Rare Earth Research Articles

Validation of McCARD Monte Carlo Calculation Code Against NAA Experiments Using Rare Earth Element Certified Reference Material Activated at JRTR

Rare earth elements (REEs) are widely used in several high-tech modern industries. Quantification of REEs demonstrates a technical challenge that requires the use of special scientific techniques. These techniques commonly introduce uncertainties that may propagate not only during the sample preparation phase but also in subsequent measurement and analysis phases. The Jordan Atomic Energy Commission is starting up a REE investigation program utilizing many of its available physical and chemical analytical capabilities, one of which is the Neutron Activation Analysis Facility (NAAF) at the Jordan Research and Training Reactor (JRTR). The NAAF provides accurate and relatively quick analytical services for better estimations of REEs in the unknown samples of interest without the need for any chemical processing prior to or after sample activation. In this paper, we present analytical results of routinely conducted instrumental neutron activation analysis (NAA) experiments using REE certified samples. To optimize future NAA investigations, first, a time-dependent Monte Carlo code at the JRTR, named Monte Carlo Code for Advanced Reactor Design and Analysis (McCARD), is herein validated via comparing its calculation results of the activation process against the presented results of the NAA experiments. The certified REE samples were activated in a well-thermalized NAA vertical activation hole within the reactor reflector region. Detailed neutronics and burnup calculations as well as transmutations were performed using McCARD. Ultimately, this study aims to assess the accuracy and reliability of the McCARD calculation models as a part of the effort of setting up a dedicated REE analysis laboratory at the JRTR. This study shows very good agreement between both obtained results—NAA experiment and McCARD calculations—with confidence levels noted to be more than 90% for almost all REE elements.

Effects of interlayer spacing and applied pressure on the lanthanide transport in MoS2-based two-dimensional channels

ABSTRACT Rare-earth elements (REEs) are critical to modern industry but difficult to separate due to their subtle and monotonic changes in physicochemical properties. MoS2-based two-dimensional (2D) materials offer novel opportunities for enhancing REE separation, exhibiting a distinct volcano-shaped transport performance distribution that peaks at Sm3+. However, the specific contributions of thermodynamic and kinetic factors to ion transport within 2D confinement remain unclear. In this study, we conducted a series of non-equilibrium all-atom molecular dynamics (MD) simulations to explore the effects of interlayer spacing and external pressure on the transport of lanthanide ions in Å-scale acetate functionalized 2D MoS2 (MoS2-COOH) channels. We examined ion entry and permeation rates, water flux, dehydration, and binding modes. The simulation results reveal that the transport trends of lanthanide ions are jointly driven by the dehydration degree and the relative-binding strengths of ions to water and to the acetate within the 2D channels. Notably, the dehydration pattern of lanthanide ions during permeation is closely linked to kinetic factors. Overall, this study provides a detailed atomistic understanding of the mechanisms underlying lanthanide ion transport under confinement. These findings point to the significant potential for tuning confinement and chemical functionalization within Å-scale channels for more efficient REE separation.

Class II (three-layer system) phenomenological model based on limiting current density and dynamic chelation chemistry for separation of rare earth elements using electrodialysis

This paper presents an in-depth investigation into the optimization of rare earth element (REE) separation through electrodialysis, leveraging a newly developed Class II phenomenological model. This study explores the pivotal roles of the HEDTA/Nd molar ratio and pH of feed solution on enhancing the separation efficiency of neodymium (Nd) and praseodymium (Pr) from lanthanum (La) and cerium (Ce). By integrating expanded Nernst-Planck equations and the concept of limiting current density, the model offers a sophisticated understanding of ion transport dynamics and the impacts of concentration polarization. Experimental validation confirms the model’s predictive accuracy, demonstrating its practical applicability for industrial-scale operations. The research delineates how operational parameters such as chelating agent concentration and pH critically influence the purity and yield of separated REEs. The dynamic nature of chelation chemistry is also examined, highlighting its evolution during the electrodialysis process and its effect on the system’s overall performance. Key findings illustrate that lower HEDTA/Nd molar ratios significantly enhance the purity of Nd + Pr by minimizing the chelation of La and Ce, thus facilitating their migration to the concentrate compartment. Conversely, higher ratios maximize yield by retaining more Nd + Pr in the feed compartment. This dual approach allows for optimized separation based on specific industrial requirements. The outcomes of this study not only advance the field of REE separation but also provide a framework for further research into more efficient and sustainable extraction methods. The developed model and its validation represent a step forward in the practical application of electrodialysis in REE processing, offering substantial benefits for the critical materials sector.

Ligand-selective turn-off sensing, harvesting and post-adsorptive use of Dy(III) and Yb(III) by intrinsically fluorescent flower-shaped Gum Acacia-grafted hydrogels

Rare earth metals (REMs), such as Dysprosium (Dy) and Ytterbium (Yb), have experienced unprecedented demand in recent times due to their applications in high-end technologies. REMs are found only in select geographic locations placing tremendous economic constraints on their use. In this work, we have developed Gum Acacia-grafted hydrogels (GmAc-FluoroTerPs) that are capable of selective detection and capture of Dy and Yb. The intrinsically blue fluorescent polymer hydrogel GmAc-FluoroTerP has been optimized for Dy(III) and Yb(III) specific quenching, enabling limit of detection of the REMs at 0.13 nM and 60.8 pM, respectively. A comprehensive structural characterization of the fluorescent hydrogel has been performed via NMR, FTIR, XPS, EPR, TGA, XRD, TEM, SEM, EDX, TCSPC, and DLS. In addition to an in situ generated fluorophore, GmAc-FluoroTerP displays a distinctive aggregation induced emission enhancement in mixed solvents. The complexation of Dy(III)/Yb(III) with GmAc-FluoroTerP hydrogel has been characterized by XPS, TCSPC, and logic gate analyses, and the adsorptive capacity for Dy(III) and Yb(III) are found to be best reported till date as 125.57 mg g−1 and 102.27 mg g−1, respectively. Desorption at acidic pH allows recovery of the REMs. We also report semiconducting behaviour of the native fluorescent hydrogel, that is enhanced upon adsorptive capture of Dy(III) and Yb(III), with calculated band gaps at 1.37, 0.77, and 0.49 eV, respectively. The convergent sensing, capture, and reuse of Dy(III) and Yb(III) presented in this work promises a hitherto unreported template for application on other REMs.

Eu3+-functionalized covalent organic framework for ratiometric fluorescence detection and adsorption of tetracycline and information steganography.

Functional materials with organic/inorganic composites as the main matrix and rare earth ion complexes as the guest have shown a very broad application prospect for antibiotic sensors. However, Eu3+-complex often relies on a single fluorescence response signal, which is susceptible to changes in the detection environment and cannot simultaneously detect and remove tetracycline (TC). Herein, green fluorescent covalent two-dimensionalorganic framework (COF-TD) is synthesized, followed by modification of Eu3+ to synthesize COF-TD@Eu3+. In the ratiometric sensor, Eu3+ serves as the recognition site and specific response probe for TC, while COF-TD is the fluorescence reference and carrier for Eu3+. Due to the antenna effect, TC enhances the red fluorescence of Eu3+, while the green fluorescence of COF-TD remainsalmost stable. Based on the change of fluorescence intensity and fluorescence color from green to red, the efficient ratiometric sensing can be finished in 1min. The developed method shows high sensitivitywith a detection limit of 0.3μM and highselectivity to TC which makes the methodapplicableto detect TC in traditional Chinese medicine preparations. In addition, due to the high specific surface area of COFs and specific adsorption sites, COF-TD@Eu3+ also shows good performance for TC removal. The findings show that the maximum adsorption capacity is 137.3mgg-1 and the adsorption equilibrium is reached in 30min. Smartphone assisted COF-TD@Eu3+ for both ratiometric fluorescence detection and detecting the absorption ofTC is proposed for the first time. The molecular cryptosteganography that transforms the selective response of COF-TD@Eu3+ to binary strings is anticipated to advance utilization of nanomaterials in logic sensing and information safety.

Lower Gondwana palaeobotany and geochemistry of phosphorite occurrence in the north‐western part of Ib‐River Coalfield, Odisha, India, and their implications

The present investigation breaks new ground by examining the Raniganj sediments in the Kendudihi section of the Ib‐River Coalfield, Odisha, India. The study identifies a megaflora consisting of 25 species of Glossopteris, Vertebraria indica, stem casts and equisetaceous stems. The microflora is predominantly composed of Striatopodocarpites spp., with a secondary presence of Densipollenites spp. The lithological signatures, including off‐white fine‐grained sandstone with thin bands of silty shale and grey shale, indicate that these sediments belong to the Late Permian succession of the Lower Gondwana sequence, specifically the Raniganj Formation. The macrofloral assemblage found in the lowermost grey shale can be attributed to the Wordian–Capitanian age, while the microfloral assemblage in the upper silty shale resembles that of the Wuchiapingian‐Changhsingian age. Well‐preserved palynomorphs and megafossils, along with the abundant occurrence of lath‐shaped translucent phytoclasts in the grey and silty shale of the Raniganj sediments exposed in the Kendudihi section, explicitly suggest that the sediments were deposited in proximal, low‐energy swampy settings. Additionally, the moderate occurrence of charcoal (20%), along with the existence of degraded organic matter (DOM: 7.6%) and amorphous organic matter (AOM: 16.4%), indicates that the sediments might have been deposited in oxic–dysoxic conditions. The palynological and megafloral studies reveal a warm‐temperate climate with low humidity and intermittent spells of hot and cold seasons, associated with abundant rainfall. The occurrence of phosphorite in the form of nodules and thin lenses, as well as biogenic structures at the juncture of the Raniganj and Barren Measures formations, suggests a marine incursion in the area during the deposition of the late Barren Measures and early Raniganj sediments. X‐ray diffraction (XRD) analysis identified fluorapatite (Ca5(PO4)3F) as the predominant phosphatic mineral phase in the phosphatic nodule, siltstone and claystone. The Post‐Archean Australian Shale composition, normalized rare earth element (REE) patterns of samples from this area, reveals slight positive La (average La anomaly: 1.02) and Gd (average Gd anomaly: 1.05) anomalies and heavy REE enrichment compared to light REE, explicitly indicating a marine environment.

Petrographic and geochemical analysis of lunar meteorite NWA 11788: Parallels with Luna 20 and the Apollo magnesian granulites

AbstractThe first in‐depth geochemical and petrological analyses of new lunar meteorite Northwest Africa (NWA) 11788 were conducted with the aim of better understanding the diversity of lunar rock types. Petrography, microcomputed tomography, electron probe microanalysis, and laser ablation inductively coupled plasma mass spectrometry were employed to analyze mineralogic/elemental makeup, petrologic profile, melt history, and inferred composition of the lunar mantle from which the crystals in this sample originated from. Geochemical maps of the lunar surface were generated to constrain potential lunar launch locations for NWA 11788. Potential launch locations are concentrated in the outer rims of impact basins on the lunar Eastern nearside limb (e.g., Crisium, Fecunditatis, Marginis, Smythii) and around the South Pole–Aitken Basin. Similarities in the major, minor, and trace element chemistry of NWA 11788 along with its potential launch locations suggest a petrogenetic relationship with regolith samples returned from the Luna 20 mission and the Apollo 16 and 17 magnesian granulites. Additionally, the results of this study add to the growing body of evidence that KREEP (potassium, rare earth elements, phosphorous)‐poor, Mg‐suite‐“like” lithologies are common in non‐Apollo‐type locales, that KREEP may not be required to generate lithologies like the Mg‐suite, and that KREEP is not globally distributed at present.

From nickel–metal hydride batteries to advanced engines: A comprehensive review of hydrogen's role in the future energy landscape

Hydrogen has emerged as a disruptive force in the energy landscape, poised to revolutionise the automotive sector with its use in both fuel cell and internal combustion engines. This article covered two topics: application of metal hydrides for hydrogen storage and use of cutting-edge engine technology in hydrogen-powered vehicles. This article begins with discussing the different characteristics of materials that are used to store hydrogen. Metal hydrides, rare earth elements, and carbon-based compounds are among the materials that are carefully studied in this work. Understanding how effectively these materials can store hydrogen was another goal of this research. In order to fully utilize hydrogen's potential, it is imperative to compare them with conventional fossil fuels highlighting their significance. Additionally, this study explains how hydrogen can be used to power existing and newer automobile vehicles. Also discussed are the viability and potential mechanisms of operation for various hydrogen-using engine technologies, such as compression ignition and spark ignition engines. Cutting-edge on vehicles with fuel cell and engine technology powered by hydrogen along with their challenges are explained. They include discussions of several techniques such as homogenous charge compression ignition (HCCI), dual-fuel, and reactivity-controlled combustion ignition (RCCI). Additionally, the advantages and disadvantages of utilizing hydrogen in these state-of-the-art engine technologies are discussed. This research offers insights on the future of automobiles in addition to hydrogen storage. This study points the path towards a more creative and sustainable energy environment in which hydrogen plays a major role in the storage and utilization for automobile vehicles.

Determination of the banded iron formation sources in the Lanling area of Western Shandong of the North China Craton through rare earth element testing

Determination of the banded iron formation sources in the Lanling area of Western Shandong of the North China Craton through rare earth element testing

Enhancement of Electromagnetic Wave Attenuation through Polarization Loss Induced by Hybridization of Rare‐Earth 4f and Mo‐4d Orbitals in Liquid Plasma

AbstractThe incorporation of large‐sized rare earth (RE) elements with high coordination characteristics into transition metal dichalcogenide (TMD) absorbers while preserving a high 1T phase content during post‐processing poses a significant challenge. To address this, a novel strategy involving the confinement of RE elements within the 1T‐MoS2 lattice via liquid plasma assistance, is proposed. This approach effectively mitigates the environmental impact on the 1T phase of MoS2, yielding a remarkable 1T phase content of 82.69% for Ce20‐D7 (20 wt.% Cerium trinitrate and 7 kV applied voltage). Combining experimental and theoretical investigations reveals that the multi‐orbital characteristics of RE elements facilitate hybridization between the RE‐4f and Mo‐4d orbitals on the MoS2 surface, leading to the occupation of weakly bound electrons in bonding orbitals with short‐distance motion, enhanced inter‐orbital electron‐electron interactions, and induced polarization loss. Notably, the results demonstrate that the Pr15‐D7 sample (15 wt.% praseodymium nitrate and 7 kV applied voltage) exhibits an effective absorption bandwidth (EAB) of 7.12 GHz at 2.6 mm, with a minimum reflection loss of ‐52.02 dB while the Ce20‐D7 sample achieves an EAB of 6.96 GHz at 2.7 mm. These findings provide valuable insights for the rational design and development of high‐performance TMD absorbers leveraging RE‐modified materials.

Virus-Based Separation of Rare Earth Elements.

The utilization of biomaterials for the separation of rare earth elements (REEs) has attracted considerable interest due to their inherent advantages, including diverse molecular structures for selective binding and the use of eco-friendly materials for sustainable systems. We present a pioneering methodology for developing a safe virus to selectively bind REEs and facilitate their release through pH modulation. We engineered the major coat protein of M13 bacteriophage (phage) to incorporate a lanthanide-binding peptide. The engineered lanthanide-binding phage (LBPh), presenting ∼3300 copies of the peptide, serves as an effective biological template for REE separation. Our findings demonstrate the LBPh's preferential binding for heavy REEs over light REEs. Moreover, the LBPh exhibits remarkable robustness with excellent recyclability and stability across multiple cycles of separations. This study underscores the potential of genetically integrating virus templates with selective binding motifs for REE separation, offering a promising avenue for environmentally friendly and energy-efficient separation processes.

Carbonatites and related mineralization: an overview

Despite of their scarcity, carbonatites are documented from diverse geological settings, including cratons, continental rifts, orogenic belts, and large igneous provinces, ranging in age from Archean to Recent. This study provides a concise overview of the evolution of igneous carbonatites, compiling data on their diverse characteristics and classifying them into mantle-derived and crustal-derived sub-types. Mantle-derived carbonatites, typically associated with alkaline rocks, are enriched in rare earth elements (REE) and display geochemical affinities to the mantle. By contrast, crustal-derived carbonatites usually show much lower REE contents and crustal-affinity geochemical features similar to sedimentary carbonaceous rocks. Our study documents the significant economic potential of carbonatites which can host world-class deposits of REE, rare metals, alkaline earth metals, and non-metallic resources. Typically, the key processes controlling the REE mineralization include the low-degree melting of refertilised mantle, liquid immiscibility, fractional crystallization, and hydrothermal fluids. Thus, carbonatites are of significant economic value due to the rapidly increasing global demand for REE, mainly driven by the ‘green energy transition’.

Rare earth elements sequestration in phytoliths: Partitioning patterns and influencing mechanism

Rare earth elements (REEs) are integral to numerous high-tech industries, yet their biogeochemical cycling within ecosystems remains inadequately characterized. Recently, phytoliths have been identified as potentially significant sinks for REEs; however, their role in the cycling of these elements has been underestimated. In this work, we investigate the accumulation of REEs in phytoliths (PhytREEs) within the Greater Khingan Mountains region, employing an optimized wet oxidation method combined with heavy liquid flotation to quantify PhytREEs contents in surface soils. The results revealed an elevation-dependent pattern of PhytREEs concentration, with heightened levels at higher altitudes and diminishing concentrations towards the eastern plains. The enrichment coefficient of PhytREEs (ECPhytREEs) was found to be approximately 2.7 %, indicative of a moderately selective sequestration process. The multivariate analysis indicated that terrain complexity, climatic patterns, soil texture, and organic matter significantly influence the uptake and storage of REEs in plants, subsequently affecting their partitioning in phytoliths. Among these factors, the complexation of REEs with organic matter emerged as a pivotal mechanism facilitating their immobilization within phytoliths. Soil characteristics also play a non-negligible role in modulating REEs dynamics. Our findings highlight the predominant influence of climate on PhytREE storage, suggesting that climatic variables are the primary drivers modulating the bioavailability and ultimate sequestration of REEs within phytoliths. This study enhances our understanding of the biotic-abiotic interplay in the sequestration of REEs and underscores the need to incorporate phytoliths into models of terrestrial REE cycling.

Metal–Organic Framework-Derived Rare Earth Metal (Ce-N-C)-Based Catalyst for Oxygen Reduction Reactions in Dual-Chamber Microbial Fuel Cells

Pt supported on carbon (Pt/C) is deemed as the state-of-the-art catalyst towards oxygen reduction reactions (ORRs) in chemical and biological fuel cells. However, due to the high cost and scarcity of Pt, researchers have focused on the development of Earth-abundant non-precious metal catalysts, hoping to replace the traditional Pt/C catalyst and successfully commercialize the chemical and biological fuel cells. In this regard, electrocatalysts made of transition metals emerged as excellent candidates for ORRs, especially the electrocatalysts made of Fe and Co in combination with N-doped carbons, which produce potentially active M-N4-C (M=Co, Fe) ORR sites. At present, however, the transition metal-based catalysts are popular; recently, electrocatalysts made of rare earth metals are emerging as efficient catalysts, due to the fact that rare earth metals also have the potential to form rare earth metal-N4-C active sites, just like transition metal Fe-N4-C/Co-N4-C. In addition, mixed valance states and uniqueness of f-orbitals of the rare earth metals are believed to improve the redox properties of the catalyst that helps in enhancing ORR activity. Among the rare earth metals, Ce is the most interesting element that can be explored as an ORR electrocatalyst in combination with the N-doped carbon. Unique f-orbitals of Ce can induce distinctive electronic behavior to the catalyst that helps to form stable coordination structures with N-doped carbons, in addition to its excellent ability to scavenge the OH● produced during ORRs, therefore helping in catalyst stability. In this study, we have synthesized Ce/N-C catalysts by a metal–organic framework and pyrolysis strategy. The ORR activity of Ce/N-C catalysts has been optimized by systematically increasing the Ce content and performing RDE studies in 0.1 M HClO4 electrolyte. The Ce/N-C catalyst has been characterized systematically by both physicochemical and electrochemical characterizations. The optimized Ce/N-C-3 catalyst exhibited a half-wave potential of 0.68 V vs. RHE. In addition, the Ce/N-C-3 catalyst also delivered acceptable stability with a loss of 70 mV in its half-wave potential when compared to 110 mV loss for Pt/C (10 wt.%) catalyst, after 5000 potential cycles. When Ce/N-C-3 is used as a cathode catalyst in dual-chamber microbial fuel cells, it delivered a volumetric power density of ⁓ 300 mW m−3, along with an organic matter degradation of 74% after continuous operation of DCMFCs for 30 days.

Characterization of rare-earth-doped photocells based on p-GaSe/n-InSe heterojunctions

The effect of doping with holmium (Ho) and erbium (Er) rare-earth elements (REE) on the main parameters and characteristics of photocells based on p-GaSe/n-InSe heterostructures has been experimentally studied. Photo-electromotive force measurements were performed for undoped and rare-earth doped samples and obtained results comparatively analyzed. The light characteristic of the samples shows that significant improvement are observed in the rare-earth doped crystals. The possibility of targeted control, as well as increasing their reproducibility and stability by changing the content of the introduced impurity ([Formula: see text]), is shown. The optimal situation is provided by alloying Er with [Formula: see text] at.%.

Noise pollution assessment and management in rare earth mining areas: a case study of Kollam, Kerala, India.

Noise pollution is an unintentional consequence of mining activities, needing rigorous assessment, monitoring, and mitigation techniques to reduce its impact on local residents and ecosystems. The study specifically examines the noise pollution from rare earth mining activities in the Neendakara-Kayamkulam (NK) coastal belt, Kollam, Kerala, India, a region rich in ilmenite, rutile, sillimanite, zircon, and monazite. Despite the known environmental and health impacts of noise pollution, there is limited specific data on its magnitude and sources in this region, as well as a lack of effective mitigation strategies tailored to rare earth mining operations. Studies have indicated that mining operations, such as the movement of heavy mineral sands, considerably elevate noise levels, which have an effect on the environment's quality and public health. This study seeks to fill the gap by geospatial mapping and assessing the noise levels and recommend measures to effectively mitigate noise pollution. Systematic noise measurements were conducted at 48 suitable locations within the NK coastal belt, including residential, commercial, industrial, coastal, and silence zones. The noise levels vary from 49.1dB(A) near a religious place to 82.4dB(A) near the local industry. The study employs geospatial noise mapping and land cover superimposition to implement class-specific mitigation measures for noise pollution in a coastal vicinity mixed land use area, including natural and vegetative barriers, operational scheduling, zoning, and land use planning.

Trace element geochemistry of carbonatites and associated alkaline rocks of Mundwara Igneous complex, Sirohi district, Rajasthan, India

Carbonatites are widely recognized for their potential to host significant deposits of rare earth elements (REEs) and other rare metals. These igneous rocks, characterized by their high carbonate mineral content, are often rich in REEs, niobium, tantalum, and other valuable elements. This makes carbonatites key targets for mining and exploration. Carbonatites are believed to form from either primary carbonate magma derived directly from the mantle or from secondary melts. These secondary melts can originate from carbonated silicate magmas through liquid immiscibility or from the residual melts resulting from the fractional crystallization of silicate magmas. The coexistence of carbonatites and alkaline silicate rocks in most complexes, their coeval emplacement in many, and overlapping initial 87Sr/86Sr ratios supports the theory of their cogenesis. In this study, we aim to investigate the trace element geochemistry of carbonatites and coeval alkaline silicate rocks from the Mundwara Igneous Complex, Sirohi district, Rajasthan in India. Our trace element data indicate that the carbonatites and alkaline silicate rocks in this complex are products of fractional crystallization from two separate parental melts, formed through liquid immiscibility of a carbonated alkaline silicate magma.

Systematic First-Principles Investigations of the Nucleation, Growth, and Surface Properties of Al11RE3 Second-Phase Particles in Al-Based Alloys

At room temperature, Al alloys have excellent mechanical properties and are widely used in automotive, electronics, aerospace and other fields, but it is difficult to maintain this advantage in the middle and high temperature ranges. To address this issue, second-phase Al11RE3 (RE represents rare earth element) was introduced into a Al-Mg-RE alloy as its primary constituent. By incorporating RE elements as additives, this material exhibits exceptional mechanical and thermal properties at elevated temperatures. Based on first principles and quasi-harmonic approximation (QHA), the nucleation growth mechanism and surface properties of second-phase Al11RE3 were studied in this paper. The interfacial energy γα/β, strain energy ΔECS and chemical driving force ΔGV of Al11RE3 were obtained. Models1, 4, and 6 have better properties of para-site connections than inter-site connections. It is found that the resistances of particle nucleation, interface energy γα/β and strain energy ΔECS, first increase and then decrease with increased atomic number REs, but they are much smaller than the chemical driving force ΔGV. A reduced chemical driving force and a diminished nucleation radius R* are more favorable for the process of nucleation. The addition of Sc is the most unfavorable for nucleation, and La has the strongest nucleating ability, which gradually decreases as the atomic number of the lanthanide element increases. The nucleation ability of the Al11RE3 phase decreases with increasing temperature, which is consistent with the experiments. The nucleation radius R* also increases with increasing temperature, indicating that the nucleation ability decreases as the atomic number of the lanthanide elements increases. Since the smaller the nucleation radius R* the easier the nucleation, compared with model4 and 6, model1 has a smaller nucleation radius R* and the smallest increment. Thus, model1 is more prominent in the nucleation mechanism. In the particle growth study, the smaller the diffusion activation energy Q, the faster the diffusion rate in the Al matrix, and hence the higher the coiling rate, which promotes the growth of second-phase particles. The diffusion activation energy Q decreases sequentially from La to Ce and then increases with atomic number. The coarsening rate KLSW of the Al11RE3 phase in models1, 4, and 6 increased with increasing temperature, which promoted the growth of particles. This paper is intended to provide a solid theoretical basis for the production and application of aluminum alloy at high temperatures.

Mass balance and economic study of a treatment chain for nickel, cobalt and rare earth elements recovery from Ni-MH batteries

ABSTRACT The aim of this project is to develop and evaluate the economic performance of a complete process for recovering nickel, cobalt, and rare earths (REEs) from nickel metal hydride (Ni-MH) battery waste. The main elements contained in the battery powder are Ni (523 g/kg), La (58 g/kg), Co (39 g/kg), Zn (21 g/kg), Nd (19 g/kg), Sm (19 g/kg) and Ce (14 g/kg). Metal leaching was carried out with 2 M sulfuric acid, solubilising 100% of Ni, 93% of Co and 94% of REEs. Rare earths were precipitated with NaOH, then purified after resolubilization in nitric acid. Solvent extraction with bis(2-ethylhexyl) phosphoric acid (D2EHPA) followed by bis(2,4,4-trimethylpentyl) phosphinic acid (Cyanex 272) was used to separate Ni and Co. At the end of the process, REEs, nickel, and cobalt were recovered as oxides after precipitation as oxalates. The REE, nickel and cobalt oxides obtained have purities of 97.6%, 97.2% and 93.2% respectively. A techno-economic study was carried out using SuperPro Designer software. In this scenario, plant capacity was set at 1.0 t of used battery powder per hour for an operating period of 8 h/d and 250 days per year. The total investment was estimated at $26.9 million, with a payback period of 1.58 years. For a 15-year life, the net present value of this project is estimated at $95.9 million, with an interest rate of 7%. The internal rate of return is estimated at 46.1%, which is considered acceptable and economically viable.

Synthesis and characterization of cubic δ–phase stabilized Bi2O3 electrolytes by triple rare earth cation doping for intermediate temperatures SOFCs

Face–centered cubic–Bi2O3 (δ–phase), a high–ion conductor, is an essential solid electrolyte option, particularly for low–low–temperature SOFC applications. It is widely accepted that δ–Bi2O3 exhibits higher conductivity than the YSZ electrolytes typically utilized in HT–SOFC units. The present study investigates the structural, thermal, surface, and conductivity characteristics of the Bi2O3 electrolytes co–doped with Tb–Sm–Gd rare earth. The XRD data indicate that, except composition 20Tb20Sm20Gd, all compositions are stabilized with the cubic δ–phase at room temperature. The estimated lattice constants additionally suggest lattice contraction, confirming that the partial cation substitutes between host Bi3+ and rare earth cations are successful. The DTA curves do not have any endothermic or exothermic peaks, indicating a possible phase transition. Arrhenius plots prove that DC conductivity decreases as the dopant ratio increases, implying a drop in polarization power. The highest conductivity is found to be 0.131 S/cm for the composition 10Tb10Sm10Gd.