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We present an efficient first-principles based method geared toward reliably predicting the structures of solid materials across the Periodic Table. To this end, we use a density functional theory baseline with a compact, near-minimal min+s basis set, yielding low computational costs and memory demands. Since the use of such a small basis set leads to systematic errors in chemical bond lengths, we develop a linear pairwise correction, available for elements Z = 1–86 (excluding the lanthanide series), parameterized for use with the Perdew–Burke–Ernzerhof exchange–correlation functional. We demonstrate the reliability of this corrected approach for equilibrium volumes across the Periodic Table and the transferability to differently coordinated environments and multi-elemental crystals. We examine relative energies, forces, and stresses in geometry optimizations and molecular dynamics simulations. [ABSTRACT FROM AUTHOR]

Alloying with rare earth (RE) elements is an effective way to improve the mechanical properties of the Mg alloys. However, the strengthening mechanism of RE element Y on the Mg alloys still needs to be further revealed. The effect of grain boundary (GB) segregation of RE element Y on the mechanical properties and the GB stability of the Mg alloys are investigated by the molecular dynamics simulation method. The results show that the GB segregation of Y atoms can significantly increase the yield strength and GB stability of the Mg alloys. The higher the content of Y atoms at the GB, the stronger the stability of the GB and the higher the strength of the alloys. The results also show that the GBs thicken significantly with increasing Y content at the GBs, which is attributed to the diffusion of Y atoms, leading to the solid-state amorphization of the Mg alloys. The results indicate that with the increase of Y content at the GBs, the Mg alloys undergo a transition from the plastic deformation dominated by the co-sliding of GBs and dislocations to the slip of dislocations only. This work provides a theoretical basis for the design and preparation of high-performance Mg alloys. [ABSTRACT FROM AUTHOR]

The article presents the study of the magnetocaloric effect (MCE) for the rhombohedral Laves phase of Pr 2 Rh 3 Ge, which shows a magnetic order below T C = 8.5 K. We have established that the compound exhibits a continuous second-order type of transition which was demonstrated and confirmed by several different techniques, mainly by analyzing universal curves of normalized entropy change as a function of scaled temperature. The observed MCE, in our opinion, is a consequence of an indirect exchange coupling between the magnetic sublattices of the rare earth ions, which, however, does not exclude the potential contribution of sublattice-containing transition metals. In this paper, the procedure to evaluate the MCE from magnetization and specific heat data is described. As a result, important parameters such as the isothermal magnetic entropy change (Δ S M), adiabatic temperature change (Δ T a d ), relative cooling power (RCP), and the temperature averaged entropy change (TEC) were determined. The highest values of − Δ S M , Δ T a d , and RCP for a field change (Δ μ 0 H) of 5 T at T C are 5.96 J/kg K, 3.87 K, and 72.62 J/kg, respectively. These results obtained for Pr 2 Rh 3 Ge seem to be, however, low compared to the values obtained for the rhombohedral Laves phases, belonging to the group of ternary germanides RE 2 Rh 3 Ge containing heavy rare earth metals (RE = Gd, Tb, Ho, and Er). Nevertheless, we believe that the results presented in this work extend and complement the current knowledge on the magnetocaloric properties of this family of materials. [ABSTRACT FROM AUTHOR]

We construct correlation-consistent effective core potentials (ccECPs) for a selected set of heavy atoms and f elements that are currently of significant interest in materials and chemical applications, including Y, Zr, Nb, Rh, Ta, Re, Pt, Gd, and Tb. As is customary, ccECPs consist of spin–orbit (SO) averaged relativistic effective potential (AREP) and effective SO terms. For the AREP part, our constructions are carried out within a relativistic coupled-cluster framework while also taking into account objective function one-particle characteristics for improved convergence in optimizations. The transferability is adjusted using binding curves of hydride and oxide molecules. We address the difficulties encountered with f elements, such as the presence of large cores and multiple near-degeneracies of excited levels. For these elements, we construct ccECPs with core–valence partitioning that includes 4f subshell in the valence space. The developed ccECPs achieve an excellent balance between accuracy, size of the valence space, and transferability and are also suitable to be used in plane wave codes with reasonable energy cutoffs. [ABSTRACT FROM AUTHOR]

The evolution of the valence band, charge states of atoms, and optical and vibrational spectra in compounds Ca10−xMx(PO4)xY2, M = Fe, Ni, Cu, Mg; Y = OH, Cl, F was studied by using XPS, infrared, and optical spectroscopy, with the addition of quantum mechanics calculations. The changes in the bandgap in these compounds were analyzed. Isomorphic substitution of calcium ions in the cationic sublattice of calcium hydroxyapatite by metal ions changes the shape of the curve that represents the occupied part of the valence band only slightly. It retains a pronounced gapped character with different lengths of individual subbands—the upper and lower parts of the valence band. It is shown that the predominant position of rare earth and uranium atoms in the apatite structure is the Ca(2)-position. Isomorphic substitution of calcium atoms by metal atoms (Fe, Ni, Cu, Mg) in the apatite structure in the range of 1%–2% of atoms leads to the narrowing of the energy gap. The most significant narrowing is observed when calcium is substituted by nickel and copper. The theoretically calculated bandgap width in calcium apatites can be well described in terms of the generalized gradient approximation. The design of the structure of calcium apatites via the method of isomorphic substitutions in the cation sublattice makes it possible to control the bandgap width, thus expanding the field of practical application of these compounds. [ABSTRACT FROM AUTHOR]

This month's column is Part 2 of a contribution from my daughter Glenna, who recently completed her PhD studies in Environmental Science from the University of Copenhagen in Denmark. Her article explores the current landscape of global critical raw materials (CRM) trends in research and the applications of atomic spectroscopy (AS), including inductively coupled plasma-mass spectrometry (ICP-MS), inductively coupled plasma-optical emission spectrometry (ICP-OES), and X-ray analytical techniques in their identification of diverse industrial and environmental media, which have been essential in method validation and quantification of CRMs in complex matrices presenting high risks of interference. Some important examples to be presented include rare earth elements (REEs) in water leaching purification (WLP) residues that co-occur with radioactive materials; REEs and other metals in acid mine drainage (AMD) environments; REEs in coal combustion (fly ash) residues; arsenic (As) from groundwater treatment sediment; and platinum-group elements (PGEs) from sewage sludge. The article also classifies the different techniques in use at each stage of the CRM recovery train, investigates present challenges to each analytical method, and discusses the problem-solving tools used., - Rob Thomas, Column Editor Part 1 of this article focused on the overview of critical raw materials (CRMs), the global context for sustainable sourcing of CRMs, and the recent […]

Although it plays a critical role in the photophysics and catalysis of lanthanides, spin–orbit coupling of electrons on individual lanthanide atoms in small clusters is not well understood. The major objective of this work is to probe such coupling of the praseodymium (Pr) 4f and 6s electrons in Pr2O2 and Pr2O2+. The approach combines mass-analyzed threshold ionization spectroscopy and spin–orbit multiconfiguration second-order quasi-degenerate perturbation theory. The energies of six ionization transitions are precisely measured; the adiabatic ionization energy of the neutral cluster is 38 045 (5) cm−1. Most of the electronic states involved in these transitions are identified as spin–orbit coupled states consisting of two or more electron spins. The electron configurations of these states are 4f46s2 for the neutral cluster and 4f46s for the singly charged cation, both in planar rhombus-type structures. The spin–orbit splitting due to the coupling of the electrons on the separate Pr atoms is on the order of hundreds of wavenumbers. [ABSTRACT FROM AUTHOR]

Paramagnetic molecules with a metal ion as an electron spin center are promising building blocks for molecular qubits and high-density memory arrays. However, fast spin relaxation and decoherence in these molecules lead to a rapid loss of magnetization and quantum information. Nonadiabatic coupling (NAC), closely related to spin-vibrational coupling, is the main source of spin relaxation and decoherence in paramagnetic molecules at higher temperatures. Predicting these couplings using numerical differentiation requires a large number of computationally intensive ab initio or crystal field electronic structure calculations. To reduce computational cost and improve accuracy, we derive and implement analytical NAC and state-specific energy gradient for the ab initio parametrized crystal field Hamiltonian describing single-ion molecular magnets. Our implementation requires only a single crystal field calculation. In addition, the accurate NACs and state-specific energy gradients can be used to model spin relaxation using sophisticated nonadiabatic molecular dynamics, which avoids the harmonic approximation for molecular vibrations. To test our implementation, we calculate the NAC values for three lanthanide complexes. The predicted values support the relaxation mechanisms reported in previous studies. [ABSTRACT FROM AUTHOR]

The rare earth alloy Y 2 Co 17 − x Ni x was prepared by a low-cost co-precipitation reduction-diffusion process, and its crystal structure, static magnetic properties, and microscopic morphology were systematically characterized. The effects of Ni doping with different contents on the electromagnetic parameters and wave absorption properties of Y 2 Co 17 − x Ni x /polyurethane(PU) compounds were researched in the frequency range of 0.1–18 GHz. The results show that the static magnetic properties and wave absorption properties change significantly with Ni doping, and the maximum reflection loss of Y 2 Co 14 Ni 3 /PU reaches − 89.7 dB at 2.9 mm thickness, and the maximum reflection loss peaks of Y 2 Co 17 /PU and Y 2 Co 16 Ni 1 /PU are at 1.316 and 1.515 GHz, which is at the center frequency of the L-band. With Ni doping, the effective absorption bandwidth of the compounds at a frequency above 3 GHz is greatly increased. The physical factor in the bandwidth calculation was modified, and the effective absorption bandwidth of the material was calculated theoretically, and the error was less than 5 % compared with the experimental value. [ABSTRACT FROM AUTHOR]

Magnetocaloric properties of TbCrO3 and TmCrO3 are reported and compared with those of the previously reported rare-earth chromites RCrO3 (R = Gd, Dy, Ho, and Er) and other perovskite-type oxides. The samples of TbCrO3 and TmCrO3 in this work were synthesized using a citrate gel combustion technique, and their magnetic properties were investigated and compared with those reported previously on RCrO3 (R = Gd, Dy, Ho, and Er). The Cr3+–Cr3+ ordering temperatures were found to strongly depend on the ionic radii of the rare-earth. By fitting the dc magnetization data with modified Curie–Weiss law including the Dzyaloshinsky–Moriya antisymmetric exchange interaction (D) and the symmetric exchange constant Je, spin canting angles (α) were obtained. In general, α was found to increase with the decreasing ionic radii of R3+ in RCrO3. The magnetocaloric properties investigated included the magnetic entropy change (−ΔS) for a given change in magnetic field (ΔH), the corresponding adiabatic temperature change (ΔTad), and their relative variations (ΔTad/ΔH) and (−ΔS/ΔH). It is observed that for RCrO3, (−ΔS) measured in the vicinity of the ordering temperature of R3+–R3+, varies almost as G2/3 where G is the de Gennes factor. Among RCrO3, GdCrO3 shows the largest value of (−ΔS/ΔH), because of its largest G factor and its magnitudes of (ΔTad/ΔH) and (−ΔS/ΔH) compare well with the reported values for the perovskites GdFeO3 and EuTiO3. These comparisons presented here provide useful information on the potential use of these materials in magneto-refrigeration technology. [ABSTRACT FROM AUTHOR]

Recent experiments performed on chiral molecules, comprising transition metal or rare earth elements, indicate temperature reinforced chiral induced spin selectivity. In these compounds, spin selectivity is suppressed in the low temperature regime but grows by one to several orders of magnitude as the temperature is increased to room temperature. By relating temperature to nuclear motion, it is proposed that nuclear displacements acting on the local spin moments, through indirect exchange interactions, generate an anisotropic magnetic environment that is enhanced with temperature. The induced local anisotropy field serves as the origin of a strongly increased spin selectivity at elevated temperature. [ABSTRACT FROM AUTHOR]

Compositional tuning of magnetic properties to provide technologically useful results is in the forefront of research in complex oxides. Taking advantage of the highly sensitive nature of magnetism in 6H barium ruthenates (Ba3MRu2O9, M = transition metals or rare earth ions) to composition, we have carried out M-site dual doping by 50% each of Co and Mn. The high pressure and high temperature synthesized sample of 6H Ba3Co0.5Mn0.5Ru2O9 shows giant exchange bias (5.71 kOe at 5 K and 50 kOe cooling field) and huge coercivity (9.42 kOe at 5 K) at low temperature along with Griffiths phase like behavior in the 136 K < T < 260 K temperature range. The presence of ferromagnetic (FM) clusters in a non-collinear antiferromagnetic (AFM) background for temperature below 136 K is assumed. These FM clusters extend above 136 K to persist until 260 K, and the system finally reaches the paramagnetic (PM) state closer to room temperature. The exchange bias phenomena diminish above 20 K and this could be correlated with the peculiar nature of magnetic isotherms above and below this temperature. The transition at 136 K is regarded as AFM short-range ordering from ac and dc magnetization studies and heat capacity measurement. The presence of short-range interactions at temperatures until the PM region forms the basis of Griffiths phase like behavior in this sample. [ABSTRACT FROM AUTHOR]

A-site high entropy Ba4(La0.2Nd0.2Sm0.2Eu0.2Y0.2)2Ti4Nb6O30 tungsten bronze ceramics were designed and prepared by a standard solid state sintering process. First-order ferroelectric transition occurs around 240 °C on heating, while around 136 °C on cooling. Pinched and asymmetric P–E hysteresis loops were observed within and below the thermal hysteresis temperature range of the ferroelectric transition. Pinched P–E hysteresis loops were attributed to the coupling between the ferroelectric transition and the commensurate/incommensurate modulation transition. The reason for the asymmetry of the hysteresis loop was the presence of an internal bias electric field. Different measuring procedures were designed to clarify the evolution of hysteresis loop asymmetry. The existence of oxygen vacancy and Eu3+/Eu2+ was identified by x-ray photoemission spectroscopy. The electric field cycling with elevated temperatures caused defect dipoles incline to align along the direction of spontaneous polarization leading to the internal bias electric field. Due to the A-site high entropy effect, dielectric strength of Ba4(La0.2Nd0.2Sm0.2Eu0.2Y0.2)2Ti4Nb6O30 ceramics is up to 300 kV/cm, which is increased by more than 50% than that with the single element in the A1-site. [ABSTRACT FROM AUTHOR]

Indium-111 (111In) is a diagnostic radiometal that is important in nuclear medicine for single-photon emission computed tomography (SPECT). In order to apply this radiometal, it needs to be stably chelated and conjugated to a targeting vector that delivers it to diseased tissue. Identifying effective chelators that are capable of binding and retaining [111In]In3+ in vivo is an important research area. In this study, two 18-membered macrocyclic chelators, py-macrodipa and py2-macrodipa, were investigated for their ability to form stable coordination complexes with In3+ and to be effectively radiolabeled with [111In]In3+. The In3+ complexes of these two chelators were characterized by NMR spectroscopy, X-ray crystallography, and density functional theory calculations. These studies show that both py-macrodipa and py2-macrodipa form 8-coordinate In3+ complexes and attain an asymmetric conformation, consistent with prior studies on this ligand class with small rare earth metal ions. Spectrophotometric titrations were carried out to determine the thermodynamic stability constants (log KML) of [In(py-macrodipa)]+ and [In(py2- macrodipa)]+, which were found to be 18.96(6) and 19.53(5), respectively, where the values in parentheses are the errors of the last significant figures obtained from the standard deviation from three independent replicates. Radiolabeling studies showed that py-macrodipa and py2-macrodipa can quantitatively be radiolabeled with [111In]In3+ at 25 °C within 5 min, even at ligand concentrations as low as 1 μM. The in vitro stability of the radiolabeled complexes was investigated in human serum at 37 °C, revealing that ∼90% of [111In][In(py-macrodipa)]+ and [111In][In(py2-macrodipa)]+ remained intact after 7 days. The biodistribution of these radiolabeled complexes in mice was investigated, showing lower uptake in the kidneys, liver, and blood at the 24 h mark compared to [111In]InCl3. These results demonstrate the potential of py-macrodipa and py2-macrodipa as chelators for [111In]In3+, suggesting their value for SPECT radiopharmaceuticals. [ABSTRACT FROM AUTHOR]

Energy dissipation through physical downscaling towards more complex types of memory and logic devices, loss of ultrapure water and consumption of large amounts of (toxic) chemicals for wafer cleaning processes, as well as high thermal budget of solid-state synthesis and thin film growth of standard semiconductors including the use of rare earth elements – all this poses great challenges for semiconductor materials science and technology. Therefore, research and development of alternative methods for micro- and nanofabrication and chemical functionalization of a new type of resource- and energy-efficient semiconductors as the core component of every computer chip is crucial. One of the promising opportunities is the transformation of today’s complementary metal-oxide-semiconductor (CMOS) electronics into ecofriendly and neuroinspired electronics driven by molecular design and multi-level switching mechanisms at room temperature. The sustainable chemical technology of electron transport and switching materials in semiconductor manufacturing and the development of devices with new unconventional nanophysics, improved performance, and augmented functionalities (beyond-CMOS and More-than-Moore) is becoming increasingly important in the context of a gradual transition to a future-oriented concept of Internet of Everything (IoE). In this article, we focus on the technological significance of semiconductor preparation from single-source (molecular) precursors and the prospect of functionalizing semiconductors using DNA origami nanotechnology and stimuli-responsive metal–oxygen cluster ions such as polyoxometalates (POMs). We also describe the advanced characterization of these qualified molecular systems by soft X-rays. We emphasize the technical relevance of using solution-based methods for the bottom-up preparation of novel and hybrid semiconductors as well as their challenging scalability and the compatibility of methods of molecular technology with lithography-based mass production. Our article aims to contribute to the achievement of the United Nations’ Sustainable Development Goal 9 (Industry, Innovation and Infrastructure). [ABSTRACT FROM AUTHOR]

Rare earth elements possessing a diverse range of optical, electrical, and magnetic properties has attracted more attention. In the present work, GdClWO 4 compound with monoclinic structure was prepared, the structure, magnetism and magnetocaloric effect (MCE) were investigated. The magnetic phase transition temperature (T N), magnetic ground state and maximum magnetic entropy change ( − Δ S M max) were derived from magnetization measurements. Both first principles calculation and experimental results suggest that the compound displays antiferromagnetic (AFM) interactions, with a magnetic transition occurring at 0.6 K, shifting from a paramagnetic (PM) state to an AFM state. The − Δ S M max is up to 35.2 J kg−1 K−1 (205.9 mJ cm−3 K−1) for GdClWO 4 at T = 1.3 K under a magnetic field change of 0–50 kOe. In particular, the volumetric magnetic entropy change still remains 83.1 mJ cm−3 K−1 at 0.5 K and μ 0 Δ H = 20 kOe, which is almost twice as much as that of commercial refrigerant Gd 3 Ga 5 O 12 (GGG) under μ 0 Δ H = 20 kOe, establishing GdClWO 4 compound as a potential candidate for cryogenic refrigeration applications. [ABSTRACT FROM AUTHOR]

Novel heteroleptic anilate-based lanthanide MOFs (LnIII = Tb, Dy, Ho) have been obtained under hydrothermal conditions by the ancillary ligand synthetic strategy. These structurally isomorphous species contain octacoordinated LnIII ions with coordination polyhedra approaching an ideal D2d symmetry, best described by a distorted biaugmented trigonal prismatic C2v geometry. In the whole series, only the Dy-MOF exhibits SMM behaviour. [ABSTRACT FROM AUTHOR]

The impact of substituents at the 4- and 7-positions of 1,10-phenanthroline-2,9-dicarboxamides on the photophysical properties of the ligands and their coordination compounds with the lanthanide triad--europium, gadolinium, and terbium--was analyzed. This study demonstrates how modification of the electronic nature of ligands through the incorporation of diverse functional groups affects the luminescence properties of their complexes. The introduction of various substituents leads to the appearance of intra-ligand or ligand-to-ligand charge transfer (CT) states. The highest luminescence efficiency was observed for LH·Eu(NO3)3 (Qin = 54.1% and QL = 9.6%), suggesting strong luminescence quenching of the CT state. It was found that a relatively low ΔE (-3000 cm-1) supports direct energy transfer from S1 to T1 bypassing the CT state, even though it is outside Reinhoudt's optimal range. The introduction of fluorines leads to the strongest luminescence quenching among all the substituents. [ABSTRACT FROM AUTHOR]

In this work, bovine serum albumin (BSA) and Aspergillus sp. laccase (LC) were encapsulated in situ within two lanthanide-based MOFs (TbBTC and GdBTC) through a green one-pot synthesis (almost neutral aqueous solution, T = 25 °C, and atmospheric pressure) in about 1 h. Pristine MOFs and protein-encapsulated MOFs were characterized through wide angle X-ray scattering, scanning electron microscopy, thermogravimetric analysis, Fourier transform infrared and Raman spectroscopies. The location of immobilized BSA molecules, used as a model protein, was investigated through small angle X-ray scattering. BSA occurs both on the inner and on the outer surface of the MOFs. LC@TbBTC, and LC@GdBTC samples were also characterized in terms of specific activity, kinetic parameters, and storage stability both in water and acetate buffer. The specific activity of LC@TbBTC was almost twice that of LC@GdBTC (10.8 μmol min-1 mg-1vs. 6.6 μmol min-1 mg-1). Both biocatalysts showed similar storage stabilities retaining -60% of their initial activity after 7 days and -20% after 21 days. LC@TbBTC dispersed in acetate buffer exhibited a higher storage stability than LC@GdBTC. Additionally, terbium-based MOFs showed interesting luminescent properties. Together, these findings suggest that TbBTC and GdBTC are promising supports for the in situ immobilization of proteins and enzymes. [ABSTRACT FROM AUTHOR]

Background: Rare-earth sulfide nanoparticles (NPs) could harness the optical and magnetic features of rare-earth ions for applications in nanotechnology. However, reports of their synthesis are scarce and typically require high temperatures and long synthesis times. Results: Here we present a biosynthesis of terbium sulfide (TbS) NPs using microorganisms, identifying conditions that allow Escherichia coli to extracellularly produce TbS NPs in aqueous media at 37 °C by controlling cellular sulfur metabolism to produce a high concentration of sulfide ions. Electron microscopy revealed ultrasmall spherical NPs with a mean diameter of 4.1 ± 1.3 nm. Electron diffraction indicated a high degree of crystallinity, while elemental mapping confirmed colocalization of terbium and sulfur. The NPs exhibit characteristic absorbance and luminescence of terbium, with downshifting quantum yield (QY) reaching 28.3% and an emission lifetime of ~ 2 ms. Conclusions: This high QY and long emission lifetime is unusual in a neat rare-earth compound; it is typically associated with rare-earth ions doped into another crystalline lattice to avoid non-radiative cross relaxation. This suggests a reduced role of nonradiative processes in these terbium-based NPs. This is, to our knowledge, the first report revealing the advantage of biosynthesis over chemical synthesis for Rare Earth Element (REE) based NPs, opening routes to new REE-based nanocrystals. [ABSTRACT FROM AUTHOR]

Here, we report petrography, whole-rock geochemistry, and zircon U-Pb geochronology to understand the origin, source, geodynamic setting, and evolution of A-type granite and granite gneiss as well as establish their emplacement age from Mahakoshal Basin. Mineralogically, Sidhi granite gneiss and Madanmahal granite of the Mahakoshal Basin dominantly consist of quartz, K-feldspar, and plagioclase. Geochemically, Sidhi granite gneiss and Madanmahal granite are ferroan in nature. The studied rocks are akin to peraluminous A-type granites and have average zircon saturation temperatures of 955°C and 977°C, respectively. The studied rock types are derived from partial melting of pre-existing crust indicated by (Y/Nb)N >0.18, (Th/Nb)N >2, (Ce/Pb)N <1, and (La/Nb)N >2 accompanied by the Eu, Ba, Sr, Ti, and Nb negative anomalies. The zircon U-Pb geochronology yielded emplacement ages of 1723 ± 16 Ma for the Sidhi granite gneiss and 1801 ± 64 Ma for the Madanmahal granite. Based on similar geochemical characteristics such as rare earth element patterns, Eu anomalies, and Ce/Pb, La/Nb, and Th/Nb ratios, we propose that the Sidhi granite gneiss and Madanmahal granite are derived from the same source i.e. Bundelkhand gneisses and granites, and formed in a post-orogenic rift environment of the accretionary orogen setting. [ABSTRACT FROM AUTHOR]

FeNdB magnets are one of the important secondary resources containing rare earth elements (REEs). The REEs present in FeNdB magnets can be separated from other metals by double salt precipitation. In order to recover pure Nd(III) solution from the double salts, separation experiments were done with the leaching solutions of the double salts containing Ce(III), Nd(III), and Pr(III). The REEs present in the double salts were completely dissolved using 0.5 M HCl solution at room temperature. First, Ce(III) was separated by oxidative precipitation of CeO2 and Ce(OH)4 by using NaClO and NaOH as an oxidizing and neutralizing agent. Complete separation of Ce(III) from the leaching solution of the double salts was possible by controlling solution pH at 5 under the following conditions: 11 for the molar ratio of NaClO/Ce(III) and 400 rpm at 40°C for 60 min. Second, all the Nd(III) and Pr(III) ions present in the filtrate were completely extracted by using saponified D2EHPA. Third, four stages of cross-current scrubbing of the loaded D2EHPA with pure Nd(III) solution removed most of the Pr(III) from the loaded D2EHPA. Finally, pure Nd(III) solution was obtained by stripping the scrubbed D2EHPA with weak HCl solution. The optimum conditions for the extraction, scrubbing, and stripping were obtained. A simple process was proposed to recover Nd(III) solution with purity higher than 99.9% from FeNdB magnets. [ABSTRACT FROM AUTHOR]

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. • Hydrogen transforms energy storage, promoting sustainability and innovation. • Research enhances nanostructured materials for hydrogen storage. • Hydrogen in IC engines explores dual fuel, HCCI, and RCCI. • Strategies like EGR and injection reduce hydrogen emissions. • Hydrogen shapes sustainable transportation solutions globally. [ABSTRACT FROM AUTHOR]

1H NMR measurements are reported for the C6D6 solution of the complex bis(tris(tert-butyl)cyclopentadienyl)neodymium(III) iodide [Cp′′′2NdI] {where Cp′′′ = 1,3,4-tris(tert-butyl)cyclopentadienide}. Temperature dependences of the 1H NMR spectra of the complex have been analyzed using the bandshape analysis, taking into account the temperature variation of the paramagnetic chemical shifts, within the frame of the dynamic NMR method. The conformational dynamics of the complex are conditioned by the process of racemization (with the value of the Gibbs activation energy ΔG ‡298 = 58 ± 3 kJ mol−1). Due to the substantial temperature dependence of the paramagnetic shifts, the complex is essentially an NMR thermosensor reagent for local temperature monitoring. Good agreement between the calculated and experimental lanthanide-induced paramagnetic shifts in the 1H NMR spectra indicates the similarity of the structure of the complex in a solution of C6D6 and the structure in the crystalline phase, found from the data of the X-ray structural study of the similar complex. [ABSTRACT FROM AUTHOR]

There is extensive geologic evidence of ancient volcanic activity on the Moon, but it is unclear how long that volcanism persisted. Magma fountains produce volcanic glasses, which have previously been found in samples of the Moon’s surface. We investigated ~3000 glass beads in lunar soil samples collected by the Chang’e-5 mission and identified three as having a volcanic origin on the basis of their textures, chemical compositions, and sulfur isotopes. Uranium-lead dating of the three volcanic glass beads shows that they formed 123 ± 15 million years ago. We measured high abundances of rare earth elements and thorium in these volcanic glass beads, which could indicate that such recent volcanism was related to local enrichment of heat-generating elements in the mantle sources of the magma. [ABSTRACT FROM AUTHOR]

In this study, we present the fabrication of large single-domain ternary (Sm,Eu,Gd)Ba 2 Cu 3 O 7-y bulk superconductor with enhanced superconducting properties using various REBa 2 Cu 3 O y (RE-123) as a liquid source via the top-seeded infiltration growth process (TSIG) in air. We employed a 1:1 ratio of REBa 2 Cu 3 O y (RE = Sm, Gd, Y and Er) and Ba 3 Cu 5 O 8 as a liquid source for fabrication. Impressively, all the obtained bulk samples exhibited a superconducting transition temperature T (c, onset) above 94 K. However, the bulk sample fabricated using Y-123 + Ba 3 Cu 5 O 8 as a liquid source demonstrated a T (c, onset) of 94.53 K, with a 40.14 % improvement in transition width (Δ T c) and at 77 K the bulk recorded a self-field critical current density (J c) value of 44.73 kA/cm2 & 10.62 kA/cm2 at 1T resulting in a remarkable 93.08 % improvement in self-field J c compared to the bulk sample fabricated using Er-123 + Ba 3 Cu 5 O 8. Microstructural analysis using a scanning electron microscope revealed a significant reduction in the mean size of secondary (211) phase particles, a significant reduction of 38.41 % is observed for the Y-123 + Ba 3 Cu 5 O 8 employed sample. [ABSTRACT FROM AUTHOR]

The reactions of rare earth elements (REEs) with refractory materials significantly affect their effective concentrations and inclusion modifications in molten steel. This study investigated the influence of steel-refractory reactions on the modification of inclusions in lanthanum-, cerium-, and yttrium-added steels utilizing three types of commonly used crucibles as smelting vessels. Steel-refractory reactions were found to strongly affect inclusions with different outcomes for smelting in MgO, Al 2 O 3 , and MgO·Al 2 O 3 crucibles. The RE-crucible reactions affected the evolution and size of inclusions in molten steel by influencing the content of [Mg] and [Al]. The RE-MgO crucible reactions increased [Mg] content, leading to more MgO inclusions and a smaller average size. The RE-Al 2 O 3 crucible reactions increased [Al] content, resulting in more REAlO 3 inclusions and a bigger average size. The reactions of La, Ce, and Y with MgO·Al 2 O 3 crucibles had varying effects on the evolution of inclusions. La and Ce selectively eroded the crucible, mostly reacting with the Al 2 O 3 component and generating REAlO 3 inclusions. In contrast, the slow reaction rate of Y with the crucible and the formation of the dense Y 2 O 3 layer at the steel/crucible interface made it react almost simultaneously with both MgO and Al 2 O 3 components, and the modification of inclusions was dominated by [Mg] rather than [Al]. The above conclusions provided more information on how the reactions between rare earth elements and refractory materials affected inclusions in rare earth steels during smelting. They also enriched the theory of inclusion control in steel and offered new controlling strategies. [ABSTRACT FROM AUTHOR]

Organic dyes, which are one of the main sources of surface and groundwater pollution, cause health problems as well as environmental hazards. For this reason, ZnO, which stands out among the promising semiconductor photocatalysts in wastewater treatment due to its advantages, was preferred. In particular, Gd–Ce co-doped ZnO nanostructured films, which have been studied for the first time in the literature, were produced by ultrasonic spray pyrolysis (USP) technique and photocatalytic degradation of Methylene blue (MB) dye was carried out. Ultraviolet–Visible Spectrophotometry (UV–Vis) and Field Emission Scanning Electron Microscopy (FESEM) were used to obtain the transmittance and morphology of thin films. According to the FESEM analysis results, morphological changes in the type of nanostructure were observed after the doping. While the photocatalytic degradation percentage of the ZnO film with Gd doping was 65.84 %, when both Gd and Ce were doped, the degradation percentage increased significantly, reaching 91.58 %. Photocatalytic studies revealed that Gd–Ce co-doped ZnO films exhibited better photocatalytic efficiency compared to only Gd doped ZnO films. Therefore, when all the results are evaluated, it is concluded that ZnO:Gd:Ce photocatalysts may have a significant potential application in environmental remediation. [ABSTRACT FROM AUTHOR]

As a special type of seep carbonate, the many details concerning the formation mode and mechanism of tubular seep carbonates are rarely reported. Here, new geochemical and mineralogical data regarding tubular seep carbonate (SQW-65) are reported. Sample SQW-65 had anomalously negative d13C values and positive d18Ovalues, which suggested the dissociation of gas hydrate. Additionally, almost all the sub-samples showed no Ce anomaly (Ce/Ce*average = 0.93), with obvious U enrichment (21.3< UEF <240.3), which indicates that the studied tubular seep carbonate was formed in an anoxic environment. Subsequently, the formation process of the studied tubular seep carbonate is further discussed according to the variability of mineralogical and geochemical characteristics from the rim to the core of the tubular formation. In the early stage of the studied tubular seep carbonate (periphery), owing to the influence of terrigenous components, the quartz and Ti content and Y/Ho ratio were high. However, with the formation of the periphery, the influence of terrigenous components was gradually weakened. In addition, from the rim to the core, the carbon and oxygen isotope values showed a "covariation" coupling relationship, an enrichment of U, and a reduction in total rare earth element content. This is because as the outer wall thickens and the internal fluid channel narrows, the intensity of the sulphatedriven anaerobic oxidation of methane and the associated precipitation rate of carbonate also increase. [ABSTRACT FROM AUTHOR]

ABSTRACT Milk, owing to its nutritional value, is a staple commodity in daily life. Ensuring its integrity and authenticity is paramount for researchers and the food industry. To evaluate spoilage and adulteration of milk, we proposed a robust and reliable optical method to guarantee milk quality by utilizing riboflavin as an internal biomarker. By precisely controlling the content of Eu3+, Tb3+, and Gd3+ ions, a two‐dimensional ratiometric luminescence lanthanide coordination polymer (Ln‐CP) with adjustable emission centers was synthesized for the detection of riboflavin (RF), leveraging a Förster resonance energy transfer (FRET) and photoinduced electron transfer (PET) process. This method demonstrates high sensitivity and selectivity towards RF and has been successfully applied to the detection of RF in both milk and calf serum. [ABSTRACT FROM AUTHOR]

Binary systems of lanthanide ions (La, Nd, Gd, Ho, Tb, and Lu) with L-malic acid in molar ratios of 1:1 and 1:2 were studied. This study was carried out in aqueous solutions, and the composition of the formed complexes was confirmed using computer data analysis. The overall stability constants of the complexes and the equilibrium constants of the reaction were determined. The effect of ligand concentration on the composition of the internal coordination sphere of the central atom was observed. Changes in the coordination sphere of lanthanide ions were confirmed by spectroscopic measurements. [ABSTRACT FROM AUTHOR]

The aim of the research was to assess the potential of bottom ash from Polish coal-fired power plants as an alternative source of rare earth elements (REY). The potential of these ashes was compared with fly ash from the same coal combustion cycle. The phase and chemical composition, as well as REY, were determined using: X-ray diffraction and inductively coupled plasma mass spectrometry. The tested ashes were classified as inert-low pozzolanic and inert-medium pozzolanic, as well as sialic and ferrosialic, with enrichment in detrital material. The phase and chemical composition of bottom ash was similar to fly ash from the same fuel combustion cycle. The REY content in the ash was 199–286 ppm and was lower than the average for global deposits, and the threshold value was considered profitable for recovery from coal. Bottom ash's importance as a potential source of REY will increase by recovering these metals from separated amorphous glass and mullite and grains rich in Al, Mg, K, and P. The industrial value of bottom ash as an alternative source of REY was similar to fly ash from the same fuel combustion cycle. [ABSTRACT FROM AUTHOR]

Mg-Gd-Y-Zn-Mn (MVWZ842) is a kind of high rare earth magnesium alloy with high strength, high toughness and multi-scale strengthening mechanisms. After heat treatment, the maximum tensile strength of MVWZ842 alloy is more than 550 MPa, and the elongation is more than 5%. Because of its great mechanical properties, MVWZ842 has broad application potential in aerospace and rail transit. However, the addition of high rare earth elements makes the deformation resistance of MVWZ842 alloy increase to some extent. This leads to the difficulty of direct plastic processing forming and large structural part shaping. Friction stir welding (FSW) is a convenient fast solid-state joining technology. When FSW is used to weld MVWZ842 alloy, small workpieces can be joined into a large one to avoid the problem that large workpieces are difficult to form. In this work, a high-quality joint of MVWZ842 alloy was achieved by FSW. The microstructure and properties of this high-strength magnesium alloy after friction stir welding were studied. There was a prominent onion ring characteristic in the nugget zone. After the base was welded, the stacking fault structure precipitated in the grain. There were a lot of broken long period stacking order (LPSO) phases on the retreating side of the nugget zone, which brought the effect of precipitation strengthening. Nano-α-Mn and the broken second phase dispersed in the matrix in the nugget zone, which made the grains refine. A relatively complete dynamic recrystallization occurred in the nugget zone, and the grains were refined. The welding coefficient of the welded joint exceeded 95%, and the hardness of the weld nugget zone was higher than that of the base. There were a series of strengthening mechanisms in the joint, mainly fine grain strengthening, second phase strengthening and solid solution strengthening. [ABSTRACT FROM AUTHOR]

As the 21st century advances, the demand for rare earth elements (REEs) is rising, necessitating more robust exploration methods. Our research group is using hyperspectral remote sensing as a tool for mapping REEs. Unique spectral features of bastnaesite mineral, has proven effective for detection of REE with both spaceborne and airborne data. In our study, we collected hyperspectral data using a Senop hyperspectral camera in field and a SPECIM hyperspectral camera in the laboratory settings. Data gathered from California's Mountain Pass district revealed bastnaesite-rich zones and provided detailed insights into bastnaesite distribution within rocks. Further analysis identified specific bastnaesite-rich rock grains. Our results indicated higher concentrations of bastnaesite in carbonatite rocks compared to alkaline igneous rocks. Additionally, rocks from the Sulphide Queen mine showed richer bastnaesite concentrations than those from the Birthday shonkinite stock. Results were validated with thin-section studies and geochemical data, confirming the reliability across different hyperspectral data modalities. This study demonstrates the potential of drone-based hyperspectral technology in augmenting conventional mineral mapping methods and aiding the mining industry in making informed decisions about mining REEs efficiently and effectively. [ABSTRACT FROM AUTHOR]

Rare earth and transition metal ion-doped CaZnOS has garnered significant attention for its exceptional mechanoluminescence (ML) performance under mild mechanical stimuli and its capability for multicolor emissions. Since powdered phosphors are not directly usable, they require encapsulation within with polymers to create stable structures. This study investigates Mn2+-doped CaZnOS (CaZnOS:Mn2+) as the ML phosphor, optimizing its performance by varying the Mn2+ content, resulting in bright orange-red emissions from the d-d transitions of the Mn2+ activator. A quantum efficiency of 59.08% was achieved through the self-sensitization of the matrix lattice and energy transfer to the Mn2+ luminescent centers. The enhancement in ML due to Mn2+ doping is attributed to the reduced trap depth and increased trap concentration. Encapsulation with four polymers—PDMS, PU, SIL, and RTV-2—was explored to further optimize ML performance. Among these, PDMS provides the best ML output and sensitivity, owing to its slightly cross-linked structure and good triboelectric properties. The optimized CaZnOS:0.03Mn2+/PDMS composite, featuring excellent flexibility and recoverability, shows great potential for applications in anti-counterfeiting encryption, stress sensors, and wearable devices. [ABSTRACT FROM AUTHOR]

• Pigment provenance research is a promising direction in cultural heritage research. • Usually, only traces of the original polychromy of Greek and Roman art remain – to keep the impact to a minimum, new sampling methods for pigment provenance research are needed. • This work shows that easily available tools provide comparable (cotton swabs vs scalpel) geochemical results for pigment provenance research. Mineral pigment provenance is a promising direction in cultural heritage particularly in ancient polychromy research. The analysis of trace elements and Pb-isotopes can provide clues about the origin of pigment raw materials. While previous investigations already showed great potential for provenancing archeological-historical mineral pigments, sampling methods and reference data collections need to be developed further to evaluate the potential and limitations of this type of research. This work tests a new sampling method for pigment provenance research that collects sample material with easily available (suffused) cotton swabs for analysis by mass spectrometry. Three artifacts decorated with Egyptian blue and red pigments were selected for comparing sampling with cotton swabs to sampling with a scalpel. All three artifacts date to the 1st century BCE: The first is a colossal marble head from Lazio, Italy, which probably belonged to a seated cult statue of Zeus, and with extensive remains of ancient red paint. The two artifacts (a slag and a fragment of a terracotta vessel) were recovered during Petrie's excavations of an Egyptian blue production facility in Memphis, Egypt. The new results are consistent with previous studies, which provides the necessary quality control for the cotton swab sampling method. This work contributes to improving sampling methods for pigment provenance analysis as well as to a better understanding of past pigment production and trade networks. [ABSTRACT FROM AUTHOR]

Colorants used in security inks are special pigments that radiate in the UV region or IR region. Obtained pigments can be from valuable rare earth elements or they can be organic based. Organic-based pigments are generally insoluble in water, which limits their use. For this purpose, an organicbased UV-radiating pigment was synthesized and made water-soluble by forming its salt. With the obtained salt-formed pigment, inkjet ink that can be used in counterfeiting was applied and its printability and resistance properties were determined. In this study, 1, 3, 6, 8-pyrene sulfonic acid tetrasodium salt was synthesized and water-based inkjet inks with hydroxy ethyl cellulose binder were produced. The prepared inks were printed on the paper surface. The color and gloss of the prints obtained were measured both in the visible region and in the UV region. Its optical properties were detected by UV spectroscopy. Strength properties such as light fastness, nitro resistance, alkali resistance, acid resistance, rub resistance, drying time, adhesion and dry film weight of the prints were determined. As a result; Inkjet ink with 1, 3, 6, 8-pyrene sulfonic acid tetrasodium salt was produced and it was concluded that it has good resistance properties. [ABSTRACT FROM AUTHOR]

The origin of magmatic microgranular enclaves has been investigated in the Mesoproterozoic granitoid Krasnopol intrusion (1.5 Ga), part of the AMCG (anorthosite–mangerite–charnockite–granite) Mazury Complex in the East European Craton (NE Poland). The granitoids are ferroan and metaluminous, and display the typical characteristics of A-type granites, with high contents of Zr, Nb, Ga and rare earth elements (REEs). The enclaves are metaluminous and have a broad compositional range with two groups distinguished: silica-poor (45–50 wt% SiO2) and silica-rich (54 to 59 wt% SiO2), the latter overlapping in composition with the granitoid samples. The silica-poor enclaves are enriched in REEs compared to the silica-rich type, while the silica-rich enclaves exhibit trace-element patterns similar to those of the granitoids. Initial whole rock εNd values range between -3.8 and -4.0 for the granitoids and give a slightly wider range from -2.6 to -3.8 for the enclaves. The 87Sr/86Sr initial values vary from 0.7084 to 0.7138 for the granitoids and between 0.7052 and 0.7075 for the enclaves and indicate that the granitoids and enclaves are not isotopically identical. These may suggest that the two magmatic systems represented by the granitoid host rock and the enclaves, were probably derived from different sources, but with sufficient interaction, which led to a progressive change in the composition of the enclaves towards intermediate composition. We suggest that the mafic melts of the enclaves were generated at the base of the thickened crust through partial melting of the lower crustal source, with a significant contribution from mantle material. The increase in temperature resulted in anatexis of the lower crust and the formation of the granitoid parental magma. [ABSTRACT FROM AUTHOR]

In this study, laser ablation–multicollector–inductively coupled plasma–mass spectrometry (LA–MC–ICP–MS) of apatites and LA–ICP–MS of zircons are used to collect U–Pb geochronological data, Rb–Sr isotope chronology is used to analyze alkaline feldspar and plagioclase, and archival apatite geochemistry data for the exposed Naitoushan basalt and Heishigou dike in the Changbaishan Tianchi volcano (CTV) are accessed to examine the petrogenesis and determine the origin of basaltic magmatism in the CTV. The Naitoushan basalt and Heishigou dike formed at 22.2–18.7 and 0.230–0.218 Ma, respectively. In situ oxides, volatiles, trace element geochemistry and Sr–Nd isotopes of apatite are reported for two samples. Most apatites are in the early crystallization phase and form inclusions in plagioclase that are euhedral or subhedral. They have higher MgO and K2O/Na2O concentrations; lower F and Cl concentrations; Ba, Sr, Nb, Ta, Zr, Hf, K, and Ti depletion; and Th, U, Ce, Pb, P, and Nd enrichment. All apatite samples are enriched in light rare earth elements (REEs) relative to heavy REEs and have relatively homogeneous Th/U, Zr/Hf, La/Sm, and Nd/Tb ratios and Sr–Nd isotopic compositions; thus, their host magmas potentially have the same magmatic origin as oceanic island basalt. The apatite La, Yb, and U contents, Eu/Eu* and La/Yb values, and high REE contents show a weak crystallization sequence in the mafic magma. This study demonstrates that the pre-shield and post-shield mafic magmas in the CTV were likely derived from an enriched mantle source with an I-type signature related to the rollback of the Pacific plate. [ABSTRACT FROM AUTHOR]

Seven experiments exploring the reaction of titanite with various hydrothermal solutions have been carried out at 700 °C and 200 MPa for a run duration of 16 days. In experiments involving fluids consisting of NaCl+H2O, KCl+H2O, CaCl2+H2O, 2M NaOH, or 2M KOH, no reaction of the titanite with the fluid was observed other than a slight dissolution of the titanite. Experiments involving NaF+H2O and Ca(OH)2+H2O resulted in visible alteration of the titanite in texture and composition, coupled with the formation of perovskite. In the NaF+H2O experiment, perovskite, enriched with rare earth elements (REE), formed as euhedral to subhedral crystals on the surface of the recrystallized titanite. In the Ca(OH)2+H2O experiment perovskite took in minor amounts of REE, and formed as a reaction rim partially replacing the titanite via a coupled dissolution-reprecipitation reaction. Wollastonite, along with minor calcite, and grossular garnet, formed as an outer rim on the perovskite. In the NaF+H2O experiment major and trace elements were leached from the titanite, whereas in the Ca(OH)2+H2O experiment no leaching of major or trace elements was observed. Nb/Ta, Th/U, and Y/Ho were investigated as potential indicators of hydrothermal processes. While the Nb/Ta ratio was altered in the experimentally metasomatised titanite, the degree of alteration was the same for both fluids. In contrast, only small changes in the Th/U and Y/Ho ratios between the altered and original titanite were seen for either experiment. The formation of perovskite at the expense of titanite in NaF+H2O or Ca(OH)2+H2O fluids demonstrates how titanite reacts with these fluids in simple, low silica activity systems under mid to upper crustal P-T conditions. [ABSTRACT FROM AUTHOR]

Potassium sodium niobate (KNN)‐based piezoelectric ceramics have emerged as a promising alternative to lead‐based systems due to their exceptional properties. While extensive research has focused on improving the electrical properties of KNN‐based ceramics through doping and processing optimization, the concurrent investigation of their mechanical properties has been lacking. This study presents a comprehensive analysis of the mechanical and electrical properties of KNN‐based lead‐free piezoceramics doped with various transition metal oxides and rare earth oxides, based on substantial experimental data. Our findings reveal that the as‐sintered KNN‐based ceramics exhibit not only outstanding electrical properties but also remarkable mechanical robustness compared to conventional toughened lead zirconate titanate (PZT)‐based ceramics. These exceptional electrical and mechanical properties are attributed to the micro‐scale and atomic‐scale structure of the modified KNN‐based ceramics, characterized by a highly condensed structure, an inhomogeneous distribution of nano‐domain structure, and the presence of amorphous intergranular films at grain boundaries. [ABSTRACT FROM AUTHOR]

Tangshan is known as a typical heavy industrial city with serious atmospheric pollution. It suffers the most serious atmospheric pollution during the winter heating period. This study aims to explore the level and spatial distribution of atmospheric element deposition in the study area and validate the suitability of Ramalina sinensis (RSI) as an active biomonitor in North China cities. RSI was transplanted to Tangshan in winter (Dec. 2016- Mar. 2017) and exposed for 17 weeks. The concentration of 51 elements was tested using an ICP-MS (inductively coupled plasma mass spectrometer). The results showed that the exposure concentration of all elements but Ag was significantly higher than the background value. Principal component analysis (PCA) showed that K, P, and Rb were separated into the group G5, and these nutrients have a lower level of bioaccumulation than other groups. The remaining 47 elements were classified into groups G1 (Al, Be, Co, Cr, Cs, Ge, Li, Nb, Ni, Si, Th, Ti, U, V, and 16 rare earth elements La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Y, and Sc) of crustal origin, G2 (Ca, Cd, Cu, Mg, Mn, Mo, S, Sb, Sr, and Zn) and G3 (Bi, Pb, and Sn) of atmospheric origin, and G4 (As, Fe, Se, and Tl) of crustal-atmospheric origin. The overall bioaccumulation in Tangshan is moderate (PLIzone = 2.010 for the combined groups G1-4), with the highest bioaccumulation level (high to severe) for the atmospheric group G2. The most concerned elements are Ca and S, which are of high bioaccumulation at the regional scale. All element groups show a similar spatial pattern characterized by decreasing atmospheric deposition from east to west and from rural to urban areas. These results indicate that RSI is a good active biomonitor for most elements, barring some nutrients. The importance of G2 elements should be emphasized as an indicator of anthropogenic emissions in lichen-active biomonitoring techniques in North China cities. The study area experienced a certain degree of atmospheric pollution, contributed mainly by the frequent industrial and agricultural activities and coal combustion for heating in the east of the city and the rural areas around. This study is the first to monitor atmospheric deposition in industrial cities in North China using the active lichen biomonitoring method. [ABSTRACT FROM AUTHOR]

Recovery of rare earth elements (REEs) from spent NdFeB magnets is important to meet the increasing demand for magnets and high-tech applications. In general, pretreatments of spent NdFeB magnets are necessary to recover REEs such as Nd, Pr, and Ce from the magnets. In this work, a simple process was proposed to recover REEs without any pretreatment of NdFeB magnets by using precipitation of REE(III) double salt. The correlations among several variables on the precipitation of REE(III) double salt were investigated by using synthetic solutions such as the molar ratio of Na(I) and sulfuric acid to Nd(III), the concentration of Nd(III) and Fe(III). The REES and iron present in NdFeB magnets were completely dissolved in 2 M H2SO4 solution at room temperature. The dissolved REE(III) ions were then directly separated by precipitation of double salt when Na2SO4 was added at 80°C. After REEs precipitation, the addition of iron powder to the filtrate at room temperature reduced Fe(III) to Fe(II) and removed a small amount of Cu(II) and Co(II) by cementation. Then Fe(II) and Na2SO4 were separated by precipitation of Fe(OH)2 when solution pH was adjusted to 8. The conditions for the precipitation of Nd(III) double salt were thermodynamically verified. Mass balance of continuous experiments indicated that it was possible to recover REEs and iron with high purity by the proposed process in this work. [ABSTRACT FROM AUTHOR]

The large loss of fine-grained bastnaesite has become an increasingly important issue restricting the development of rare earth ore flotation industry. To solve this issue, a new collector mixture that combines octyl hydroxamic acid (OHA) and octyl phenol ethoxylation (OP10, the number of ethylene oxide groups is 10) is proposed to be used to improve the flotation of bastnaesite. The flotation adsorption mechanism of OHA/OP10 on bastnaesite was investigated by a series of experimental and analytical tests. The results showed that when the molar ratio of OHA/OP10 was 3:1, the OHA/OP10 combination significantly improved the recovery of −74 + 38 μm and −15 μm bastnaesite compared with only OHA. Optical microscopy revealed that mixed OHA/OP10 had a beneficial effect on fine-grained bastnaesite aggregation. In addition, the results of the zeta potential test, fluorescence spectrum analysis, and XPS analysis showed that OHA and OP10 were co-adsorbed on the surface of bastnaesite. [ABSTRACT FROM AUTHOR]

For photocatalysis technology to be applied industrially, there has been a significant increase in the need for visible-light-driven photocatalysts that possess exceptional superparamagnetic characteristics to facilitate easy separation. Hence, in this study, rare earth elements (RE) (Sm, Yb, Dy, Er, and Ho) were systematically doped into manganese ferrite (MF) using the coprecipitation method to serve two purposes, namely, reducing the photogenerated electron-hole recombination during photocatalysis and modifying the magnetic properties of MF to become superparamagnetic. The synthesised Re-doped MF was found to be visible light active, as evidenced by the transient photocurrent response and the obtained band gaps, which were in the range of 1.84–1.93 eV. From the cyclic voltammetry, electrochemical impedance spectroscopy, and Tafel polarization plots, it was evident that different RE element dopants have different effects on improving the electrochemical properties of MF. Overall, fast electron transfer of the synthesised materials was found to decrease in the following order: Sm-MF > Dy-MF > Ho-MF > MF > Er-MF > Yb-MF. The g-factor and peak-to-peak line width were found to be in the range of (2.221–2.317) and (93.17–149.85 mT), respectively. The resonance field and hysteresis loop (H c) were found to be in the range of (289.2–301.86 mT) and (8.24–32.61 mT), respectively. Overall, the synthesised RE-doped MF exhibits ferromagnetic properties, and the obtained small H c values hint at these particles exhibiting superparamagnetic properties. In summary, doping MF with Sm, Dy, and Ho is more desirable as it alters the magnetic properties towards superparamagnetic and improves its electrochemical properties. Thus, this study is of importance in advancing the field of photocatalysis in water treatment and material science. • RE (Sm, Dy, Ho, Er, and Yb) were successfully incorporated into the MF spinel structure. • Sm, Dy and Ho dopants improved the electrochemical and optical properties of MF. • The magnetic properties of MF were improved. • The produced photocatalysts were visible light active. [ABSTRACT FROM AUTHOR]

The present work includes the use of effective strategy to improve the photocatalytic degradation activity of CdAl 2 O 4 via dopant assimilation to enhance the bandgap energy (E g) and to influence the light-sensitive activity of this spinel mixed oxide. In this study, CdAl 2 O 4 (CA), Mg–CdAl 2 O 4 (MCA), and Tb-doped Mg–CdAl 2 O 4 (TMCA) were fabricated by the facile co-precipitation route and an ultra-sonication approach was used to prepare a composite of Tb-doped Mg–CdAl 2 O 4 with MXene (TMCA@MXene). The obtained results from UV–Visible analysis deduce that there is an increase in E g of MCA (2.51 eV) and TMCA (2.67 eV) as compared to pure CA (2.45 eV) which follows the quantum confinement effect accompanying the decrease in crystallite sizes of doped samples as compared to CA. The significant increase in bandgap energy of TMCA is due to the confinement of electrons in a small area and also due to the conversion of continuous energy levels into discrete energy levels. Moreover, UV–Visible spectroscopic analysis was made to evaluate the catalytic performance of fabricated photocatalysts against harmful organic pollutants. The photocatalytic study showed that the co-doped CdAl 2 O 4 (TMCA) is a better photocatalyst than MCA and CA for the degradation of selected pollutants. Among all synthesized catalysts i.e. CA, MCA, TMCA, and TMCA@MXene, the highest photocatalytic activity was shown by MXene based nanocomposite. TMCA@MXene showed ∼86 % degradation of Rhodamine B (RhB) and 79.6 % degradation of Aspirin (acetylsalicylic acid). The outstanding photocatalytic efficacy of TMCA@MXene could be accredited to the quantum confinement effect produced by co-doping of alkaline earth metal (Mg+2) and rare earth metal (Tb+3) and large surface area, high conductivity, and excellent light harvesting capability provided by MXene sheets. Hence, TMCA@MXene could be an effective photocatalyst in future for the removal of toxic organic pollutants. [ABSTRACT FROM AUTHOR]

The sorption of certain lanthanides from aqueous solutions is the focus of this work using antimony oxide (Sb2O5) sorbent. Sb2O5 sorbent was prepared using the precipitation technique, and it has been described using several analytical methods such as Fourier-transformed infrared (FT-IR), X-ray diffraction pattern (XRD), and scanning electron microscope (SEM). The sorption data were collected on Y(III), Ce(III), and Gd(III) including the effects of pH, shaking time, initial metal concentrations, and temperature. The results revealed that saturation capacity has values of (30.6, 27.5, and 24.1 mg/g) for Y(III), Ce(III), and Gd(III), respectively. The sorption of the studied cations is dependent on pH. The reaction kinetics obeyed the pseudo-2nd-order model, and thermodynamics was endothermic and spontaneous. Sorption isotherms are more relevant to a Langmuir isotherm, whose monolayer capacity values are 27.9, 23.2, and 19.8 mg/g for Y(III), Ce(III), and Gd(III), respectively. The real sample applications illustrate the superiority of antimony oxide sorbent in the removal of Y(III), Ce(III), and Gd(III) from high-grade monazite (HGM). [ABSTRACT FROM AUTHOR]