diffraction requires much smaller crystal sizes than X-ray diffraction, this opens up the possibility to investigate the local structure of many technologically relevant materials for which no crystals large enough for single-crystal X-ray diffraction are available.

Microstructure, mechanical properties and cutting performance of CVD Ti(B,N) coatings

TiB0.19N1.06, TiB0.70N0.66, and TiB1.23N0.19 coatings were deposited on cemented carbide via the chemical vapor deposition (CVD) method based on the calculated phase diagrams of the Ti–B–N system. The microstructures, mechanical properties and cutting performances of the Ti(B,N) coatings were systematically studied via X-ray diffraction (XRD), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), nanoindentation, etc. The coating compositions obtained via thermodynamic calculations show the same trend as the experimental values. The XRD and selected area electron diffraction (SAED) results of the coatings reveal that the phase assemblages transform from a dominant cubic structure of TiB0.19N1.06 to a hybrid of cubic and hexagonal structure of TiB0.70N0.66 and finally to a dominant hexagonal structure of TiB1.23N0.19. According to the XPS results, the TiB0.19N1.06 and TiB0.70N0.66 coatings consist of the crystalline phases TiN and TiB2 as well as amorphous BN and TiB, and the TiB1.23N0.19 coating mainly consists of the crystalline phases TiB2 and TiN. The hardness values of the TiB0.19N1.06, TiB0.70N0.66, and TiB1.23N0.19 coatings are 33.6, 35.1, and 39.1 GPa, respectively. The content of amorphous phase in the Ti(B,N) coatings decreases while the hardness increases as the B content increases and N content decreases. The TiB0.19N1.06 coating exhibits a composite structure of nanocrystallite embedded in amorphous matrix. The TiB1.23N0.19 coated tool prepared in this study demonstrates excellent performance in milling titanium alloy TC18 with a long cutting life up to 56.1 min, an increase of ∼9 % and ∼28 % compared to the TiB1.98 coated tool and commercial grade deposited with CVD TiB2 coating, respectively.

CuO nanoparticles for enhanced photoelectrochemical HER activity

Cupric oxide nanoparticles are a p-type semiconductor that can be used as a hole transport layer material in perovskite solar cells owing to their high electrical conductivity and stability. In the present work, CuO nanoparticles are synthesized using the hydrothermal technique, and their photoelectrochemical properties are studied through cyclic voltammetry. The X-ray diffraction patterns of the nanoparticles were analyzed for phase formation, revealing the monoclinic phase and further verified by the Rietveld Refinement. Thermogravimetric analysis shows a total weight loss of 13.47%. Transmission electron microscopy analysis suggests the formation of nanoparticles with an average size of 34 nm. The selected area electron diffraction analysis reveals the crystalline structure of the nanoparticles. The absorbance spectra of the nanoparticles were analyzed by UV–visible measurement, and Tauc's relation was used to estimate the optical bandgap. The XPS results align with the XRD results, indicating the formation of pure CuO nanoparticles. The developed catalyst's photoelectrochemical performance was investigated in the neutral solution for the hydrogen evolution reaction activity, and a high photocurrent density of −41.57 mA/cm2 was observed versus −0.6 V vs. RHE.