Efficient and Ultrafast Oxyorthosilicate Scintillator by Activator Valence State Manipulation.

There is an urgent need for faster, brighter, and more controllable scintillation materials in advanced nuclear medicine, high-energy physical experiments, and dark matter particle detection. Nevertheless, the trade-off between high emission efficiency and fast timing characteristics remains a common challenge in the entire optical field. To address this issue, we develop a composition engineering strategy that involves multisite selective doping. This strategy aims to transform nearly all Ce3+ into fast-emitting Ce4+ while synergistically suppressing the electron traps. Even at very low doping concentrations, the designed Ca2+, Al3+, and Ce3+ tridoped oxyorthosilicate exhibits a scintillation decay (τd) acceleration of 20%, accompanied by a 25% increase in light yield (LY). The ratio of emission efficiency and timing characteristics (LY/τd) can be enhanced by 56%, which realizes the perfect balance of high LY and fast τd. Our work provides a method for designing efficient, ultrafast, and controllable scintillators in multicomponent systems, thus paving the way for high-resolution radiation detection and imaging applications.

Tuning Coordination in ZIF-67 Through the Solid-State Thermal Synthesis for Balancing Structural Stability and Catalytic Reactivity.

Tailor-made unsaturated coordination of metal ions or organic linkers in zeolitic imidazole frameworks (ZIFs) has great potential in tuning the ZIFs' properties and reactivity for their applications. Taking advantage of the solid-state thermal (SST) method as a facile and eco-friendly synthesis method, the rational coordination of metal ions with imidazole ligands in ZIF-67 through the SST method is investigated. The rational precursor ratio (metal-to-ligand source) under the solvent-free SST method emerges as a perfect strategy to tune the coordinately unsaturated sites within the ZIF-67 frameworks. Different analysis techniques, computational methods (DFT), and catalytic model reactions examine unsaturated coordination in ZIF-67 materials (defect structures). The unsaturated coordination provides unique characteristic properties on materials with excellent catalytic performance. However, the higher reactive properties are negotiated with weaker structural stability on materials. In addition, the post-SST approach is applied to enable rational coordination and modify the pristine ZIF-67 materials. The post-SST method rearranges and modifies coordination in the framework of materials. These findings are crucial to understanding the role of the uncoordinated degree to balance with structural stability based on ZIF-67, which is critical for effective heterogeneous catalysts.

Defect by design: Harnessing the "petal effect" for advanced hydrophobic surface applications.

HYPOTHESIS: In the interfacial wetting boundary, the superhydrophobic surface is often damaged, and the anisotropic wettability of its surface has attracted many researchers' attention. The "petal effect" surface has typical anisotropic wettability. We predict that under the dual conditions of structural defects and high impact velocity, the "petal effect" becomes more adhesive on the surface. EXPERIMENTS: This study refers to the droplet state on rose petals, structural defects were constructed on the superhydrophobic surface. This paper studies the influence of macro-structural defects on the wettability change from natural to bionic "lotus effect" to "petal effect" in both static and dynamic angles. FINDINGS: Macro defects significantly change the static contact angle of the superhydrophobic surface. The higher the impact velocity of the droplet, the higher the energy dissipation of the "petal effect" surface (DSHS), which improves the adhesion of the surface to the droplet and prolongs the contact time. It is found that the defect structure and high impact velocity will directly affect the deposition and desorption of droplets on the superhydrophobic surface, and they are both essential. This wetting dynamic law is very likely to be helpful in the quantitative design of defect structure scale for dynamic desorption of droplets on superhydrophobic surfaces.

Temperature Dependence of the Number of Defect-Structures in Poly(vinylidene fluoride).

Poly(vinylidene fluoride) (PVDF) is predominantly characterized by alternating CH2 and CF2 units in a polymer backbone, originating from the head-to-tail addition of monomers or regular propagation. Due, to a small extent, to inverse monomer addition, so-called defect structures occur which influence the macroscopic properties of PVDF significantly. The amount of defect structures in the material is determined by the polymerization conditions. Here, the temperature dependence of the fraction of defect structures in PVDF obtained from polymerizations between 45 and 90 °C is reported. We utilized 19F-NMR spectroscopy to determine the fraction of defect structures as a function of temperature. To derive kinetic data, the polymerization of VDF is considered a quasi-copolymerization described by the Terminal Model involving four different propagation reactions. Based on the experimentally determined temperature-dependent fractions of defect structures, the known overall propagation rate coefficient, and taking into account the self-healing behavior of the macroradical, the Arrhenius parameters of the individual propagation rate coefficients were determined using the Monte Carlo methods.

High-entropy engineering with regulated defect structure and electron interaction tuning active sites for trifunctional electrocatalysis.

High-entropy alloy nanoparticles (HEANs) possessing regulated defect structure and electron interaction exhibit a guideline for constructing multifunctional catalysts. However, the microstructure-activity relationship between active sites of HEANs for multifunctional electrocatalysts is rarely reported. In this work, HEANs distributed on multi-walled carbon nanotubes (HEAN/CNT) are prepared by Joule heating as an example to explain the mechanism of trifunctional electrocatalysis for oxygen reduction, oxygen evolution, and hydrogen evolution reaction. HEAN/CNT excels with unmatched stability, maintaining a 0.8V voltage window for 220 h in zinc-air batteries. Even after 20 h of water electrolysis, its performance remains undiminished, highlighting exceptional endurance and reliability. Moreover, the intrinsic characteristics of the defect structure and electron interaction for HEAN/CNT are investigated in detail. The electrocatalytic mechanism of trifunctional electrocatalysis of HEAN/CNT under different conditions is identified by in situ monitoring and theoretical calculation. Meanwhile, the electron interaction and adaptive regulation of active sites in the trifunctional electrocatalysis of HEANs were further verified by density functional theory. These findings could provide unique ideas for designing inexpensive multifunctional high-entropy electrocatalysts.

Transition-state defect structure: A new strategy for TiO2-based porous materials to enhance photodegradation of pollutants.

The aim of this paper is to investigate the derived structure and properties of Zeolitic Imidazolate Framework-8 (ZIF-8), and the effect of residual structural on the catalytic properties after loading with Titanium Dioxide (TiO2). For this purpose, we ingeniously prepare C-ZIF-8@TiO2 with a transition-state defect structure and apply it for efficiently degrading organic dye wastewater represented by Rhodamine B (Rh-B). Thanks to the transition-state defect structure loaded with TiO2 and ZIF-8 self-derived Carbon (C) and Zinc Oxide (ZnO), the catalytic performance of C-ZIF-8@TiO2 is superior to that of TiO2 and normal TiO2/ZIF-8 composites, and it is effective in degrading a variety of antibiotics and dyes. The related characterization also shows good photovoltaic properties and long-term durability for C-ZIF-8@TiO2. The mechanism on free radical action is elucidated and the possible degradation pathway for Rh-B is speculated. Therefore, C-ZIF-8@TiO2 provides a new strategy for the degradation of organic pollutants in water bodies.

Mechanism of biochar composite (BN3Z0.5BC) activated peracetic acid for efficient antibiotic degradation: Synergistic effect between free radicals and non-free radicals.

This study utilized corn straw as the feedstock to synthesize biochar (BC) loaded with cobalt-zeolitic imidazolate framework nanoparticles and boron nitride quantum dots. The prepared BC composite, named BN3Z0.5BC, efficiently activated peracetic acid (PAA), resulting in the degradation of 94.8% of sulfadiazine (SDZ) in five minutes. Compared to pure BC, the SDZ removal rate increased nearly 5-fold. Mechanism analysis revealed that the main degradation pathway involves synergism between free and non-free radicals. The defect structure on the BC surface possesses a high charge density, stimulating PAA to produce more active species, while nitrogen-oxygen vacancy formation significantly promotes charge transfer. Besides, the unique structure of BC ensures good stability and recyclability, effectively controlling metal leaching. The BN3Z0.5BC/PAA system shows promising applicability across various water matrices, indicating a favorable application outlook.

Structure, Optical Properties and Physicochemical Features of LiNbO3:Mg,B Crystals Grown in a Single Technological Cycle: An Optical Material for Converting Laser Radiation.

Two series of LiNbO3:Mg:B crystals have been grown and studied. Two doping methods-have been used. The crystals-have been co-doped with Mg and a non-metallic dopant, B. The physicochemical features of the growth-have been considered for LiNbO3:Mg:B crystals obtained from a boron-doped melt. The charge-has been prepared using different technologies: homogeneous (HG) and solid-phase (SP) doping. The same two methods have been used to grow single-doped LiNbO3:Mg crystals. A control near-stoichiometric (NSLN) crystal-has been grown via the HTTSSG (high-temperature top-seeded solution growth) method from a congruent melt (Li/Nb ≈ 0.946) with 5.5 wt% K2O. The characteristics of the LiNbO3:Mg:B crystals-have been compared with those of the LiNbO3:Mg and NSLN crystals. Physicochemical and structural reasons have been established for the differences in the distribution coefficients of magnesium (KD) during the growth of the HG- and SP-doped LiNbO3:B:Mg and LiNbO3:Mg crystals. The optical characteristics of the LiNbO3:B:Mg crystals-have been studied via optical spectroscopy, laser conoscopy and photoinduced light scattering (PILS). The influence of boron on the microstructure, compositional and optical uniformities and optical damage resistance of the LiNbO3:Mg:B crystals-has been estimated. Optimal technological approaches to growing optically uniform LiNbO3:B:Mg crystals have been determined. LiNbO3:Mg:B crystals have been shown to have a significant advantage over the commercially used LiNbO3:Mg crystals since large LiNbO3:Mg:B crystals can be grown without stripes. Such stripes usually appear perpendicular to the growth axis. In addition, the photorefractive effect is suppressed in LiNbO3:Mg:B crystals at lower magnesium concentrations ([Mg] ≈ 2.5 mol%) than in LiNbO3:Mg ([Mg] ≈ 5.5 mol%).

Constructing oxygen vacancy-rich MXene @Ce-MOF composites for enhanced energy storage and conversion.

Oxygen vacancies can regulate the coordination structure and electronic states of atoms, thus promoting the formation of surface-active sites and increasing the conductivity of the electrode material. This work presents a design for MXene@Ce-MOF composites with abundant oxygen vacancies. The hydroxyl groups on the surface of monolayer MXene attract cerium ions, which create surface defects in Ce-MOF and further promote the formation of oxygen vacancies. This results in a significant improvement in energy storage capacity, as well as performance in oxygen evolution reaction (OER) and hydrogen evolution reaction (HER). The MXene@Ce-MOF composite exhibits a specific capacity of 496 F g-1, which is 1.8 times higher than that of pure Ce-MOF and 3.5 times higher than MXene alone. At a current density of 10 mA cm-2, the overpotential for oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) is as low as 270 and 220 mV, respectively, and the composite exhibits excellent cycling stability. Oxygen vacancy-based MOF composites play a crucial role in electrocatalysis and energy conversion.

Hitting the mark: probing at the initiation site allows for accurate prediction of a thin shell's buckling load.

Geometric imperfections are understood to play an essential part in the buckling of a thin shell, but how multiple defects interact to control the onset of failure remains unclear. Here, we examine the failure of real cylindrical shells by experimentally poking soda cans with a large imparted dimple. By high-speed imaging of the can's surface, the initiation of buckling from axial loading is directly observed, revealing that larger dimples tend to set the initial buckling location. However, the influence of the shell's background geometric imperfections can still occasionally dominate, causing initiation to occur far from the dimple. In this situation, probing at the dimple leads to an over-prediction of the axial capacity. Using finite-element simulations, we understand our experimental results as a competition between the large dimple and the shell's inherent defect structure. In our simulations, we empirically observe a deformation-based criterion that connects the ideal poking location to the initiation site. This article is part of the theme issue 'Probing and dynamics of shock sensitive shells'.

Correlation between Infrared Absorption and Lithium Sublattice Disorder in Magnesium-Doped Lithium Niobate.

Lithium niobate is a ferro- and piezoelectric material with excellent optical properties and a wide variety of applications. The defect structures of congruent and Mg-doped crystals are still under intense discussion. In this work, undoped lithium niobate and magnesium-doped lithium niobate grown from congruent melt with the addition of 0 to 9 mol% MgO were investigated by infrared absorption, establishing the dependence of the absorbance on the Mg-doping level in two bands related to OH- stretching vibrations. The absorption band at 3485 cm-1 peaks at a MgO concentration in melt of 1 mol% and vanishes for MgO concentrations above the threshold level for optical damage suppression (4.8 mol%). A corresponding peak occurs in the minimum yield of the 7Li(p,α)4He reaction during ion channeling measurements, indicating a maximum of disorder in the Li sublattice. A possible explanation for this correlation is the attribution of this absorption band to ilmenite stacking fault sequences instead of isolated NbLi antisites in undoped and low-doped material. On the other hand, the OH- absorption band at 3535 cm-1 stays weak up to the MgO concentration threshold, and then increases, hinting to a defect related to the increase of vacancies due to the lack of charge compensation.

Oxidation state, local structure distortion, and defect structure analysis of Cu doped α-MnO2 correlated to conductivity and dielectric properties.

Cu-doped MnO2 with the composition of Mn1-xCuxO2 (x = 0-0.15) was synthesized and characterized. The synthesis was carried out by hydrothermal method at 140 °C for 5 h of reaction dwell time. The characterizations include X-Ray Diffraction (XRD), Microscopy, X-ray Absorption Spectroscopy (XAS), and Impedance complex analysis. It was revealed that all samples have nanorod morphology. Their size increases with the increasing dopant. Additionally, K ions are detected by EDX. All samples pose α-MnO2 type structures performing (2 × 2) and (1 × 1) tunnels permitting large ions incorporated and oxygen deficiency. The octahedron was distorted to elongate up to x = 0.10, then compressed for x = 0.15, inducing the Jan Teller effect. Oxidation state analysis revealed that the manganese has Mn3+ and Mn4+, while the copper is mainly attributed to Cu2+ and Cu3+ respectively. The small ionic size and highly oxidized Cu3+ substitute Mn4+, while Cu2+ substitutes Mn3+ or simultaneously with the larger K+ incorporated in the tunnel. Accordingly, the defects to exist in the sample, namely C u M n ' , M n M n ' , V O • • , and e ' . Electrical characterization at room temperature revealed that the conductivity of Cu-doped MnO2 is dominated by electrons influenced by the various oxidation state of the cations in the octahedron sites, while space charges dominate the dielectric response.

Electrochemical Activation of Oxygen Vacancy-Rich Nitrogen-Doped Manganese Carbonate Microspheres for High-Performance Aqueous Zinc-Ion Batteries.

Aqueous zinc-ion batteries (ZIBs) are considered as one of the ideal devices for large-scale energy storage because of their safety, low cost, and nontoxicity. Unfortunately, the choice of cathode materials for ZIBs is still limited. Herein, a novel oxygen vacancy-rich nitrogen-doped MnCO3 (MnCO3@N) microsphere is reported as a cathode material for rechargeable ZIBs, which displays a relatively high reversible capacity of 171.6 mAh g-1 at 100 mA g-1, outstanding rate performance, and long-term cyclic stability up to 1000 cycles at 1000 mA g-1. The better electrochemical performances of MnCO3@N should be attributed to the introduction of oxygen vacancies in the MnCO3 microcrystal by nitrogen doping, which not only improves the conductivity of MnCO3 microspheres but also creates more active sites for zinc-ion diffusion. In addition, the energy storage mechanism of the MnCO3@N microspheres is systematically investigated. During the initial charge process, the MnCO3@N microspheres are activated to form MnO@N due to the insertion of Zn2+, and partial MnO@N is further oxidized into layered-type MnO2@N, which becomes a part of the active material for subsequent energy storage. This work not only provides a new insight for the ZIB cathode but also deepens the understanding of the energy storage mechanism of carbonate materials.

Thermodynamics of Formation and Disordering of YBaCo2O6-δ Double Perovskite as a Base for Novel Dense Ceramic Membrane Materials.

Differential scanning calorimetry studies of the complex oxide YBaCo2O6-δ (YBC), combined with the literature data, allowed outlining the phase behavior of YBC depending on the oxygen content and temperature between 298 K and 773 K. The oxygen nonstoichiometry of single-phase tetragonal YBC was measured at different temperatures and oxygen partial pressures by both thermogravimetric and flow reactor methods. The defect structure of YBC was analyzed. As a result, the thermodynamic functions (∆Hi○, ∆Si○) of the defect reactions in YBC were determined. Experimental data on the oxygen content and those calculated based on the theoretical model were shown to be in good agreement. Standard enthalpies of formation at 298.15 K (∆Hf○) were obtained for YBC depending on its oxygen content using solution calorimetry. It was found that ∆Hf○ = f(6-δ) function is linear in the range of (6-δ) from 5.018 to 5.406 and that its slope is close to the value of the enthalpy of the quasichemical reaction describing oxygen exchange between the oxide and ambient atmosphere, which confirms the reliability of the suggested defect structure model.

Multilayer Conductive Hybrid Nanosheets as Versatile Hybridization Matrices for Optimizing the Defect Structure, Structural Ordering, and Energy-Functionality of Nanostructured Materials.

The hybridization of conductive nanospecies has garnered significant research interest because of its high efficacy in improving the diverse functionalities of nanostructured materials. In this study, a novel synthetic strategy is developed to optimize the defect structure, structural ordering, and energy-related functionality of nanostructured-materials by employing a multilayer multicomponent two-dimenstional (2D) graphene/metal oxide/graphene nanosheet (NS) as a versatile hybridization matrix. The hybridization of the robust trilayer, polydiallyldiammonium (PDDA)-anchored reduced-graphene oxide (prGO)/metal oxide/prGO NS effectively enhance the structural ordering and porosity of the hybridized MoS2 /MnO2 NS through suppression of defect formation and tight stacking. In comparison with monolayer rGO/RuO2 NS-based homologs, the 2D superlattice trilayer prGO/RuO2 /prGO NS hybrids deliver better functionalities as a hydrogen evolution electrocatalyst and as a supercapacitor electrode, demonstrating the merits of hybridization with multilayer NSs. The advantages of using multilayer multicomponent conductive NSs as hybridization matrices arise from the enhancement of charge and mass transport through the layer flattening or defect suppression of the hybridized NSs and the increase in porosity, as evidenced by density functional theory calculations. Finally, the universal utility of multilayer NSs is confirmed by investigating the strong effect of the stacking order on the electrocatalytic functionality of MoS2 /rGO/RuO2 films fabricated through layer-by-layer deposition.

Atomistic Observation of Temperature-Dependent Defect Evolution within Sub-stoichiometric WO3-x Catalysts.

Tunable crystalline defects endow WO3-x catalysts with extended functionalities for a broad range of photo- and electric-related applications. However, direct visualization of the defect structures and their evolution mechanism is lacking. Herein, aberration-corrected and in situ transmission electron microscopy was complemented by theoretical calculations to investigate the effect of temperature on the defect evolution behavior during hydrogenation treatment. Low processing temperature (100-300 °C) leads to the occurrence of randomly distributed oxygen vacancies within WO3-x nanosheets. At higher temperatures, oxygen vacancies become highly mobile and aggregate into stacking faults. Planar defects are prone to nucleate at the surface and develop in a zigzag form at 400 °C, while treating at 500 °C promotes the growth of {200}-type stacking faults. Our work clearly establishes that the atomic configuration of the defects in WO3-x samples could be manipulated by regulating the hydrogenation temperature. This study not only expands our understanding of the structure-function relationships of sub-stoichiometric tungsten oxides but also unlocks their full potential as advanced catalysts by tuning stoichiometry in a controlled manner.

Tensile Properties and Deformation of AISI 316L Additively Manufactured with Various Energy Densities.

Additive manufacturing (AM) is an emerging fabrication technology that offers unprecedented potential for manufacturing end-to-end complex shape customized products. However, building products with high performance by AM presents a technological challenge. Inadequate processing parameters, fabrication environment or changes in powder properties may lead to high defect density in the part and poor mechanical properties. Microstructure, defect structure, and mechanical properties of AISI 316L stainless steel pieces, additively manufactured by the laser powder bed fusion method using three different volume energy densities (VEDs), were investigated and compared with those of a commercial wrought AISI 316L sheet. Scanning and transmission electron microscopies were employed for characterization of grain and defect structures, and mechanical properties were determined by tensile testing. It was found that the number of defects such as pores and lack of fusion in AM specimens did not affect the strength, but they impaired the post-uniform elongation, more significantly when processed with the low VED. Twinning was found to be an active deformation mechanism in the medium and high VED specimens and in the commercially wrought material in the later stage of straining, but it was suppressed in the low VED specimens presumably because the presence of large voids limited the strain attained in the matrix.

Lattice Engineering to Simultaneously Control the Defect/Stacking Structures of Layered Double Hydroxide Nanosheets to Optimize Their Energy Functionalities.

An effective lattice engineering method to simultaneously control the defect structure and the porosity of layered double hydroxides (LDHs) was developed by adjusting the elastic deformation and chemical interactions of the nanosheets during the restacking process. The enlargement of the intercalant size and the lowering of the charge density were effective in increasing the content of oxygen vacancies and enhancing the porosity of the stacked nanosheets via layer thinning. The defect-rich Co-Al-LDH-NO3- nanohybrid with a small stacking number exhibited excellent performance as an oxygen evolution electrocatalyst and supercapacitor electrode with a large specific capacitance of ∼2230 F g-1 at 1 A g-1, which is the largest capacitance of carbon-free LDH-based electrodes reported to date. Combined with the results of density functional theory calculations, the observed excellent correlations between the overpotential/capacitance and the defect content/stacking number highlight the importance of defect/stacking structures in optimizing the energy functionalities. This was attributed to enhanced orbital interactions with water/hydroxide at an increased number of defect sites. The present cost-effective lattice engineering process can therefore provide an economically feasible methodology to explore high-performance electrocatalyst/electrode materials.

Higher Light Extraction Efficiency in Organic Light-Emitting Devices by Employing 2D Periodic Corrugation.

Photons trapped in the form of waveguide (WG) modes associated with the organic-organic interface and in the form of surface plasmon polariton (SPP) modes associated with the metallic electrode-organic interface result in a large energy loss in organic light-emitting devices (OLEDs). Introducing gratings onto the metallic electrode is especially crucial for recovering the power lost to the associated SPP modes. In our research, we demonstrate the efficient outcoupling of SPP modes in TE mode by two-dimensional (2D) grating, which cannot excited in one-dimensional (1D) grating OLED. This causes a 62.5% increase in efficiency from 2D grating OLED than 1D grating OLED. The efficient outcoupling of the WG and SPP modes is verified by the numerical simulation of both the emission spectra and the field distribution.

Development of Melilite-Type Oxide Ion Conductors.

Lowering the operating temperature of solid oxide fuel cells (SOFCs) requires high performance oxide ion conductor electrolytes. Recently tetrahedra-based structures have been attracting considerable attention for oxide ion conductor development, among which the layered tetrahedral network melilite structure appears particularly interesting owing to its remarkable capability to accommodate and transport interstitial oxide ions, compared with isolated tetrahedral anion structures. Stabilization and migration mechanisms of interstitial oxide ions in melilites have been systematically investigated using local structural relaxation from both electrostatic Coulomb interaction and chemical bonding aspects based on atomic and electronic structures respectively using experimental and theoretical approaches. These reveal cationic size and chemical bonding effects on stabilization and migration mechanisms of interstitial oxide ions. Lately, full crystallization from glass, an innovative synthesis method, was employed to produce new metastable melilite oxide ion conductors which are inaccessible using classic solid state reaction owing to cationic size effect. Finally, the thermal and chemical stability at low temperature and the high oxide ion conductivity of the best melilite oxide ion conductors based on LaSrGa3 O7 are likely to provide real possibilities of applications of melilite-type electrolytes in SOFCs and other related devices.