Rare-Earth Elements
O2. Graph showing radii of the trivalent ions of the rare-earth elements as well as of cerium in the +4 valence state and europium in the +2 valence state ..... O6 O3. Photograph of the Mountain Pass Mine in San Bernardino County, California, which was the only active producer of rare-earth elements in the United States
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Properties, Compounds, and Complexes of Rare Earth …
The rare earth elements comprise Sc, Y, and the lanthanide elements (La–Lu). Their physical properties and physicochemical behaviors are determined by the characteristics of their atomic electron layer arrangements (Gschneidner 1990).Several lists in this section give the characteristics of the atomic structure of rare earth elements and …
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Extraction and complexation of trivalent rare earth …
Rare earth elements (REEs) consist of 15 lanthanides along with scandium and yttrium. Due to their special chemical, catalytic, electrical, magnetic and optical …
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Rare Earth Element
The ionic radii of trivalent REE ions are about 1 ... Rare earth element mining projects are characterized by specific particularities as well as the potential presence of radiation. Thus, there is a need for a set of REE-specific criteria and indicators to supplement Global Reporting Initiative–based indicators. This chapter identifies ...
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Separation of trivalent rare earths from nitrate medium …
By introducing the amine group into the structure of P227, a novel extractant 2-ethylhexyl ((2-ethylhexylamino)methyl) phosphonic acid (EEAMPA, abbreviated as HA) was synthesized for the extraction and separation of trivalent rare earths (REs) from nitrate medium. The influence factors including extractant concentration, equilibrium time, HNO …
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Phase Equilibria in Systems Involving the Rare-Earth Oxides.
Templeton and Dauben have calculated ionic radii of the rare-earth ions using a value of 0.21441 a (for the C-type rare-earth oxide structure) for the cation-oxygen distance. They emphasize that the relative difference between any two trivalent rare-earth cations can be found much more accurately than the absolute radii.
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Understanding the valency of rare earths from first …
Most of the rare-earth atoms are divalent, but generally become trivalent in the metallic state. In some materials, the energy difference between these valence states …
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Advances in Rare‐Earth Tritelluride Quantum Materials: …
Most rare-earth elements form RTe 3 layered structures (Figure 1a), and all RTe 3 compounds have trivalent ion configurations. It is also noteworthy to mention that Pm from the lanthanide series is radioactive as such realizing PmTe 3 is practically impossible even though Pm is likely to form PmTe 3 from a chemical perspective. Similarly, the …
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On the Hydration of the Rare Earth Ions in Aqueous Solution
The rare earth perchlorate solutions of Eu(ClO 4) 3, Gd(ClO 4) 3, Tb(ClO 4) 3 and Dy(ClO 4) 3 were produced from their oxides which were dissolved with perchloric acid. The rare earth oxides were purchased from Sigma–Aldrich (now Merck, Darmstadt, Germany) at 99.9% purity on trace metal basis, except Tb 2 O 3 with a purity of 99.99%. …
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The Smaller the Better: Hosting Trivalent Rare-Earth …
Placing trivalent rare-earth cations inside fullerene molecules or in between blocks of intermetallics has given rise to a plethora of fascinating properties and …
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Rare-earth element
Rare-earth element - Properties, Metals, Uses: As noted above, the rare-earth elements—especially the lanthanides—are quite similar. They occur together in nature, and their complete separations are difficult to achieve. …
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Synthesis and Characterization of the Rare-Earth Hybrid …
Two hybrid rare-earth double perovskites, (CH3NH3)2KGdCl6 and (CH3NH3)2KYCl6, have been synthesized by a solution evaporation method and their structures determined by variable temperature single-crystal X-ray diffraction. The diffraction results show that at room temperature both perovskites adopt a rhombohedral structure …
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Acid Dissociation Constants and Rare Earth Stability
As a result, much attention has been paid to the characterization of the molecule and its metal complexes. Previous studies have reported pK a values for DTPA and stability constants for rare earth and trivalent actinide (Cm–Fm) DTPA complexes [17–25]. The most complete values for the latter are reported at 0.1 and 0.5 mol·L −1 ionic ...
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Extraction and complexation of trivalent rare earth …
1. Introduction. Rare earth elements (REEs) consist of 15 lanthanides along with scandium and yttrium. Due to their special chemical, catalytic, electrical, magnetic and optical properties, they have been widely used in petroleum, metallurgy, textiles, agriculture and electronics industry [1].However, because of the scarcity of REEs resources in the …
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ENZYMOLOGY Trivalent rare earth metal cofactors …
Trivalent rare earth metal cofactors confer rapid NP-DNA polymerase activity Victor S. Lelyveld1,2, Ziyuan Fang1,2,3, Jack W. Szostak1,2,3,4,5,6* A DNA polymerase with a single mutation and a divalent calcium cofactor catalyzes the synthesis of unnatural N3′→P5′ phosphoramidate (NP) bonds to form NP-DNA. However, this template-directed
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Solubility products of the trivalent rare-earth phosphates
@article{osti_5838290, title = {Solubility products of the trivalent rare-earth phosphates}, author = {Firsching, F and Brune, S N}, abstractNote = {This paper reports on the solubility and solubility products of 14 rare-earth phosphates in aqueous solution that have been determined at 25 {plus minus} 1{degree} C. The most soluble compound is …
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Experimental study of trivalent rare-earth element …
When doped with a trivalent rare-earth element (REE), this material exhibits interesting luminescence properties (de Figueiredo et al. 2007; Mazzo et al. 2010; Ribeiro …
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Rare-earth element
The rare earths are generally trivalent elements, but a few have other valences. Cerium, praseodymium, and terbium can be tetravalent; samarium, europium and ytterbium, on the other hand, …
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An Updated Review of Toxicity Effect of the Rare Earth …
Literature related to rare earth elements was searched in PubMed, Science Direct, and Google Scholar, and the number of literatures was then broken down according to the year. (B) Pie chart summarized the number of literatures for each rare earth element (REEs) eco-toxicity test from 1985–2019. The number of literatures was then broken …
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Rare earth (RE) doped phosphors and their emerging …
For trivalent rare earth, La 3+ and Y 3+ are mainly used as inactive host cations in most of the phosphor [41, 42]. Depending on the ionic radii, most of the RE ions acquire the greatest array of coordination numbers (CN) from 6 …
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An overview of rare earth coupled lead halide perovskite …
As for the location of rare-earth ions, many studies find that trivalent lanthanide cations are also preferentially adsorbed on the surfaces and grain boundaries of perovskite films serving as a passivation layer, and only a small amount may incorporate into the perovskite lattice in substitution of Pb 2+ ions.
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The Recovery of Rare Earth Elements (REEs) from Aqueous
Increasing applications of rare earth elements (REEs) and improving technologies have led to increased demand. Because of their limited availability and depletion of most resources, the recovery of these elements from waste has become important. The use of cost-effective materials for this purpose and the high value that can …
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Rare Earth Magnetic Materials | SpringerLink
The magnetic moment of non-trivalent rare earth ions are basically the same or close to that of isoelectronic trivalent ions. The magnetic moment of Pr 4+ is 2.48 B.M., similar to that of isoelectronic Ce 3+ (2.56 B.M.), but the magnetic moment of Ce 4+ is not zero as for La 3+, which is an exception.
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Special Issue: Rare earth luminescent materials
Trivalent rare earth ions (Ln 3+) have the unique electronic configurations [Xe]4f n ( n = 0–14) and numerous energy levels, which endow rare earth luminescent …
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Understanding the valency of rare earths from first …
In the trivalent rare-earth sulphides, there are three electrons available for bonding. Again, two of these hybridize with the sulphur 3 p bands and fill them, but this still leaves one electron ...
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Rare earths | Institute for Rare Earths and Metals
Most trivalent rare earth metals have room temperature values from about 60 to 90 μΩ-cm. The low value of 25 μΩ-cm is for divalent fcc-ytterbium metal, while the two largest values, gadolinium (131 μΩ-cm) and terbium (115 μΩ-cm), are due to a magnetic contribution to electrical resistance, the arises near the magnetic order temperature ...
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Trivalent rare earth metal cofactors confer rapid NP …
Trivalent rare earth metal cofactors confer rapid NP-DNA polymerase activity. Victor S. Lelyveld, Ziyuan Fang, and Jack W. Szostak Authors Info & Affiliations. Science. 26 Oct 2023. Vol 382, Issue 6669. pp. 423 - 429. DOI: …
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Rare earth ion conduction in solids
The trivalent rare earth ion conduction in tungstates and molybdates with Sc 2 (WO 4) 3 type structure was directly demonstrated by the dc electrolysis, and Sc 2 (WO 4) 3 and Sc 2 (MoO 4) 3 were found to possess the highest conductivity among each solid electrolyte series, respectively.
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Advancing Rare-Earth Separation by Machine Learning
Herein, we report an in-depth study on selectivity and speciation in the extn. of the trivalent minor actinide Am and rare earth metal ions with a pre-organized phenanthroline-based ligand in a hydrocarbon solvent system relevant to nuclear fuel reprocessing. The 1 : 1 and 2 : 1 ligand-to-metal complexes dominate the speciation in the org ...
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Lanthanide Rare Earths | SpringerLink
The mostly trivalent rare earth elements (REE) are arguably the most significant group of trace elements in geochemistry. The lanthanide series develops by filling 4f orbitals, which do not effectively shield each other from increasing nuclear charge, leading to highly coherent geochemical behavior as a group.
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