Search Results (4,641)

Corrosion-protective coatings have progressed from passive barrier systems and chromate-based technologies toward multifunctional materials that integrate barrier durability, interfacial adhesion, active inhibition, electrochemical response, and self-healing capabilities. However, the intellectual framework connecting these technological developments remains fragmented, as most reviews focus on specific material families rather than on the broader evolution of the field. This study examines technological paradigms in corrosion-protective coatings through a citation network analysis of highly cited publications retrieved from Web of Science and processed with CitNetExplorer. The most influential publications were thematically reviewed to identify dominant materials, coating architectures, protection mechanisms, seminal contributions, and bridge articles. Four principal paradigms were identified: smart and self-healing coatings based on nanocontainers, layered double hydroxides, mesoporous silica, halloysite, zeolites, hydroxyapatite reservoirs, and microcapsules; chromate-free sol–gel and silane pretreatments based on organic–inorganic hybrid matrices, organosilanes, rare-earth inhibitors, and oxide nanoparticles; graphene and graphene oxide-based nanocomposite coatings in which two-dimensional fillers enhance tortuosity, reduce water uptake, and reinforce polymer matrices and coating–substrate interfaces; and electroactive coatings based mainly on polyaniline and polypyrrole, where protection is associated with passivation, redox mediation, and dopant-controlled inhibition. The findings indicate that corrosion-protective coatings have evolved through partially overlapping and increasingly integrated paradigms rather than through a single technological trajectory. This citation network analysis clarifies the transition from chromate replacement toward active, nanostructured, electroactive, and self-healing corrosion-protective systems. Full article

Yttrium is one of the lesser-known critical elements, but it has recently gained significant market attention due to a dramatic price increase of up to 1400% in Europe. Although its primary application is in phosphors (e.g., in LEDs), modern society heavily depends on these technologies, making yttrium indispensable. However, the limited availability of yttrium raises concerns about its long-term supply. Therefore, there is a need for efficient techniques to recover yttrium from secondary materials to ensure a stable supply. While the wastes contain only trace amounts of yttrium and often have complex elemental compositions, they are more readily available than primary sources. The yttrium content ranges from a few percent in spent phosphors to several hundred ppm in red mud, around a few dozen ppm in phosphogypsum, and up to several ppm in coal and coal fly ashes. Although conventional hydrometallurgical methods are commonly used, they lack selectivity for yttrium recovery. In contrast, unconventional solvometallurgical and bioleaching approaches currently play a relatively minor role in recovery applications. This review discusses a range of methods investigated for yttrium recovery from different types of secondary resources, including pretreatment (where applicable), leaching, and subsequent yttrium recovery from the resulting leachates. Although the chemical and phase compositions of yttrium-bearing waste materials differ substantially, necessitating tailored treatment strategies, acid leaching remains the predominant extraction route and is most commonly followed by solvent extraction and/or oxalate precipitation. Most studies reported to date have been conducted at the laboratory scale. Despite progress and the development of promising recovery concepts, the efficient separation of high-purity yttrium from other rare earth elements and co-existing impurities continues to represent the key obstacle to commercial-scale application. Full article

Rare-earth vanadates constitute an important class of functional materials with potential applications as luminophores, in optoelectronics and catalysis. The research for this work was inspired by the incomplete literature data, including the synthesis, structure and physicochemical properties of europium(III) vanadate(V) with the general formula Eu₅VO₁₀. The primary goal of this work was to supplement the missing data about this compound and identify its potential applications. This compound was synthesized using three methods, including waste-free methods: ceramic, mechanochemical and a modified Pechini method. The obtained Eu₅VO₁₀ was characterized using XRD, DTA–TG, FTIR, UV–Vis–DRS, SEM and gas pycnometry. It was settled that Eu₅VO₁₀ crystallizes in the monoclinic system and is thermally stable up to a temperature of approximately 1310 °C, above which it decomposes in the solid phase. Estimated energy gap (E_g) values ranged from ~3.21 eV to ~3.53 eV depending on the synthesis method used, allowing Eu₅VO₁₀ to be classified as a wide-bandgap electrical semiconductor. The results also showed that the synthesis method affects the crystallite size of the synthesized compound. The development of synthesis methods and characterization of Eu₅VO₁₀ expands our understanding of rare-earth vanadates and their potential applications as functional materials. Full article

YBO₃:Eu³⁺ phosphors are regarded as strong candidates for high-performance luminescent materials owing to their excellent luminescence efficiency. In this study, novel YBO₃:Eu³⁺ porous/hollow microspheres were synthesized via a simple, continuous ultrasonic spray pyrolysis (USP) process using different organic additives. XRD analysis confirms that all samples crystallize in a pure hexagonal YBO₃ phase, indicating that the additives do not affect phase formation. Electron microscopy reveals a clear morphological evolution from solid to porous and hollow microspheres, with tunable shell thickness and cavity size. Compared with solid microspheres, the obtained hollow microspheres significantly reduce the consumption of rare earth materials with minimal influence on luminescence properties. The results suggest that hollow microspheres are promising substitutes for solid microspheres in the field of rare earth phosphors and the ultrasonic spray pyrolysis (USP) approach shows great potential in large-scale synthesis of morphology-controllable microspheres. Full article

In this study, we examined the mineralogy, geochemistry and origin of Fe–Mn mineralization occurring as lenses within siliceous mudstones of the Middle Eocene Maden Complex (Durmuştepe, Elazığ, Türkiye) using multivariate statistical methods and Compositional Data Analysis (CoDA). Major-oxide, trace-element and REE analyses were performed on 21 samples (n = 21), comprising 11 ore and 10 host-rock samples. Ore microscopy, discrimination diagrams, PAAS-normalized REE patterns, Principal Component Analysis (PCA), Hierarchical Cluster Analysis (HCA), factor analysis, Kendall correlation and CLR-transformed CoDA-PCA were applied. The ore consists of pyrolusite, braunite, manganite, magnetite and hematite. Massive and felty textures indicate rapid precipitation linked to abrupt physicochemical changes near the vents. Fe/Mn ≈ 1.62 and Co/Ni = 0.03–0.04 support an exhalative origin; Ce/Ce* = 0.10–0.15 (mean 0.11) records a pronounced negative Ce anomaly; and Eu/Eu* = 1.06–1.18 suggests vent-fluid temperatures below ~250 °C. CoDA-PCA shows that Ce is decoupled from the other lanthanides; HCA separates ore from host-rock populations; and factor analysis indicates that Ti–Al–K detrital input diluted ore accumulation. Integrating these results, we interpret Durmuştepe as a proximal volcano-sedimentary hydrothermal-exhalative Fe–Mn system that formed during magmatism in the Maden marginal basin under oxic seawater mixing and contemporaneous detrital sedimentation. The multivariate workflow also provides a reproducible approach for source characterization in similar mixed-origin deposits. Full article

High-velocity oxy-fuel (HVOF) spraying was used to deposit WC-Co and WC-Co-Cr coatings on high-speed steel in order to determine how binder chemistry and coating thickness jointly control load support, friction, and dry sliding wear resistance. Nominal 50 and 100 µm coatings were compared within the same substrate framework by XRD, FT-IR, SEM/EDX, cross-sectional image analysis, Vickers hardness testing, dry sliding wear testing, and post-wear SEM/EDX. The coatings retained WC as the dominant crystalline phase, while weak overlapping features were associated with binder-rich regions and limited decarburization products. Cross-sectional observations confirmed continuous coating build-up close to the nominal thicknesses and low apparent dark-feature/porosity fractions. All WC-based coatings increased the effective hardness and reduced mass loss relative to uncoated HSS. Among the tested conditions, WC-Co-Cr-100 provided the highest effective hardness and the lowest mass loss after 1000 m sliding, whereas WC-Co-100 produced the lowest mean coefficient of friction. The results show that low friction and high wear resistance are not governed by identical mechanisms: WC-Co favours interfacial shear reduction, while the thicker Cr-containing coating provides superior resistance to material removal through improved carbide retention, binder stability, and coating-scale load support. Full article

Marine source rocks in the Tarim Basin are generally highly mature to overmature, and conventional organic geochemical parameters may not fully reflect their original organic matter accumulation under such conditions. In this study, a comprehensive dataset including major elements, trace elements, and rare earth elements was used to systematically evaluate paleoproductivity variations, spatial distribution patterns, and geochemical controls of the Lower Cambrian (Є1) source rocks in the Tarim Basin. The results show that paleoproductivity in the Lower Cambrian source rocks exhibits clear stratigraphic and regional differentiation. Vertically, the lower intervals are characterized by relatively higher paleoproductivity, whereas the overlying intervals show a gradual decrease in productivity-related signals. Spatially, paleoproductivity in northwestern Tarim was generally higher and more variable than that in eastern Tarim, reflecting differences in depositional environments and material supply among different parts of the basin. These variations were jointly controlled by basin paleogeography, redox conditions, hydrothermal input, and terrigenous supply. Further analysis indicates that inorganic elements can provide complementary information on nutrient supply, export productivity, and organic matter preservation. Among these proxies, P and Ba and their excess indicators record enhanced nutrient availability and increased organic matter export, respectively; however, their variations may be decoupled from TOC because they are strongly influenced by redox conditions and post-depositional processes. In contrast, Ni, Cu, and Zn show relatively weaker enrichment but may better reflect the preserved organic matter component under reducing conditions. This study emphasizes that the application of inorganic geochemical proxies to highly mature marine source rocks requires integrated consideration of lithological heterogeneity, redox conditions, hydrothermal influence, terrigenous input, and diagenetic modification. This work represents a quantitative, data-based review and statistical reanalysis of published geochemical datasets. Full article

This review focuses on the effects of trace and residual rare-earth elements on inclusion evolution and Nb–Ti–V precipitation behavior in microalloyed steels. Existing studies indicate that trace rare-earth elements can transform conventional Al₂O₃- and MnS-type inclusions into rare-earth oxides, oxysulfides, and sulfides, while also modifying local interfacial states and solute distributions through segregation and interfacial activity. These changes further affect the nucleation sites, growth behavior, coarsening tendency, and spatial distribution of NbC, TiN, VC, and related carbonitrides. To explain the seemingly contradictory precipitation responses reported in the literature, this review examines rare-earth effects from the perspectives of inclusion inheritance, heterogeneous nucleation, interfacial energy modification, local solute redistribution, and thermomechanical processing history. The available evidence suggests that the metallurgical role of trace rare-earth elements cannot be attributed solely to inclusion modification. Instead, their effects arise from the combined influence of inclusion evolution, interfacial activity, local chemical heterogeneity, and precipitation kinetics under specific processing conditions. These insights provide practical guidance for alloy and process design by linking rare-earth addition, inclusion control, and Nb–Ti–V precipitation regulation in microalloyed steels. Full article

Layered cloud cover (LCC) describes the vertical distribution of cloud occurrence and is a key variable for assessing the radiation budget of the Earth-atmosphere system. However, ground-based radars have limited spatial coverage, while existing satellite cloud-cover products rarely provide both spatiotemporal continuity and high accuracy. Because nighttime satellite observations lack visible-channel information, conventional passive satellite remote sensing remains limited in providing day-night continuous LCC retrievals. In this study, we propose an infrared-based framework for retrieving large-scale day-night LCC from geostationary satellite observations. The framework first resolves cloud vertical structure using a hybrid machine learning and physical algorithm for day-night cloud-base height (CBH) retrieval, and then derives cloud cover in different vertical layers. Validation against active measurements from spaceborne and ground-based cloud radar demonstrates that the satellite-retrieved LCC captures cloud vertical distributions and their diurnal variations. The cloud-layer identification accuracies reach 76.3% and 77.9% for daytime and nighttime, respectively, with corresponding Cohen’s kappa coefficients of 0.66 and 0.68. The primary source of algorithmic uncertainty is the low precision of low-cloud identification, which is constrained by objective factors and physical characteristics. The retrieved annual mean LCC fields reproduce major climatological features, including enhanced high and deep convective clouds over the tropical western Pacific and dominant low-cloud occurrence over the mid-latitude oceans. A case study of Typhoon Doksuri further shows that the 10 min LCC retrievals capture the vertical evolution of the typhoon cloud system during intensification, eyewall structural adjustment, landfall, and post-landfall decay. These results indicate that the proposed infrared-based retrieval framework provides a promising basis for constructing large-scale day-night LCC datasets and can support cloud-radiation studies, climate-model evaluation, and weather monitoring. Full article

The structural, electronic, and magnetic properties of the PdRSb, usually also referred to as RPdSb, ($R=$ La-Lu) semi-Heusler compound series have been systematically investigated using first-principles calculations based on Density Functional Theory (DFT). Our structural optimizations reveal that the cubic $C{1}_{\mathrm{b}}$ A-type variant is the energetically most favorable and thermodynamically stable ground state across the entire series. The calculated equilibrium lattice constants follow the well-known lanthanide contraction trend, with the exception of the Yb-based compound, which displays an anomalous lattice expansion. Magnetic stability analysis demonstrates that the magnetism is highly localized at the rare-earth (R) sites and closely follows the progressive filling of the $4f$ shell, peaking at $7{\mathsf{\mu }}_{\mathrm{B}}$ for PdGdSb, while PdLaSb, PdYbSb, and PdLuSb remain non-magnetic. Furthermore, our electronic structure calculations reveal a rich variety of behaviors: PdLaSb and PdLuSb behave as gapless semiconductors, while most of the magnetic compounds exhibit near half-metallic characteristics. Notably, PdCeSb is predicted to be a perfect half-metal with an integer magnetic moment of $1{\mathsf{\mu }}_{\mathrm{B}}$. These findings highlight the significant chemical tunability of the PdRSb family, positioning them as promising candidates for future applications in spintronics and magnetoelectronics. Full article

A novel mesoporous XAD-based adsorbent (A336/XAD-7) was produced by impregnating the ionic liquid A336 into the pores of XAD-7 resin and used to separate tin(IV) and cadmium(II) from high-level liquid waste (HLLW). The as-produced material was characterized by SEM-EDS, TG-DSC, and N₂ adsorption–desorption isotherms, which revealed a well-developed open pore structure, high loading capacity, and large specific surface area. Adsorption performance analysis showed that in 4 M HCl solution, the experimental saturated adsorption capacity qexp of A336/XAD-7 for Sn(IV) and Cd(II) were 39.51 mg/g and 34.18 mg/g, respectively, with equilibrium reached within 120 min. Among ten coexisting metal ions (Sn⁴⁺, Cd²⁺, Co²⁺, Ni²⁺, Cu²⁺, Eu³⁺, Y³⁺, Ca²⁺, Mg²⁺, Al³⁺) in HLLW, A336/XAD-7 exhibited excellent selectivity for Sn(IV) under high acidity, with a separation factor (SF_Sn/others) of 13.13. Column experiments further evaluated the dynamic separation of Sn(IV) from simulated HLLW using A336/XAD-7, achieving an enrichment factor greater than 7. XPS spectra indicated that the adsorption mechanism involved anion exchange between A336/XAD-7 and the complex anions SnCl₆²⁻ and CdCl₄²⁻. This work demonstrates the application potential of A336/XAD-7 for HLLW treatment and provides valuable guidance for the efficient separation of other metal ions. Full article

Electrocatalytic nitric oxide reduction (NORR) shows great potential for mitigating NO_x emissions from motor vehicles and other internal combustion engine exhausts, enabling the resource utilization of pollutant NO and the synthesis of NH₃ under mild conditions. The overall performance of NORR largely depends on the development of efficient electrocatalysts. Based on a coordination-engineering strategy, this study constructs a series of Sc-based single-atom catalyst systems coordinated with nonmetal heteroatoms (X = B, C, O, Si, P, S, As, Se, Te), denoted as Sc@XN₃, and systematically investigates their NORR reaction pathways, limiting potentials (U_L, the minimum applied potential required to make all elementary steps downhill in free energy), and selectivity using density functional theory (DFT) calculations. The results indicate that Sc@CN₃, Sc@PN₃, and Sc@SN₃ possess relatively low U_L, with values of −0.17, −0.31, and −0.07 V, respectively, among which Sc@SN₃ is thermodynamically the most favorable. Moreover, Sc@CN₃ and Sc@SN₃ can suppress the hydrogen evolution reaction (HER) and the formation of N₂O/N₂ by-products, thereby affording higher selectivity toward NH₃ formation. Considering the characteristics of NO_x emissions from engine exhaust, these coordination-engineered Sc centers show promising potential for future electrified aftertreatment systems that couple NO_x control with ammonia-based energy utilization in vehicles. This study clarifies at the atomic scale how the coordination environment modulates the electronic structure and catalytic behavior of Sc single-atom centers and provides theoretical guidance for the rational design of high-performance NORR electrocatalysts targeted at automotive exhaust NO_x control. Full article

Rare earth has been widely introduced in heat-resistant steel. However, excessive amounts of rare earth should be added due to the low yield rate, and the molten steel in the mold was highly reducible. Severe slag–metal interface reactions occurred when conventional mold fluxes were used. To restrain interfacial reactions during continuous casting of heat-resistant steel containing rare earth, a new method for designing mold flux was proposed, and different flux systems containing rare earth oxide were devised. The properties such as melting temperature, viscosity, and crystalline phase of the different mold fluxes were systematically investigated. Comparisons of properties between the new fluxes and the conventional mold fluxes were conducted. The results show that properties similar to those of the conventional mold flux could be obtained by adopting Li₂O and B₂O₃ as fluxing agents in the newly designed system. The new mold flux with high content of CaO and Al₂O₃ had approximate properties with the conventional mold flux. Cerium oxide could not separate out in the continuous cooling process. The main crystalline phase was LiAlO₂ in the new mold fluxes, which is different from the cuspidine (3CaO∙2SiO₂∙CaF₂) in the conventional mold flux. LiAlO₂ can be a potential substitute for cuspidine. It was entirely feasible to devise and develop a new mold flux containing rare earth with a high content of CaO and Al₂O₃ for rare earth steel continuous casting by further optimizing its properties. Full article

The particular microstructure of hot-deformed Nd-Fe-B magnets leads to difficulties in finding a direct recycling route. In this work, a combination of field-assisted sintering technology/spark plasma sintering (FAST/SPS) and spark plasma texturing (SPT) is used as pre-compaction and deformation techniques, respectively, for the consolidation of crushed, hot-deformed Nd-Fe-B scrap. Field-assisted sintering has the unique advantage of maintaining fine microstructures during material densification, making it an ideal candidate for direct recycling of this material. Recycled magnets, made from 100 wt% crushed magnet scrap, were able to achieve energy products of over 200 kJ m⁻³ after FAST/SPS pre-compaction and SPT deformation. These recycled magnets could then be smoothed and cut to the size of industrial bar magnets for testing in the motor of a water pump. When tested, the recycled magnets could achieve 95% of the electromotive force compared to industrial standard magnets. Full article

Light-converting polymer coatings and films are emerging passive photonic materials for spectral engineering in sustainable and protected agriculture. By absorbing ultraviolet or weakly used spectral components and re-emitting in visible bands that overlap with photosynthetic pigments and plant photoreceptor action regions, these materials can modify the radiation environment without additional electrical energy input. This critical narrative review analyses light-converting polymer films and coatings from a materials and coatings perspective, with emphasis on photophysical mechanisms, polymer matrices, luminophore families, coating fabrication routes, optical transparency, photoluminescence, aggregation phenomena, photostability and scalability. The photobiological background is included as a concise framework that justifies the spectral targets of the conversion process. Rare-earth complexes, inorganic phosphors, quantum dots, aggregation-induced-emission systems and organic dyes are compared as candidate luminophores. Particular attention is devoted to the general challenges associated with organic luminescent coatings, including dispersion, aggregation, optical transparency, photostability, and scalability. A PMMA/PDI coating system is discussed only as an illustrative case study demonstrating these broader materials-design considerations. Extrusion, solution casting, spin-coating, dip-coating and sol–gel processing are evaluated as fabrication strategies for laboratory and large-area greenhouse applications. The work concludes by identifying the main gaps that must be addressed before practical deployment: quantitative UV–Vis and photoluminescence characterization, absolute quantum yield, haze and scattering, thickness and morphology mapping, accelerated UV aging, weathering resistance, toxicity assessment and crop-specific validation. Full article