Search Results (825)

Conventional 8YSZ thermal barrier ceramics suffer from limited phase stability and insufficient infrared radiation regulation at high temperatures. Sc₂O₃ doping can reduce thermal conductivity and improve phase stability, but the improvement remains limited because the fixed-valence substitution of Sc³⁺ cannot effectively increase defect concentration or regulate carrier behavior. In this work, CeO₂ with tunable valence states was incorporated into the Sc-stabilized YSZ system to realize the synergistic modulation of lattice thermal conductivity and photon thermal conductivity. A series of Sc₂O₃–CeO₂ co-doped YSZ ceramics were fabricated via solid-state sintering, and the effects of co-doping on phase structure, defect evolution, thermal conductivity, infrared emissivity, and bandgap characteristics were systematically investigated. The results show that all co-doped samples maintained a stable tetragonal fluorite structure with relative densities higher than 96%. Among them, Sc_0.08Ce_0.005Y_0.005Zr_0.91O₂ exhibited the best comprehensive performance. Its thermal conductivity at 1000 °C reached 2.073 W·m⁻¹·K⁻¹, which was 11.9% lower than that of conventional 8YSZ. Meanwhile, the average infrared emissivity in the 3–5 μm band increased to 0.779. XPS analysis indicated that Ce incorporation promoted oxygen-vacancy formation, which enhanced phonon scattering and reduced lattice thermal conductivity. In addition, co-doping narrowed the band gap and facilitated carrier excitation, thereby strengthening infrared absorption and emission behavior. The enhanced infrared emissivity further contributed to the suppression of radiative thermal transport at elevated temperatures. This work demonstrates that Sc₂O₃–CeO₂ co-doping provides an effective strategy for simultaneously regulating phonon transport and photon transport in YSZ-based ceramics. The results provide new insight into the design of advanced thermal barrier materials with low thermal conductivity and enhanced high-temperature infrared radiation performance. Full article

As an emerging photovoltaic technology, Cu₂ZnSn(S,Se)₄ (CZTSSe) thin-film solar cells are regarded as a viable, cost-effective alternative to satisfy future demand for green energy. This promise is attributed to their tunable bandgap (1.0~1.5 eV), high absorption coefficient (>10⁴ cm⁻¹), and environmentally friendly composition. Currently, the record power conversion efficiency (PCE) of CZTSSe devices has reached 16.6%, approaching commercial levels. However, this value remains significantly lower than its theoretical limit of 32.8% and the 23.6% achieved by the homologous CIGS technology, indicating immense potential for performance enhancement. The severe open-circuit voltage deficit (E_g/q-V_oc) remains a critical factor preventing CZTSSe solar cells from reaching their expected efficiency. This issue is primarily associated with band misalignment and deep-level defects at the interfaces. At present, interface engineering has been demonstrated to be an effective strategy to significantly improve the performance of CZTSSe thin-film solar cells. Herein, we review the development process of CZTSSe photovoltaics, systematically discuss existing interface-related issues and comprehensively summarize recent strategies in interface engineering. Finally, to further elucidate the intrinsic mechanisms and facilitate the development of high-efficiency devices, future research directions and perspectives regarding interface engineering are proposed. Full article

Under the “dual carbon” goals, Taiyuan, a prefecture-level administrative unit and energy-intensive region in Shanxi Province, China, has experienced changes in soil carbon storage and soil carbon flux under rapid urbanization and industrialization. To clarify the spatial patterns of soil carbon storage and flux, 26 field sampling sites, including 78 soil samples, were analyzed using laboratory measurements and an optimized tunable diode laser absorption spectroscopy–geographic information system (TDLAS–GIS) integrated monitoring approach. This study investigated the spatial patterns of soil carbon storage and flux and discussed their potentially associated factors, providing an exploratory workflow for regional carbon monitoring. The results showed clear spatial heterogeneity, with an average soil organic carbon (SOC) content of 10.86 g/kg. High-SOC areas were mainly located in the southern and southwestern plains, while lower SOC levels occurred in urban expansion zones and highly disturbed surfaces. The western mountainous areas were important ecological barriers but were not the highest measured SOC zones. At the site level, arable land and forestland showed higher mean SOC values than grassland, with average SOC contents of 12.47, 12.07, and 8.27 g/kg, respectively, although these land-use-related differences were not statistically significant. Soil carbon flux was relatively higher in some mountainous regions and industrial–ecological transition areas but lower in several urban expansion areas. The results suggest that urbanization and industrial activity may be associated with changes in SOC and soil-atmosphere CO₂ exchange. This study describes the spatial variation characteristics of soil carbon storage and flux, establishes a reproducible TDLAS–GIS workflow for regional carbon monitoring, and provides exploratory support for ecological sustainability, sustainable land management, and the “dual carbon” strategy in northern resource-based cities. Full article

Two-dimensional (2D) materials have emerged as a key platform for next-generation electronics due to their atomic thickness and tunable properties. Iron disulfide (FeS₂), known as pyrite, with a bandgap of ~0.95 eV, is suitable for solar energy applications. However, its performance is limited by defects in bulk crystals. Reducing FeS₂ to a single layer eliminates bulk defects and enables strain engineering of the bandgap. In this study, First-principles density functional theory (DFT) calculations are performed using the CASTEP code and the PBEsol functional to examine the structural, electronic, and optical properties of a distorted 1T′-phase FeS₂ monolayer. Full geometry optimization yields lattice parameters a′ = 17.594 Å, b′ = 3.20231 Å, c′ = 5.28091 Å, and Fe–S bond angles of ~75.8° and ~98.2°, confirming symmetry-breaking distortion. The monolayer is dynamically stable, showing no imaginary modes in the phonon dispersion, and remains structurally intact up to 1000 K in molecular dynamics simulations. The unstrained system has an indirect bandgap of 0.70 eV, with the valence band maximum at the Γ point (dominated by S-p states) and conduction band minimum near the X point (Fe-d states). Under mechanical strain (±4%), the bandgap decreases significantly: from 0.70 eV to 0.44 eV under +4% tensile strain along the y-axis, and to 0.53 eV under −4% compressive strain. Biaxial strain causes weaker modulation, reducing the gap to 0.66 eV (+4%) and 0.62 eV (−4%). Optical absorption exceeds 10⁴ cm⁻¹ for photon energies above the bandgap, with tensile strain causing redshifts and compressive strain inducing blueshifts. These findings demonstrate that 2D FeS₂ is mechanically robust, electronically tunable, and optically active, making it a promising candidate material for flexible strain sensors and photovoltaic devices. This work is intended to motivate and inform future synthesis efforts. Full article

In cold, humid environments, even a small amount of ice accumulation on the blade surface can degrade aerodynamic performance, increase drag, induce premature stall and vibration, and raise the risks of shutdown, fatigue, and ice throw. Existing blade anti-icing and de-icing strategies (such as passive coatings, electrothermal heating, hot-air systems, and hybrid designs) struggle to simultaneously meet the requirements of lightweight construction, low-voltage rapid heating, conformability to curved surfaces, erosion resistance, long-term durability, and scalable manufacturing. MXenes, particularly Ti₃C₂T_x, have attracted attention due to their high electrical conductivity, broadband optical absorption, solution processability, tunable interfacial chemistry, and good compatibility with polymer matrices. However, their oxidation issue and blade-scale deployment challenges (coating chemistry, scalable fabrication, real-world testing) remain obstacles. Based on this, this review discusses Ti₃C₂T_x-based anti-icing, de-icing, and defogging strategies for wind turbine blades, with emphasis on material properties, functional mechanisms, coating architectures, fabrication routes, durability, and scalability, and highlights their potential for lightweight and energy-efficient all-weather blade protection. Finally, future research directions for Ti₃C₂T_x-based blade anti-icing and de-icing are prospected. This review not only aims to identify key knowledge gaps in current research but also strives to provide a theoretical reference for the application of Ti₃C₂T_x in the complex service environment of real wind turbine blades, thereby moving beyond idealized laboratory conditions. Full article

Reconfigurable photonic metasurfaces enable tunable thermal-emission engineering in the long-wave infrared (LWIR), particularly within the 8–13 μm atmospheric window. This work includes the investigation on a concentric-ring VO₂/SiO₂/Au metasurface for LWIR spectral-emissivity modulation. Full-wave simulations showed that, in the metallic phase (σ = 2 × 10⁵ S/m where σ is conductivity), the structure exhibited an absorption over 90% across the 9.3–15 μm sub-band, with two near-unity resonances near 10.2 and 13.3 μm. Control structures, gap-dependent spectra, E-field maps, and current-density Cartesian multipole decomposition supported a hybridized-ring mechanism in which both dominant resonances were predominantly electric-dipole-like ring branches whose spectral positions and field localizations were modified by inter-ring coupling. Across the conductivity sweep, the normal-incidence band-averaged 8–13 μm emissivity changed from 0.0184 to 0.8844, corresponding to a switching ratio of 48.06. The four-fold symmetry of unit cell also yielded polarization-insensitive and angularly robust LWIR absorption, while the simplified endpoint thermal-balance estimate indicated a metallic-state net cooling power of 49.3 W m⁻² at T = T_amb = 300 K, where T_amb was the ambient temperature, and an estimated equilibrium temperature drop of 4.4 K below the ambient for the metallic-state endpoint, whereas the insulating-state one suppressed this response. These results identify concentric VO₂ ring metasurfaces as promising candidates for switchable LWIR thermal-emission control. Full article

Strong chiral responses in planar dielectric metasurfaces are important for polarization-selective nanophotonic devices, but achieving large and reversible circular dichroism (CD) in simple dielectric structures remains challenging. This work proposes a symmetry-broken silicon metasurface that realizes near-infrared chiral response based on bound states in the continuum (BICs). The unit cell consists of a silicon nanoblock with two through-air grooves. The in-plane displacement of the air grooves breaks the C₂ rotational symmetry and splits the BIC-related polarization singularity into two circularly polarized points (C points) with opposite handedness. By further introducing out-of-plane tilting, one of the C points is shifted to the Г point, enabling spin-selective coupling between normally incident circularly polarized light and the quasi-BIC mode. Reversing the out-of-plane tilt switches the sign of CD, with values reaching −0.98 and 0.98, approaching the theoretical limits of ±1. Under oblique incidence, the structure can also exhibit near-limit CD responses. Finally, by introducing graphene, the structure achieves tunable circular-polarization-selective absorption, with the absorption of CD approaching the theoretical limits of ±0.5 for the coupled system. This work provides a new design idea for compact chiral nanophotonic materials by using symmetry breaking to control spin-selective quasi-BIC coupling and tunable chiral absorption. Full article

Graphene–plasmonic electro–optic (EO) modulators have attracted significant interest for compact and energy-efficient integrated photonic systems due to their electrically tunable optical response and strong light–matter interaction. In this work, an ultra-thin silicon-on-insulator (SOI) graphene–plasmonic slot modulator (G-PSM) is investigated using a combined semi-analytical and numerical framework. The analysis integrates finite-temperature Kubo conductivity modeling, perturbation-based effective-index analysis, overlap-factor evaluation, eigenmode analysis, and full-wave simulations to study the influence of silicon thickness on the EO performance of the proposed structure. The obtained results demonstrate that geometry engineering strongly affects modal confinement, overlap enhancement, effective-index perturbation, transmission characteristics, extinction ratio (ER), insertion loss (IL), energy-per-bit consumption, and EO bandwidth. Under optimized operating conditions, the proposed G-PSM achieves an effective refractive-index variation of approximately $3.1\times {10}^{-3}$, an ER of approximately 3.5 dB, an IL of 1.5–2 dB, an energy-per-bit consumption of approximately 7.5 fJ/bit, and a 3 dB EO bandwidth approaching 200 GHz. Strong electromagnetic confinement is achieved inside the plasmonic slot region near the graphene-active layer, enabling efficient electro–absorptive and electro–refractive modulation. Excellent agreement between the semi-analytical calculations and numerical simulations validates the developed framework and confirms the suitability of the proposed ultra-thin SOI G-PSM for compact broadband EO modulation in future integrated photonic systems. Full article

Organic–inorganic hybrid metal halides (OIMHs), especially zero-dimensional (0D) ones, have been recognized as an excellent class of luminescent materials due to their structural diversity and tunable emission properties. In this work, using the environmentally friendly Zn(II) ion as the central metal and 1,4,7,10-tetraazacyclododecane (Cyclen) as the organic component, we successfully synthesized a novel OIMH, (H₃Cyclen)(ZnBr₄)·Br·H₂O. Single-crystal X-ray diffraction analysis reveals that (H₃Cyclen)(ZnBr₄)·Br·H₂O possesses a 0D structure, in which the [ZnBr₄]²⁻ tetrahedra are uniformly separated by the organic amine cations. This structural feature is expected to enhance the material’s stability and optimize its optoelectronic properties. Under UV lamp irradiation, (H₃Cyclen)(ZnBr₄)·Br·H₂O emits bright blue-green light. Therefore, we systematically investigated its luminescence properties. The emission mechanism was further elucidated using UV–vis absorption spectroscopy and DFT calculations. Finally, (H₃Cyclen)(ZnBr₄)·Br·H₂O was employed as a luminescent material to fabricate a white light-emitting diode (WLED), demonstrating its potential as an excellent phosphor material. Full article

Passively mode-locked lasers, as essential tools for generating ultrashort pulses, have found widespread applications in industrial manufacturing, optical communications, biomedical imaging, and fundamental scientific research. Saturable absorbers serve as the key components governing the performance of such laser systems. Conventional saturable absorber materials, including semiconductor saturable absorber mirrors, carbon nanotubes, and graphene, however, suffer from inherent limitations in operational wavelength range, damage threshold, and environmental stability. In recent years, two-dimensional transition metal carbides and nitrides, known as MXenes, have emerged as a promising class of materials to address these challenges. Their unique metallic conductivity, broadband saturable absorption, ultrafast carrier dynamics, excellent thermal management capability, and versatile chemical tunability offer unprecedented opportunities for advanced saturable absorber applications. This review systematically summarizes the recent progress of MXene-based saturable absorbers, with an emphasis on their distinctive advantages in extending the mode-locked wavelength range, enhancing output pulse stability, and increasing the optical damage threshold. Furthermore, strategies for performance optimization through surface terminal group engineering, defect modulation, and heterostructure design are discussed in depth. Finally, the future prospects and key challenges toward industrial implementation of MXenes in ultrafast photonics are outlined, aiming to stimulate further advancements in high-performance ultrafast laser technology. Full article

Metasurface absorbers play a critical role in microwave electromagnetic control, yet conventional designs suffer from fixed performance and strong cross-coupling between tunable parameters, limiting their adaptability in dynamic environments. Here, we propose a dual-band reconfigurable metasurface absorber with independent modulation of absorption intensity and frequency. The absorber adopts a double-layer metallic structure integrated with PIN diodes and varactors, realizing independent regulation of absorption intensity and frequency. In the lower band (4.1–7.7 GHz, S₁₁ < −10 dB), the absorption intensity is continuously tunable via the PIN diode bias without frequency shift, while in the upper band (13.4–14.4 GHz), the absorption frequency is continuously tunable via the varactor bias without intensity variation. Quantitative cross-sensitivity analysis yields a frequency shift of less than 1.5% during intensity tuning and an intensity variation of less than 0.8 dB during frequency tuning. The absorber exhibits polarization insensitivity and stable performance under oblique incidence up to 45°. An equivalent circuit model is developed and validated against full-wave simulations. Numerical analyses of fabrication tolerance for the active components confirm that the highly decoupled behavior is robust, with absorption peak shifts below 0.15 GHz and intensity variations below ±1.2 dB. Our conceptual design highlights the potential towards independent multi-parametric control in reconfigurable metasurface absorbers for adaptive electromagnetic shielding, smart radomes, and frequency-agile sensing. Full article

The increasing global demand for renewable energy has intensified the search for high-efficiency and cost-effective solar cell technologies. Quantum dot-sensitized solar cells (QDSSCs) have emerged as promising candidates due to their tunable optoelectronic properties and enhanced light absorption. In this study, SnS quantum dots were synthesized from dithiocarbamate complexes using different ligands, namely m-toluidine (SnS1), aniline (SnS2), and p-toluidine (SnS3), to investigate the influence of precursor chemistry on material properties and device performance. Structural analysis confirmed the formation of an orthorhombic phase for all samples, while morphological studies revealed well-dispersed nanocrystals for SnS1 (5.93 nm), increased aggregation for SnS2 (8.57 nm), and partially fused domains with an intermediate size for SnS3 (6.67 nm). Optical measurements showed bandgap energies of 2.8, 2.2, and 2.7 eV for SnS1, SnS2, and SnS3, respectively, with SnS3 exhibiting reduced charge-recombination behaviour. Photovoltaic devices fabricated using these materials yielded power conversion efficiencies of 3.40, 2.03, and 7.63% for SnS1, SnS2, and SnS3, respectively, with no significant improvement observed for bifacial configurations. The superior performance of SnS3 is attributed to an optimal balance between light absorption, morphology, and charge transport properties, highlighting the critical role of precursor ligand selection in tuning quantum dot characteristics for improved QDSSC performance. Full article

This study presents a comprehensive first-principles investigation of the structural, elastic, electronic, and optical behavior of cubic CsCaF₃ under hydrostatic pressure. The material is confirmed to be a stable Pm-3m fluoride perovskite, with a lattice constant of $4.496 \AA$ and a tolerance factor of $0.902$. At ambient conditions, CsCaF₃ exhibits high intrinsic stiffness ($C_{11}=107.88 \mathrm{G}\mathrm{P}\mathrm{a}$, $B=53.07 \mathrm{G}\mathrm{P}\mathrm{a}$, $G=29.16 \mathrm{G}\mathrm{P}\mathrm{a}$, $E=73.94 \mathrm{G}\mathrm{P}\mathrm{a}$) and maintains mechanical stability while becoming progressively stiffer under compression. The electronic structure reveals a wide indirect band gap of $7.1 \mathrm{e}\mathrm{V}$ that broadens to $8.43 \mathrm{e}\mathrm{V}$ and transforms into a direct gap at elevated pressures. Optical calculations show strong transparency in the visible range, with a low refractive index ($1.58$) and reflectivity ($~5\%$), and a deep-UV absorption edge near $6 \mathrm{e}\mathrm{V}$. Pressure enhances these features, increasing the refractive index to 1.66 and the maximum reflectivity to 45.87% at $24 \mathrm{G}\mathrm{P}\mathrm{a}$. The plasmon resonance also displays pronounced tunability, blue-shifting from $29.56$ to $30.79 \mathrm{e}\mathrm{V}$ with a fourfold rise in intensity. Analysis of the effective-electron number further indicates pressure-driven redistribution of spectral weight within the UV region. Together, these findings demonstrate that CsCaF₃ combines robust structural stability with highly pressure-tunable optical and plasmonic responses, positioning it as a promising candidate for deep-UV optoelectronics, photonic coatings, and pressure-responsive optical technologies. Full article

The global transition from petrochemical to sustainable bio-based plastics has been strongly supported by electrospinning (ES), a versatile nanotechnology enabling the fabrication of ultrathin fibers with multifunctional properties. The solution ES process alongside the uniform fibers, a characteristic “beads-on-string” morphology, consisting of alternating cylindrical and spindle-like segments, is frequently observed. Once considered undesirable, these structures are now recognized as functional fibrous architectures with enhanced properties. This work explores the valorization of beaded fibers through combined experimental characterization and modeling, aiming to evaluate the impact of beading on drug diffusion and delivery performance. Poly(3-hydroxybutyrate) (PHB) was selected as the model biopolyester and dipyridamole (DPD) as the model drug. Ultrathin fibers were fabricated using the laboratory electrospinning device, EFV-1 (ICP, Moscow, Russia). The distance between the capillary nozzle and the anodic collector was set to 180 mm, with the capillary tip radius equal to 0.35 mm, and applied voltage between the electrodes was kept constant at 18 kV. Drug release profiles were obtained by simulating DPD diffusion in ellipsoidal (beads) and cylindrical fiber domains. Ultrathin fibers were fabricated by solution electrospinning under environmental conditions (at ambient temperature, 50% relative humidity). Morphology was analyzed via SEM, thermal properties via DSC, and structure via FTIR spectroscopy at different temperatures, including the melting point (~170 °C). Drug release kinetics were monitored using a UV-Vis spectroscopy. The impact of DPD diffusion within the ellipsoidal and cylindrical constituents of polymer filaments was considered to modulate release profiles for the development of innovative pharmaceutical platforms. Diffusion controlled drug release was computationally modeled using a specially designed simulation program, in good agreement with experimental data. The results demonstrate that morphological parameters significantly affect diffusion and release kinetics. The controlled exploitation of bead-on-string architectures may enable the design of electrospun materials with tunable absorption of pollutant filtration, mechanical performance, and flexibility in drug release profiles, for sustainable biopolymers like PHB. Full article

Polymer–liquid crystal (polymer–LC) composites enable electrically tunable optical modulation through the coupling of molecular anisotropy and polymer-induced stabilization. However, most dual-cell LC architectures that independently control absorption and scattering rely on four substrates and multiple independently driven electrode layers, resulting in increased fabrication complexity. In this work, a dual-cell polymer–LC device employing a simplified asymmetric electrode architecture is demonstrated to achieve independent control of absorption and scattering within a three-substrate configuration. The device integrates a dye-doped vertically aligned super-twisted nematic (DDVSTN) cell for absorption-based modulation and a reverse-mode polymer-stabilized cholesteric texture (PSCT) cell for electrically induced scattering. The PSCT layer is driven by interdigitated electrodes on the bottom substrate, while the DDVSTN layer is driven by vertical electric fields, preserving electrical decoupling between the two cells. Four distinct optical states—clear, tinted, private, and tinted-private—are achieved through selective voltage addressing. Spectral measurements confirm stable four-state optical modulation with transmittance varying from approximately 60% in the clear state to about 13% in the tinted-private state. The proposed architecture reduces electrode-layer complexity while maintaining independent optical control, providing a fabrication-efficient platform for smart window systems and polymer–LC photonic devices. Full article