Search Results (2,136)

This work develops a novel phosphate-functionalized extraction resin (HEHEHP + Cyanex272)/SiO₂-P via the vacuum impregnation method for efficient separation of light rare earth element impurities from lanthanum (La³⁺) in nitric medium through synergistic extraction. Batch experiments have demonstrated superior adsorption selectivity toward impurity ions over La³⁺ in a pH 4 nitric acid solution. Column studies confirmed exceptional performance under ambient conditions, achieving a lanthanum treatment capacity of 120.6 mg/g and over 98% impurity removal, which surpasses most reported values. Notably, this purification process enables direct production of purified La³⁺ solutions through a single-column system without desorption, significantly enhancing efficiency and reducing costs. Mechanistic insights revealed combined ion exchange and coordination interactions between metal ions and P-OH/P=O groups, corroborated by advanced characterization and density functional theory calculations. These findings indicate a higher binding affinity of light rare earth compared with La³⁺. This strategy provides a scalable approach for ultra-high-purity lanthanum compound production in advanced optical and electronic applications. Full article

The integration of petrological and geochemical analyses serves as an effective methodology for reconstructing depositional environments and constraining sediment provenance within distinct tectonic frameworks. This study investigates the provenance characteristics of the Silurian Kepingtag Formation in the northwestern Tarim Basin through an integrated approach combining field outcrop observations and laboratory analyses. Fieldwork covers the Sishichang, Dawangou, and Tongguzibulong sections, while laboratory analyses include clastic component identification, whole-rock major and trace element geochemical analysis, and rare earth element (REE) profiling. These efforts enable a systematic evaluation of sediment sources and their tectonic linkages. The research provides a theoretical basis for understanding the tectono-sedimentary framework of the northwestern Tarim Basin during the Early Silurian and offers significant guidance for reconstructing the lithofacies paleogeographic pattern of the basin during this period. Petrographic analyses reveal a lithological assemblage dominated by lithic quartz sandstones and lithic sandstones, with subordinate feldspathic lithic sandstones. Quartz exhibits secondary overgrowths. In a relatively stable tectonic environment, sediments undergo a gentle burial rate, which favors the formation of this phenomenon. Lithic fragments are dominated by magmatic lithics, indicating that the source contains magmatic rocks. Detrital component analysis reveals that the provenance of Kepingtag Formation sandstones in the study area is predominantly characterized by stable craton and recycled orogenic belt tectonic settings. Integrated geochemical datasets from major element compositions and trace element signatures constrain the provenance characteristics of the Kepingtag Formation sandstones. Major element ratios demonstrate predominant contributions from felsic igneous source rocks, while trace element ratios are diagnostic of sediment derivation from passive continental margin settings, consistent with prolonged tectonic quiescence along the northern Tarim cratonic margin during Silurian deposition The CIA index indicates that the Silurian Kepingtag Formation in the study area exhibits weak to moderate weathering. Integrating the above analyses, the Tabei Uplift—ancient craton setting—is interpreted as the likely provenance source for the sandstones of the Kepingtag Formation in the northwestern Tarim Basin. Full article

Weathered crust elution-deposited rare earth ores (WCE-REOs) are the primary global source of medium and heavy rare earth elements (M/HREEs). The recent discovery of high-altitude (1500–2500 m) WCE-REOs in southern Yunnan Province, China, presents new opportunities for the development of M/HREE resources. This study investigates the enrichment and fractionation mechanisms of rare earth elements (REEs) in these deposits through a systematic analysis of three representative weathering profiles associated with the Lincang granite batholith. The analytical results indicate that the profiles consist mainly of clay minerals (kaolinite, halloysite, illite, minor montmorillonite) and iron oxides, with high SiO₂ (64.10–74.40 wt.%) and Al₂O₃ (15.50–20.20 wt.%) and low CaO/MgO—typical of weathered REE deposits. The total REE contents (238.12–1545.53 ppm) show distinct fractionation: LREE-enriched upper layers and HREE-enriched deeper zones. Sequential extraction revealed that the REEs in the Lincang granite weathering profiles predominantly occur in ion-exchangeable, residual, and iron-manganese oxide-bound states (>95% total REEs). Ion-exchangeable REEs showed depth-dependent enrichment (peaking at 819.96 ppm), while iron-manganese oxides exhibited a strong REE affinity (up to 47% total REEs), with amorphous phases that were preferentially enriched in Ce (partitioning >80%). Fissure systems exerted critical control over the redistribution of elements, particularly REEs. Full article

This study investigates the influence of RE elements on the room- and high-temperature properties of magnesium alloys. The effects of RE type, addition level, and multi-element alloying strategies were systematically analyzed to clarify the underlying strengthening mechanisms and processing pathways for optimizing Mg–RE alloys. RE elements enhance the mechanical and thermal properties of Mg alloys through crystal structure modification, formation of thermally stable dispersed phases, precipitation strengthening, and solid-solution strengthening. Compared with conventional alloying elements, RE additions offer distinct advantages in strengthening efficiency and overall performance. To fully exploit these benefits, new research paradigms that integrate machine learning and other advanced techniques are required, enabling the intelligent design of multicomponent alloy systems tailored to specific application requirements. Full article

RMB₆-TMB₂ (RM = rare earth elements, TM = transition metal elements) composites retain superior field emission properties of RMB₆ while addressing its inherent mechanical limitations by constructing a eutectic structure with TMB₂. Herein, an in situ route for synthesizing RMB₆-TMB₂ composite nanopowders with homogeneous phase distribution using reduction reactions was proposed. The LaB₆-ZrB₂ composite nanopowders were synthesized in situ for the first time using sodium borohydride (NaBH₄) as both a reducing agent and boron source, with lanthanum oxide (La₂O₃) and zirconium dioxide (ZrO₂) serving as metal sources. The effects of the synthesis temperature on phase compositions and microstructure of the composites were systematically investigated. The LaB₆-ZrB₂ system with a eutectic weight ratio exhibited an accelerated reaction rate, achieving a complete reaction at 1000 °C, 300 °C lower than that of single-phase ZrB₂ synthesis. The composite phases were uniformly distributed even at nanoscale. The composite powder displayed an average particle size of ~170 nm when synthesized at 1300 °C. With the benefit of the in situ synthesis method, LaB₆-TiB₂, CeB₆-ZrB₂, and CeB₆-TiB₂ composite powders were successfully synthesized. This process effectively addresses phase separation and contamination issues typically associated with traditional mixing methods, providing a scalable precursor for high-performance RMB₆-TMB₂ composites. Full article

Single crystals of the layered EuRECuTe₃ series with RE = Nd, Sm, Tb and Dy are obtained for the first time, completing the series of studies on quaternary tellurides synthesized using the halide flux method. These compounds crystallize in the orthorhombic space group Pnma (no. 62) with unit cell parameters ranging from a = 11.5634(7) Å, b = 4.3792(3) Å and c = 14.3781(9) Å for EuNdCuTe₃ to a = 11.2695(7) Å, b = 4.3178(3) Å and c = 14.3304(9) Å for EuDyCuTe₃. The influence of prismatic polyhedra [EuTe₆₊₁]⁷⁻ structural units on the stabilization of 3d framework composed by 2d layered fragments [RECuTe₃]²⁻, which have a key role in the interlayer interaction, is established. A comparative analysis of structural and magnetic properties dependence on the rare-earth element radius r_i(RE³⁺) in the EuRECuTe₃ series (RE = Sc, Y, Nd–Lu) is carried out. The structural contraction, including decrease in degree of tetrahedral polyhedra distortion, bond lengths shortening and unit cell volume shrinking with increasing r_i(RE³⁺), is established. It is shown that the structural alternation leads to transition from ferromagnetic to ferrimagnetic ordering. It was established that changes in the cationic sublattice have a more significant impact on structural transitions in the series of quaternary tellurides than changes in the anionic sublattice. The electronic structure and elastic and dynamic properties were estimated using ab initio calculations. The exfoliation energy for each compound is obtained by estimation of monolayer ground state energy as a result of structure relaxation. The symmetry and structural properties of monolayer EuRECuTe₃ (RE = Nd, Sm, Tb, Dy) compound are established and the orthorhombic symmetry is obtained with layer group pm2_1b. Full article

The widespread use of rare earth elements (REEs) in agriculture, particularly Lanthanum (La), raises concerns about their ecological impact on non-target organisms. We investigated the direct and indirect effects of La on the insect pest Spodoptera littoralis and its host plant, Brassica rapa. Direct exposure to La-supplemented diets reduced larval growth, survival, and egg production. Interestingly, a transgenerational effect was observed, where larvae from La-exposed parents exhibited increased resilience, showing no performance reduction on the same diets. Indirectly, La accumulation in plants mediated a hormetic response in herbivores, increasing larval weight at low concentrations but reducing it at high concentrations, while modulating their oxidative stress and detoxification gene expression. From the plant perspective, La exposure amplified herbivory-induced calcium signalling and altered the expression of key genes related to calcium and reactive oxygen species pathways. These findings reveal the complex ecological risks of La accumulation in agroecosystems, affecting both plants and insects directly and through novel transgenerational effects. Full article

A para-substituted 1,10-phenanthroline ligand, 2-(4-methylphenoxy)-1,10-phenanthroline (L24), was synthesized and structurally characterized. Complexes with Eu³⁺, Tb³⁺, Sm³⁺, and Dy³⁺ were obtained in a 2:1 ligand-to-metal ratio and analyzed using single-crystal x-ray diffraction, photoluminescence spectroscopy, and TD-DFT calculations. Coordination via the phenanthroline nitrogen atoms, combined with steric asymmetry from the para-methylphenoxy group, induces low-symmetry environments favorable for electric-dipole transitions. Excited-state lifetimes reached 2.12 ms (Eu³⁺) and 1.12 ms (Tb³⁺), with quantum yields of 42% and 68%, respectively. The triplet-state energy of L24 (22,741 cm⁻¹) aligns well with emissive levels of Eu³⁺ and Tb³⁺, consistent with Latva’s criterion. Fluorescence titrations indicated positively cooperative complexation, with association constants ranging from 0.60 to 1.67. Stark splitting and high ⁵D₀ → ⁷F₂/⁷F₁ intensity ratios (R₂ = 6.25) confirm the asymmetric coordination field. The para-methylphenoxy substituent appears sufficient to lower coordination symmetry and strengthen electric-dipole transitions, offering a controlled route to enhance photoluminescence in Eu³⁺ and Tb³⁺ complexes. Full article

Identifying stratigraphic continuity across outcrops can sometimes be difficult, especially if they are dominated by discontinuous strata. Therefore, stratigraphers continue to seek new proxies for testing stratigraphic continuity, including fossiliferous horizons. We present a case study examining the potential of fossil bone trace element signatures as a novel proxy for lateral continuity. Specifically, we performed trace element analyses of Edmontosaurus bones from the Neufeld Quarry at Hanson Ranch (HR) in Wyoming, a stratigraphically verified lateral equivalent of the famous HR Bonebed exposed nearby in five “Main Quarries”, to evaluate if these chemical data would independently lead a researcher to the same conclusion of lateral equivalency. Bones from the “Main Quarries” and Neufeld were found to exhibit similar patterns of trace element alteration, including comparable magnitudes of enrichment, spatial patterns of rare earth element uptake, and proportions of specimens exhibiting various styles of diagenetic alteration. Many bones from both sites also exhibit redox signatures indicative of trace element uptake under reducing conditions. These numerous similarities in geochemical alteration patterns independently indicate that the fossil horizon at Neufeld is a lateral continuation of the nearby HR Bonebed. Our findings thus demonstrate the power of trace elements toward identifying laterally equivalent fossil assemblages. Full article

Dromedary camels raised under semi-extensive management can act as One Health sentinels for environmental exposures and food chain surveillance, yet serum reference information remains scarce. Our objective was to provide the most comprehensive assessment to date of physiological and toxicological serum profiles in dromedary camels (Camelus dromedarius) from the Canary Islands. We included 114 clinically healthy animals of different sex, age, and reproductive status. Serum samples were analyzed for essential, toxic, and potentially toxic elements using inductively coupled plasma mass spectrometry (ICP-MS). In addition, a high-throughput multi-residue method based on QuEChERS extraction followed by UHPLC-MS/MS and GC-MS/MS was used to screen for 360 organic compounds, including pesticides, veterinary drugs, human pharmaceuticals, and persistent organic pollutants. Essential elements showed biologically consistent variations according to sex, age group, and pregnancy status. Males had higher levels of selenium and copper, while calves showed elevated concentrations of manganese and zinc. Pregnant females exhibited lower iron, zinc, and selenium levels, consistent with increased fetal demand. These results provide preliminary reference values for healthy camels, stratified by physiological status. In contrast, classical toxic elements such as arsenic, mercury, lead, and cadmium were found at very low or undetectable concentrations. Several potentially toxic elements, including barium, strontium, and rare earth elements, were detected sporadically but without toxicological concern. Only 13 organic compounds (3.6%) were detected in any sample, and concentrations were consistently low. The most prevalent was the PAH acenaphthene (55.3%), followed by the fungicide procymidone and the PAH fluorene. Notably, no residues of the usually detected 4,4′-DDE or PCB congeners were found in any sample. These findings confirm the low environmental and dietary exposure of camels under low-intensity farming systems and highlight their value as sentinel species for food safety and environmental monitoring. Full article

The Chaluo granite is situated in the middle section of the Yidun magmatic arc in western Sichuan Province, China. It holds great significance for the study of the geological evolution of the Paleo-Neotethys tectonic belts. The Chaluo granite mainly consists of alkaline feldspar, quartz, and biotite, with a small amount of apatite. LA-ICP-MS zircon U-Pb dating yielded crystallization ages of (87 ± 3) Ma for the Chaluo granite, indicating its formation in the Late Cretaceous. Elemental geochemical testing results showed that the Chaluo granite exhibits I-type granite characteristics. It has undergone significant fractional crystallization processes, with high SiO₂ contents (72.83–76.63 wt%), K (K₂O/Na₂O = 1.33–1.53), Al₂O₃ (Al₂O₃ = 12.24–13.56 wt%, A/CNK = 0.91–1.08), and a high differentiation index (DI = 88.91–92.49). Notably, the MgO contents were low (0.10–0.26 wt%), and there were significant depletions of Nb, Sr, Ti, and Eu, while Rb, Pb, Th, U, Zr, and Hf were significantly enriched. The total rare earth element (REE) contents were relatively low (211–383 ppm), showing significant light REE (LREE) enrichment (LREE/HREE = 4.46–5.57) and a pronounced negative Eu anomaly (δEu = 0.09–0.17). In situ zircon Hf analyses, combined with ²⁰⁶Pb/²³⁸U ages, gave ε_Hf(t) values ranging from −3.8 to 1.72 and two-stage Hf ages (t_DM2) of 875–1160 Ma. Together with the S and Pb isotope compositions of the Chaluo granite, its magma likely originated from the partial melting of Middle–Neoproterozoic sedimentary rocks enriched in biogenic S. The tectonic-setting analysis indicates that the Chaluo granite formed in a post-orogenic intracontinental extensional environment. This environment was triggered by the northward subduction-collision of the Lhasa block, followed by slab break-off and the upwelling of the asthenosphere in the Neo-Tethys orogenic belt. We propose that the Paleo-Tethys tectonic belt was influenced by the Neo-Tethys tectonic activity, at least in the Yidun magmatic arc region during the Late Cretaceous. Full article

Major powers compete over the 17 rare earth elements (REEs), which are strategic resources in traditional, green, and high-tech areas. The escalation of international trade conflicts poses a serious threat to the sustainable growth of the rare earth industry, triggering an investigation of the global trade landscape for diverse rare earth products. Taking cerium, the most abundant and widely traded REE, as an example, this study selected seven representative cerium products, constructed their global trade networks from 2000 to 2022, depicted macro, meso, and micro trade patterns, and revealed the impact of four major events on China’s trade influence. The findings demonstrate that (1) the trade volume of cerium products in green and high-tech sectors has increased significantly, surpassing that of cerium products in traditional sectors and upstream primary products, and (2) the global cerium trade networks are interconnected, regionalized, stable, and efficient. Germany, the U.S., and other European nations have long dominated mid- and downstream cerium product commerce, but China’s involvement has grown. (3) China’s cerium trade influence has significantly increased, positively shocked by major events. The research findings provide solid empirical support and policy insights for promoting the sustainable and high-quality development of the global cerium industry chain. Full article

Despite extensive research on sediment provenance in the Bohai Sea (BS), a significant knowledge gap persists concerning long-term provenance evolution, particularly in the western BS since the Middle Pleistocene. This shortcoming limits reconstructions of paleoenvironmental evolution and its interplay with climatic variability and sea-level fluctuations. This study presents integrated Rare Earth Element (REE) geochemical and sedimentological analyses of sediments from core DZQ01 in the western BS. The mean ΣREE concentration of 178.78 μg/g is characterized by pronounced light REE (LREE) enrichment relative to heavy REE (HREE). Chondrite- and upper continental crust (UCC)-normalized patterns exhibit distinct negative Eu anomalies, variable Ce anomalies, marked LREE enrichment, and pronounced LREE/HREE fractionation. Grain size exerts the dominant control on REE distribution, whereas the weak correlation between HREE fractionation parameter indices (e.g., Gd/Yb) and redox-sensitive proxies (e.g., δEu_UCC and δCe_UCC) confirms their fidelity as provenance indicators. When integrated with the δEu_UCC-δCe_UCC diagram, discriminant functions, and paleoenvironmental proxies (Rb/Sr and Mg/Ca ratios), the data indicate that, during interglacial highstands, the Yellow River (YR) was the principal source, delivering fine-grained terrigenous material from the Loess Plateau and thereby elevating REE concentrations. Conversely, glacial lowstands shifted the depositional environment to subaerial conditions, with the YR, Hai River, and Luan River supplying a coarse-fine admixture. Multi-river provenance and dilution by coarse detritus collectively lowered REE concentrations during these intervals. Full article

It is generally believed that the ancient oceans during the “boring billion” (1.85–0.8 Ga) lacked the capacity to form large-scale iron formations (IFs), though localized small-scale IFs deposition persisted. The Altyn region of China hosts abundant IFs, with the Dimunalike IFs being the largest and most representative, characterized by typical banded iron–silica layers. Detailed fieldwork identified a tuff layer conformably contacting the IFs at the roof rocks of IFs and a ferruginous mudstone layer at the floor rocks of IFs in drill core ZK4312. Geochemical and zircon U-Pb-Hf isotopic analyses were performed. The tuff has a typical tuff structure, mostly made of quartz, and contains a significant amount of natural sulfur. It also has high SiO₂ content (77.90%–80.49%) and sulfur content (0.78%–3.06%). The ferruginous mudstone has a volcanic clastic structure and is mainly composed of quartz and chlorite, with abundant coeval pyrite. It shows lower SiO₂ content (53.83%–60.32%) and higher TFe₂O₃ content (10.29%–16.24%). Both layers share similar rare earth element (REE) distribution patterns and trace element compositions, with light REE enrichment and negative Eu, Nb, and Ti anomalies, consistent with arc volcanic geochemistry. Zircon U-Pb ages indicate crystallization of the tuff at 1102 ± 13 Ma and maximum deposition of the mudstone at 1110 ± 41 Ma. These data suggest formation during different stages of the same volcanic–sedimentary process. The ε_Hf(t) values (3.60–12.35 for tuff, 2.92–8.19 for mudstone) resemble those of Algoma-type IF host rocks, implying derivation from re-melted new crust. The Dimunalike IFs likely formed in a submarine volcanic–sedimentary environment. In conclusion, although the Mesoproterozoic ocean was generally in a low-oxygen state, which was not conducive to large-scale IF deposition, localized submarine volcanic–hydrothermal activity could still lead to IF formation. Full article

To address the critical challenges in pyrometallurgical recycling processes—such as poor feedstock adaptability, high energy consumption during roasting conversion, and the low added value of rare earth products—this study systematically investigated the mechanism and process optimization of ammonium bifluoride (NH₄HF₂) roasting for the recovery of neodymium–iron–boron (NdFeB) waste. Thermodynamic analysis confirmed the feasibility of the conversion reaction between NH₄HF₂ and the rare earth components in NdFeB waste. Single-factor experiments were conducted to examine the effects of roasting temperature, reaction time, and NH₄HF₂ dosage on rare earth recovery. The optimal conditions were a roasting temperature of 600 °C, a reaction time of 120 min, and a NH₄HF₂ dosage of 75 wt%, achieving a rare earth recovery rate of 98.81%. Furthermore, the response surface methodology (RSM) was employed to establish a quantitative model correlating process parameters with recovery efficiency. Variance analysis demonstrated that the model was highly significant (F = 136.94, p < 0.0001), with excellent agreement between actual and predicted values (R² = 0.9944). Factor contribution analysis revealed that NH₄HF₂ dosage had the most pronounced impact on rare earth fluorination, followed by roasting temperature and reaction time. Under optimized conditions, the purified rare earth fluoride obtained after acid leaching reached a purity of 99.43%, providing high-quality raw material for producing high-value-added rare earth products. Full article