Search Results (834)

The growing demand for efficient, stable, and environmentally friendly materials for next-generation optoelectronic and photovoltaic applications has attracted significant interest in double perovskite compounds. First-principles density functional theory (DFT) calculations were performed to systematically investigate the structural, mechanical, electronic, and optical properties of Ba₂MReO₆ (M = Li, Na, K, and Rb) double perovskites. Structural optimization confirms that all compounds crystallize in the cubic Fm3̅m symmetry. The thermodynamic and geometric stability of the series is checked with negative formation energies and tolerance factor analyses (t, μ, τ). Mechanical analysis confirms that all compounds are mechanically stable; Ba₂LiReO₆ is the stiffest, while Ba₂RbReO₆ shows moderate stiffness with the highest ductility. Furthermore, ab initio molecular dynamics (AIMD) simulations at room temperature confirm the dynamical stability of all compounds, with negligible fluctuations in total energy under thermal conditions. The calculated band structures using both GGA-PBE and HSE06 hybrid functionals reveal that all compounds possess indirect band gaps, with HSE06 values of 2.236 eV for Ba₂LiReO₆, 2.133 eV for Ba₂NaReO₆, 2.116 eV for Ba₂KReO₆, and 1.395 eV for Ba₂RbReO₆. Optical measurements indicate that it is highly polarizable by dielectric polarizability, has high absorption coefficients (approximately 10⁶ cm⁻¹), and has large optical conductivity in the UV, with large inter-band interactions between 2 and 4 eV. The suitable band gap and favorable optical characteristics suggest that Ba₂RbReO₆ is the most promising candidate for photovoltaic and solar-cell applications. Full article

A novel Dy³⁺-doped self-activated Sr₂NaMg₂V₃O₁₂ (SNMVO) phosphor was synthesized via a high-temperature solid-state reaction method. Its microstructure, surface morphology, valence state, and luminescence properties were investigated. The results showed that the prepared phosphor exhibited bright green emission at 521 nm and yellow emission at 575 nm under 345 nm excitation. The luminescence intensity showed a strong concentration dependence, with an optimal Dy³⁺ ion doping concentration of 0.05 mol, and the concentration quenching (CQ) mechanism was dipole–dipole (d-d) interaction. Energy transfer between vanadate and Dy³⁺ was observed, with a maximum transfer efficiency of 63.5%. The thermal activation energy (0.1859 eV) indicated good thermal stability. Furthermore, this phosphor can be used as a yellow phosphor for white light-emitting diodes (wLEDs) and for anti-counterfeiting patterns. Full article

This study describes a comparative assessment of the structural properties, mechanical properties and gamma-ray shielding effectiveness of monzogranite to determine whether or not they can be used for sustainable shielding construction materials. The results of the petrographic, X-ray fluorescence (XRF), X-ray diffraction (XRD), and energy dispersive spectroscopy (EDS) analyses reveal that the monzogranite is composed essentially of quartz, K-feldspar, plagioclase and biotite. The SiO₂ contents of all the monzogranite studied also indicated that they are highly crystalline (70.77% to 73.34% SiO₂ by weight) and chemically stable (therefore, monzogranite); other properties such as density (2.70 to 3.06 g/cm³), porosity (19 to 23%) and water absorption (12 to 15%) demonstrated the structural compactness and durability of the samples studied. Additionally, the mechanical properties of all of the samples were extremely high, and included: (a) the unconfined compressive strength ranged from 89.28 to 240.20 MPa; (b) the engineering modulus ranged from 40.6 to 66.5 GPa; (c) the Brazilian tensile strength ranged from 7.4 to 15.2 MPa; and (d) the flexural strength ranged from 9.3 to 16.4 MPa. The shielding effectiveness against gamma rays was rated over a wide range of photon energies (0.015–15 MeV) via Phy-X/PSD and experimentally using NaI (Tl) spectroscopy at specific gamma photon energies 0.662 MeV, 1.173 MeV and 1.332 MeV. The experimental measurements of gamma-ray attenuation were validated with Phy-X/PSD calculations, with the average variation being 5.8% and no single variation over 10%, and therefore, reliability has been successfully demonstrated. The linear attenuation coefficients (LACs) were measured from 24.674 cm⁻¹ at 0.015 MeV to 0.065 cm⁻¹ at 15 MeV, which illustrates the dependence of gamma-ray interactions’ mechanisms on the energy of the incoming radiation. The half value layer (HVL) went from 0.028 cm to 10.621 cm and the mean free path (MFP) increased from 0.041 cm to 15.323 cm. The best measured performance properties were attributed to specimen MB3, as it had the highest radiation protective efficiency (88.58% at 0.15 MeV) and the lowest radiation transmission (72.16% at 0.09 MeV) in comparison to all of the experimental conditions considered. The high attenuation properties of MB3 were attributed to its high density and high levels of iron oxide, Fe₂O₃. The present work demonstrates that monzogranite, specifically sample MB3, provides excellent mechanical strength, as well as effective shielding from gamma radiation. Therefore, monzogranite, and particularly MB3, is a creative alternative for sustainable construction, as it provides materials that will be used for radiation shielding in nuclear, medical and industrial applications. Full article

Crystallization temperature was tuned to control the crystal structure and relaxor behavior of Na_0.5Bi_5.5Ti₄AlO₁₈ films. This established a structure–property regulation pathway, enabling controlled transitions from ferroelectric, non-ergodic relaxor to ergodic relaxor states. Precise crystallization temperature control reduced grain size, thereby increasing both bulk resistivity and breakdown strength via suppressed conduction pathways. The Na_0.5Bi_5.5Ti₄AlO₁₈ film achieves outstanding energy storage performance when crystallized at 500 °C, delivering a recoverable energy density of 49.6 J/cm³ and an energy efficiency of 73.5% at an applied electric field of 2820 kV/cm. It also exhibits excellent thermal and frequency stability. Thus, crystallization temperature control is a direct, effective lever for optimizing dielectric energy storage films. Full article

In this study, an electrochemical system for methane conversion was developed, employing Ni- and Ce-doped LaCoO₃ perovskite as the anode catalyst in an Na₂CO₃ electrolyte. Structural characterization revealed that the La_1−yCe_yCo_1−xNi_xO₃ (x = 0–0.5, y = 0–0.12) synthesized by the sol–gel method maintains the perovskite structure, but is rich in oxygen vacancies. Electrochemical studies revealed that the performance of methane activation is related to the presence of Ni(III) in the catalyst, and reactive oxygen species (•OH and HOO⁻) are provided through water oxidation reactions (WOR) in the Na₂CO₃ electrolyte. The electrocatalytic performance of the synthesized La_0.92Ce_0.08Co_0.5Ni_0.5O₃ during methane conversion was verified in an electrolysis cell, and ethanol and acetic acid were identified as the methane conversion oxygenates. Under ambient conditions, the formation rate of ethanol reached 577.0 μmol g_cat⁻¹ h⁻¹ at 0.90 V (vs. Ag/AgCl) in 0.5 mol L⁻¹ Na₂CO₃. The catalyst was found to retain structural integrity and sustain catalytic activity over multiple reaction cycles. Full article

Ceramics, as a handicraft, is the crystallization of art and science. In order to study the firing process of ceramics, improve their density, mechanical properties, viscosity, and surface tension, and enhance the surface quality of the shaft, this article uses first-principles methods to study the electronic properties of ceramic colorants Al₂O₃, Fe₂O₃, TiO₂, CaO, MgO, Na₂O, KO₂, and ceramic body SiO₂. Research has shown that these seven color-developing agents exhibit anisotropy and have stable crystal structures. The bandgap values of Al₂O₃, CaO, Fe₂O₃, KO₂, MgO, Na₂O, TiO₂, and ceramic SiO₂ are 6.325 eV, 3.654 eV, 0 eV, 0 eV, 4.731 eV, 1.972 eV, 2.18 eV and 6.002 eV, respectively. In Al₂O₃/SiO₂, Fe₂O₃/SiO₂, TiO₂/SiO₂, CaO/SiO₂, MgO/SiO₂, Na₂O/SiO₂, and KO₂/SiO₂ systems, due to the influence of the potential field in the SiO₂ system, the charge characteristics exhibit obvious interfacial and non-periodic characteristics. The research results revealed the charge transfer and distribution patterns at the interface between ceramic colorants and ceramic ligands, elucidating the influence mechanism of different colorants/embryo components on firing temperature, shrinkage rate, and finished product defects. This mechanism can be used to predict the advantages and disadvantages of alkali metals, iron, titanium, and aluminum components in raw materials, optimize low-temperature rapid firing formulas, suppress firing deformation, control pore defects, and improve the mechanical properties of finished products. It provides micro theoretical support for the industrialization, stabilization, and high-quality production of local ceramics in southwestern China. Full article

This study investigates the effect of sintering temperature on the hot-corrosion behavior of Ti-6Al-4V alloy in a molten salt environment. Samples were sintered at 800 °C, 900 °C, 1000 °C and 1100 °C, then exposed to the Na₂SO₄—25%NaCl for 300 h at 650 °C. The corrosion kinetics were evaluated by measuring the mass change in the specimens, and the results were correlated with their corresponding corrosion rates. The results show that the sintering temperature drives corrosion kinetics by influencing the sample density and grain size. The sample sintered at 900 °C shows a low corrosion rate due to its refined microstructure. This refined microstructure provides a high grain boundary density, which serves as a diffusion path and enables the formation of a dense, protective Al₂O₃–TiO₂ layer, as confirmed by XPS. In contrast, the sample sintered at 800 °C exhibits high porosity, resulting in an initial weight loss due to molten-salt penetration and evaporation of volatile metal chlorides. The samples sintered at 1000 °C and 1100 °C exhibit coarsened grains, leading to a thicker, brittle oxide layer and severe delamination, which in turn result in high corrosion rates. The results show that optimizing the sintering temperature to around 900 °C would enhance hot-corrosion resistance in salt-contaminated environments. Full article

Hydrogen peroxide fuel cells have emerged as a promising class of electrochemical energy conversion device owing to the dual redox character of H₂O₂, its liquid-phase storage, and its ability to operate in air-free environments. In this work, a dual-compartment direct H₂O₂ fuel cell using a Prussian Blue cathode and a tantalum anode, separated by a Nafion 115 proton exchange membrane, was systematically characterized and optimized with respect to electrolyte pH and ionic composition. The influence of pH on OCV was investigated independently in each compartment across the range of pH 2 to 12. In the tantalum compartment, OCV increased non-linearly with pH from 573 mV to 808 mV, driven by the enhanced electrochemical reactivity of the system under alkaline conditions. In the Prussian Blue compartment, OCV decreased from 676 mV to 199 mV with increasing pH, reflecting the instability of the material in alkaline conditions. The effect of the electrolyte ionic composition on average current density was subsequently investigated by varying the concentrations of NaCl and Dy(NO₃)₃. Increasing NaCl from 0 to 2.5 M produced an increase in current density from 0.414 mA/cm² to 0.973 mA/cm², consistent with ohmic resistance reduction through improved ionic conductivity. The addition of Dy(NO₃)₃ produced a positive response with an optimal concentration of $0.05$ M, at which current density reached 1.08 mA/cm², before declining sharply. Under the fully optimized conditions, pH 12 in the tantalum compartment, pH 2 in the Prussian Blue compartment, 0.3 M H₂O₂, 2.0 M NaCl, and 0.05 M Dy(NO₃)₃, the cell produced an OCV of 724 mV and a peak power density of 0.283 mW/cm² at a current density of 0.8 mA/cm². These results demonstrate that meaningful electrochemical performance can be achieved in a dual-compartment H₂O₂ fuel cell without the use of precious metal catalysts and highlight electrolyte engineering as an effective strategy for improving cell output in this class of device. Full article

Zeolites, both natural (e.g., clinoptilolite) and synthetic (e.g., FAU, ZSM-5), provide robust, tunable platforms for the removal of air pollutants and process-stream contaminants via adsorption and catalysis. This author-led article integrates experimental and theoretical insights on the adsorption of odorous compounds and ammonia (NH₃) and the catalytic abatement of nitrogen oxides (NOx) and nitrous oxide (N₂O), highlighting how topology, acidity, and metal speciation jointly control performance. Representative theoretical results show that adsorption on Brønsted acid sites is significantly more favorable (≈−1.1 eV for NH₃ and −0.37 eV for acetaldehyde) than on Na⁺ sites (≈0.02 eV and 1.22 eV, respectively), demonstrating the critical role of acid site distribution in adsorption selectivity. We dissect structure–function relationships encompassing pore size and connectivity, Si/Al ratio, Brønsted/Lewis site distribution, hydrophilicity/hydrophobicity, and the role of water, with emphasis on hierarchical porosity to alleviate transport limitations. Metal exchange and surface functionalization are discussed as levers to tailor adsorption strength and redox activity, supported by density functional theory (DFT) analyses and reaction pathways. We propose practical design descriptors (acid strength metrics, metal nuclearity, and confinement factors) that enable faster iteration of zeolite architecture for targeted separations and reactions. Sustainability considerations include the use of abundant natural zeolites, low-energy regeneration, stability under humid, mixed-stream conditions that minimize pressure drop and waste. The article closes with a forward look at data-guided optimization to accelerate “engineering zeolites” for durable, selective, and energy-efficient clean-air and process-intensification applications. Full article

The advancement of microelectromechanical systems (MEMS) drives the demand for multifunctional ferroelectrics that synergistically combine substantial strain with competitive energy storage capabilities. In this work, the simultaneous enhancement of electromechanical strain and energy storage properties is achieved in (1−x)(Bi_0.5Na_0.5)_0.94Ba_0.06(Ti_0.98Mn_0.02)O₃-xSrTiO₃ (0 ≤ x ≤ 0.3) ceramics by synergistically employing A-site defect engineering and the nonergodic/ergodic relaxor (NR/ER) phase boundary design. The incorporation of Sr²⁺ plays a dual role: it induces cationic disorder that expands the polarization difference (ΔP = P_max − P_r), thereby effectively boosting the recoverable energy density (W_rec). Concurrently, it stabilizes a critical NR/ER phase ratio near room temperature, which maximizes the strain while minimizing the strain hysteresis. Consequently, when x = 0.15, the optimized system delivers a large strain of 0.45% (d₃₃* = 562 pm/V) with low hysteresis (H = 10.8%). In addition, the x = 0.25 composition exhibits an enhanced W_rec of 1.06 J/cm³, a competitive energy-storage potential (W_rec/E) of 0.013 mC/cm², and a high efficiency (η) of 81% under 80 kV/cm. This work provides an effective strategy for developing multifunctional lead-free materials for integrated actuators and energy storage devices. Full article

As lithium demand surges and primary resources face depletion, lithium-bearing wastewater from urban mines has become a crucial secondary resource. For highly alkaline (pH 9–12), low-lithium (Li⁺ 0.5–5 g/L), high-sodium (Na/Li mass ratio > 30) wastewater generated from the alkaline leaching-washing of spent lithium-ion batteries in urban mining, a single-component, synergist-free extraction process employing HBL121 in sulfonated kerosene was developed, and its extraction stoichiometry, reaction mechanism, and industrial feasibility were elucidated. Saponification significantly enhanced extraction under moderate alkalinity: the saponified system achieved over 99% extraction efficiency at pH 11.0, whereas the non-saponified system required pH > 13.5 for comparable performance, thereby lowering alkali consumption by 81%. Under optimal conditions (saponification degree 40%, 30% (v/v) HBL121 and 70% (v/v) sulfonated kerosene, organic-to-aqueous phase ratio O/A = 1:1, extraction time 5 min), single-stage extraction efficiency exceeded 99%. A McCabe-Thiele diagram was used to determine the theoretical stage number for lithium stripping, showing that essentially all lithium ions can be stripped via a three-stage countercurrent process. Using 3.0 mol/L H₂SO₄ at an aqueous-to-organic phase ratio of 1:4, the stripping efficiency exceeded 99% from the loaded organic. Slope analysis, FT-IR, and ESI-MS confirmed a coordination mechanism between HBL121 and metal ions, forming a stable anionic bisphosphonate complex [LiNa₂(C₂₈H₄₄O₇P₂)]⁻, whose neutral parent form is HLiNa₂(C₂₈H₄₄O₇P₂). Full article

The Shizui Cu–Pb–Zn deposit is located in central Jilin Province. It sits at the tectonic junction between the eastern Xing’an–Mongolia Orogenic Belt (XMOB) and the northeastern North China Craton (NCC). This is the first discovered Paleozoic Cu-polymetallic deposit in the region. Our study combines detailed geological investigation with systematic fluid inclusion analysis. We analyzed samples from four distinct paragenetic stages. Analytical methods include microthermometry, laser Raman spectroscopy, and hydrogen-oxygen isotope analysis. These data constrain the source, evolution, and precipitation mechanisms of the ore-forming fluids. The results delineate a clear evolutionary path: the ore-forming fluid originated as a high-temperature (346–437 °C), high-salinity (up to 51.68 wt.% NaCl equiv.) NaCl–H₂O–CO₂ system during the early quartz-sulfide stage (Stage I, Quartz ± Arsenopyrite ± Pyrite Stage), as evidenced by the coeval presence of high-salinity S-type and CO₂-rich C-type inclusions, indicating fluid immiscibility. The fluid then evolved into a boiling, medium temperature to high temperature (262–355 °C), high-salinity NaCl–H₂O system during the later part of early quartz-sulfide stage (Stage II, Quartz-Cu Polymetallic Sulfide Stage), a transition marked by the common coexistence of liquid-rich (L-type) and vapor-rich (V-type) inclusions with similar homogenization temperatures. This phase separation (boiling) served as the primary trigger for the massive deposition of chalcopyrite, arsenopyrite, and pyrite. Subsequently, the system cooled and diluted, transforming into a medium- to low-temperature (182–275 °C), low-salinity, partially homogeneous NaCl–H₂O system in the late quartz-sulfide stage (Stage III, Quartz-Pb-Zn Polymetallic Sulfide Stage). Finally, in the quartz-carbonate stage (Stage IV, Quartz-Carbonate Stage), the fluid temperature further decreased, resulting in a low-temperature (128–211 °C), low-salinity, homogeneous NaCl–H₂O system. Hydrogen-oxygen isotope data show that the calculated δ¹⁸O_H2O values decreased from +6.6‰ to +6.7‰ in Stage I to +3.4‰ to +3.9‰ in Stage II, and further to −0.4‰ in Stage III, while the δD values shifted from −91.6‰ to −90.6‰, to −94.4‰ to −94.2‰, and finally to −95.7‰. This trend indicates that the initial magmatic fluid progressively mixed with meteoric water. The geological characteristics, spatial association with Hercynian biotite monzogranite, developed skarn alteration, and the documented fluid evolution trajectory collectively affirm that the Shizui deposit is a typical skarn-type system. The deposit shares significant similarities in mineralization conditions, age, and tectonic setting with the skarn-type Tianbaoshan Pb–Zn–Cu–Mo deposits in the western segment of the XarMoron–Changchun Metallogenic Belt (XCMB). This correlation strongly suggests that the Paleozoic XCMB extends eastward and holds considerable potential for the discovery of late Paleozoic skarn-type Cu-polymetallic deposits in its eastern part. Full article

The development of highly efficient and stable photoanodes is essential for advancing photoelectrochemical cathodic protection towards practical applications. Herein, a novel ternary sulfide heterojunction was engineered through the construction of a three-dimensional interlocked architecture of ZnIn₂S₄ on SnIn₄S₈ nanosheets via a sequential hydrothermal synthesis. This unique three-dimensional interlocked configuration creates an intimate interface and continuous charge transfer highways, effectively addressing the slow electron movement and poor interfacial contact that plague conventional photoelectrodes. Spectroscopic and electrochemical analyses verified the formation of a Type-II band alignment, which drives the directional migration of photogenerated electrons from ZnIn₂S₄ to SnIn₄S₈ under an intrinsic built-in electric field. Upon coupling with 304 stainless steel, the ZnIn₂S₄/SnIn₄S₃ heterojunction exhibited outstanding photoelectrochemical cathodic protection performance. It delivered impressive photocurrent densities of 15.22, 19.76, and 72.27 μA·cm⁻² in 3.5 wt% NaCl, 0.1 M Na₂S₂O₃, and 0.1 M Na₂S/NaOH electrolytes, respectively, along with a prominent 720 mV cathodic potential shift in the Na₂S/NaOH system. Most importantly, its good activity and stability in the scavenger-free 3.5 wt% NaCl solution and natural seawater highlight the strong practical potential of this 3D interlocked photoanode for sustainable marine metal corrosion control. Through a strategic multi-electrolyte assessment, the underlying protection mechanisms were decoupled, revealing that the synergy between the heterojunction-induced charge separation enabled by the three-dimensional interlocked structure and electrolyte-specific hole scavenging is key to the enhanced performance. Full article

The development of non-enzymatic glucose sensors for beverage analysis remains challenging due to insufficient active sites, poor conductivity, and limited stability in complex matrices. A nickel-carbon nanotube composite (Ni/CNT−600) was synthesized via in situ solvothermal deposition followed by pyrolysis at 600 °C under an inert atmosphere. The optimized Ni/CNT−600 featured uniform anchoring of Ni nanoparticles on CNTs through strong Ni–C and Ni–O–C interfacial bonds, validated by various characteristic techniques. The Ni/CNT−600 sensor exhibited exceptional sensitivity (538.48 μA mM⁻¹ cm⁻²) and an ultralow detection limit (0.003 μM) in 0.1 M NaOH at +0.65 V, surpassing many reported metal-based and enzymatic sensors. It demonstrated remarkable selectivity against key interferents (e.g., ascorbic acid, uric acid). In real beverage samples (orange juice, grape juice, cola, green tea, milk), recovery rates ranged from 95.6% to 112.8%. This work demonstrates a well-defined Ni-CNT synergistic interface that contributes to enhanced non-enzymatic glucose sensing performance, effectively addressing matrix complexity in beverages. Full article

This work describes the fabrication and characterization of a novel lateral 4H-SiC PiN diode featuring inter-device isolation technology for power integrated circuits (ICs). The device’s architecture includes thick SiO₂ blocking layers and inter-device trench isolation structures, enabling effective electrical isolation between power devices and control circuitry on a single chip. The devices demonstrate good isolation performance, with inter-device leakage currents below 5 nA at a reverse bias of 200 V. The diodes keep reverse leakage current low (<1 μA at 20 V), but exhibit non-distinct turn-on behavior. This is mostly due to the too-shallow N+ and P+ ion implantation region and high series resistance. A monolithically integrated bridge circuit operating at 50 Hz and 200 Hz validates the integration approach; however, large forward voltage drops show that the high series resistance at the device level affects overall conversion efficiency. The transfer length method (TLM) characterization reveals high sheet and contact resistances, which are responsible for the conduction limitations in the PiN diode forward performance. This study establishes the foundation for a lateral SiC device technology with promising inter-device isolation capabilities, as well as the bridge circuit built based on the lateral PiN diodes, which shows the potential of this technology for future monolithic power IC applications. Full article