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At least 1,243 records · Page 69
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DOE OSTI2020

Materials Data on K3Dy by Materials Project

K3Dy is beta Cu3Ti-like structured and crystallizes in the hexagonal P6_3/mmc space group. The structure is three-dimensional. K is bonded to eight equivalent K and four equivalent Dy atoms to form distorted KK8Dy4 cuboctahedra that share corners with four equivalent DyK12 cuboctahedra, corners with fourteen equivalent KK8Dy4 cuboctahedra, edges with six equivalent DyK12 cuboctahedra, edges with twelve equivalent KK8Dy4 cuboctahedra, faces with four equivalent DyK12 cuboctahedra, and faces with sixteen equivalent KK8Dy4 cuboctahedra. There are a spread of K–K bond distances ranging from 4.19–4.42 Å. There are two shorter (4.29 Å) and two longer (4.30 Å) K–Dy bond lengths. Dy is bonded to twelve equivalent K atoms to form DyK12 cuboctahedra that share corners with six equivalent DyK12 cuboctahedra, corners with twelve equivalent KK8Dy4 cuboctahedra, edges with eighteen equivalent KK8Dy4 cuboctahedra, faces with eight equivalent DyK12 cuboctahedra, and faces with twelve equivalent KK8Dy4 cuboctahedra.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on DyScZn2 by Materials Project

DyScZn2 is Heusler structured and crystallizes in the cubic Fm-3m space group. The structure is three-dimensional. Dy is bonded in a body-centered cubic geometry to eight equivalent Zn atoms. All Dy–Zn bond lengths are 3.00 Å. Sc is bonded in a body-centered cubic geometry to eight equivalent Zn atoms. All Sc–Zn bond lengths are 3.00 Å. Zn is bonded in a body-centered cubic geometry to four equivalent Dy and four equivalent Sc atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Nd3Dy by Materials Project

DyNd3 is beta Cu3Ti-like structured and crystallizes in the hexagonal P6_3/mmc space group. The structure is three-dimensional. Dy is bonded to twelve equivalent Nd atoms to form DyNd12 cuboctahedra that share corners with six equivalent DyNd12 cuboctahedra, corners with twelve equivalent NdNd8Dy4 cuboctahedra, edges with eighteen equivalent NdNd8Dy4 cuboctahedra, faces with eight equivalent DyNd12 cuboctahedra, and faces with twelve equivalent NdNd8Dy4 cuboctahedra. There are six shorter (3.66 Å) and six longer (3.67 Å) Dy–Nd bond lengths. Nd is bonded to four equivalent Dy and eight equivalent Nd atoms to form NdNd8Dy4 cuboctahedra that share corners with four equivalent DyNd12 cuboctahedra, corners with fourteen equivalent NdNd8Dy4 cuboctahedra, edges with six equivalent DyNd12 cuboctahedra, edges with twelve equivalent NdNd8Dy4 cuboctahedra, faces with four equivalent DyNd12 cuboctahedra, and faces with sixteen equivalent NdNd8Dy4 cuboctahedra. There are a spread of Nd–Nd bond distances ranging from 3.65–3.68 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Dy4Rh by Materials Project

Dy4Rh is Iron carbide-like structured and crystallizes in the cubic Fd-3m space group. The structure is zero-dimensional and consists of eight Dy4Rh clusters. Dy is bonded in a single-bond geometry to one Rh atom. The Dy–Rh bond length is 2.58 Å. Rh is bonded in a tetrahedral geometry to four equivalent Dy atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on DyTmIr2 by Materials Project

TmDyIr2 is Heusler structured and crystallizes in the cubic Fm-3m space group. The structure is three-dimensional. Tm is bonded in a body-centered cubic geometry to eight equivalent Ir atoms. All Tm–Ir bond lengths are 2.95 Å. Dy is bonded in a body-centered cubic geometry to eight equivalent Ir atoms. All Dy–Ir bond lengths are 2.95 Å. Ir is bonded in a body-centered cubic geometry to four equivalent Tm and four equivalent Dy atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on DyHoTl2 by Materials Project

HoDyTl2 is Heusler structured and crystallizes in the cubic Fm-3m space group. The structure is three-dimensional. Ho is bonded in a body-centered cubic geometry to eight equivalent Tl atoms. All Ho–Tl bond lengths are 3.28 Å. Dy is bonded in a body-centered cubic geometry to eight equivalent Tl atoms. All Dy–Tl bond lengths are 3.28 Å. Tl is bonded in a body-centered cubic geometry to four equivalent Ho and four equivalent Dy atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on DyLuTl2 by Materials Project

LuDyTl2 is Heusler structured and crystallizes in the cubic Fm-3m space group. The structure is three-dimensional. Lu is bonded in a body-centered cubic geometry to eight equivalent Tl atoms. All Lu–Tl bond lengths are 3.26 Å. Dy is bonded in a body-centered cubic geometry to eight equivalent Tl atoms. All Dy–Tl bond lengths are 3.26 Å. Tl is bonded in a body-centered cubic geometry to four equivalent Lu and four equivalent Dy atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on DyHo3 by Materials Project

Ho3Dy is Magnesium-derived structured and crystallizes in the hexagonal P6_3/mmc space group. The structure is three-dimensional. Ho is bonded to eight equivalent Ho and four equivalent Dy atoms to form HoDy4Ho8 cuboctahedra that share corners with four equivalent DyHo12 cuboctahedra, corners with fourteen equivalent HoDy4Ho8 cuboctahedra, edges with six equivalent DyHo12 cuboctahedra, edges with twelve equivalent HoDy4Ho8 cuboctahedra, faces with four equivalent DyHo12 cuboctahedra, and faces with sixteen equivalent HoDy4Ho8 cuboctahedra. There are a spread of Ho–Ho bond distances ranging from 3.50–3.60 Å. There are two shorter (3.51 Å) and two longer (3.60 Å) Ho–Dy bond lengths. Dy is bonded to twelve equivalent Ho atoms to form DyHo12 cuboctahedra that share corners with six equivalent DyHo12 cuboctahedra, corners with twelve equivalent HoDy4Ho8 cuboctahedra, edges with eighteen equivalent HoDy4Ho8 cuboctahedra, faces with eight equivalent DyHo12 cuboctahedra, and faces with twelve equivalent HoDy4Ho8 cuboctahedra.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on La5Dy3(CuO4)4 by Materials Project

Dy3La5(CuO4)4 crystallizes in the tetragonal P4mm space group. The structure is three-dimensional. there are three inequivalent Dy3+ sites. In the first Dy3+ site, Dy3+ is bonded in a distorted body-centered cubic geometry to eight O2- atoms. There are four shorter (2.25 Å) and four longer (2.65 Å) Dy–O bond lengths. In the second Dy3+ site, Dy3+ is bonded in a distorted body-centered cubic geometry to eight O2- atoms. There are four shorter (2.25 Å) and four longer (2.65 Å) Dy–O bond lengths. In the third Dy3+ site, Dy3+ is bonded in a distorted body-centered cubic geometry to eight O2- atoms. There are four shorter (2.24 Å) and four longer (2.63 Å) Dy–O bond lengths. There are five inequivalent La3+ sites. In the first La3+ site, La3+ is bonded in a 1-coordinate geometry to nine O2- atoms. There are a spread of La–O bond distances ranging from 2.30–2.80 Å. In the second La3+ site, La3+ is bonded in a 1-coordinate geometry to nine O2- atoms. There are a spread of La–O bond distances ranging from 2.30–2.80 Å. In the third La3+ site, La3+ is bonded in a 1-coordinate geometry to nine O2- atoms. There are a spread of La–O bond distances ranging from 2.29–2.80 Å. In the fourth La3+ site, La3+ is bonded in a 1-coordinate geometry to nine O2- atoms. There are a spread of La–O bond distances ranging from 2.30–2.80 Å. In the fifth La3+ site, La3+ is bonded in a distorted body-centered cubic geometry to eight O2- atoms. There are four shorter (2.34 Å) and four longer (2.72 Å) La–O bond lengths. There are four inequivalent Cu2+ sites. In the first Cu2+ site, Cu2+ is bonded to five O2- atoms to form corner-sharing CuO5 square pyramids. There are four shorter (1.93 Å) and one longer (2.33 Å) Cu–O bond lengths. In the second Cu2+ site, Cu2+ is bonded to five O2- atoms to form corner-sharing CuO5 square pyramids. There are four shorter (1.93 Å) and one longer (2.38 Å) Cu–O bond lengths. In the third Cu2+ site, Cu2+ is bonded to five O2- atoms to form corner-sharing CuO5 square pyramids. There are four shorter (1.93 Å) and one longer (2.37 Å) Cu–O bond lengths. In the fourth Cu2+ site, Cu2+ is bonded to five O2- atoms to form corner-sharing CuO5 square pyramids. There are four shorter (1.93 Å) and one longer (2.39 Å) Cu–O bond lengths. There are ten inequivalent O2- sites. In the first O2- site, O2- is bonded in a 6-coordinate geometry to five La3+ and one Cu2+ atom. In the second O2- site, O2- is bonded in a 6-coordinate geometry to five La3+ and one Cu2+ atom. In the third O2- site, O2- is bonded in a 6-coordinate geometry to five La3+ and one Cu2+ atom. In the fourth O2- site, O2- is bonded in a 6-coordinate geometry to five La3+ and one Cu2+ atom. In the fifth O2- site, O2- is bonded to two equivalent Dy3+ and two equivalent La3+ atoms to form OLa2Dy2 tetrahedra that share corners with twelve OLa4Cu2 octahedra, corners with four equivalent OLa2Dy2 tetrahedra, edges with two OLa4Cu2 octahedra, and edges with four equivalent OLa2Dy2 tetrahedra. The corner-sharing octahedra tilt angles range from 10–70°. In the sixth O2- site, O2- is bonded to four Dy3+ atoms to form ODy4 tetrahedra that share corners with twelve OLa2Dy2Cu2 octahedra, corners with four equivalent ODy4 tetrahedra, edges with two OLa2Dy2Cu2 octahedra, and edges with four equivalent ODy4 tetrahedra. The corner-sharing octahedra tilt angles range from 12–69°. In the seventh O2- site, O2- is bonded to four La3+ and two equivalent Cu2+ atoms to form distorted OLa4Cu2 octahedra that share corners with two equivalent OLa4Cu2 octahedra, corners with six equivalent OLa2Dy2 tetrahedra, edges with two equivalent OLa4Cu2 octahedra, an edgeedge with one OLa2Dy2 tetrahedra, and faces with four equivalent OLa4Cu2 octahedra. The corner-sharing octahedral tilt angles are 1°. In the eighth O2- site, O2- is bonded to two equivalent Dy3+, two equivalent La3+, and two equivalent Cu2+ atoms to form distorted OLa2Dy2Cu2 octahedra that share corners with two equivalent OLa2Dy2Cu2 octahedra, corners with six equivalent ODy4 tetrahedra, edges with two equivalent OLa2Dy2Cu2 octahedra, an edgeedge with one ODy4 tetrahedra, and faces with four equivalent OLa2Dy2Cu2 octahedra. The corner-sharing octahedral tilt angles are 1°. In the ninth O2- site, O2- is bonded to two equivalent Dy3+, two equivalent La3+, and two equivalent Cu2+ atoms to form distorted OLa2Dy2Cu2 octahedra that share corners with two equivalent OLa2Dy2Cu2 octahedra, corners with six equivalent ODy4 tetrahedra, edges with two equivalent OLa2Dy2Cu2 octahedra, an edgeedge with one ODy4 tetrahedra, and faces with four equivalent OLa2Dy2Cu2 octahedra. The corner-sharing octahedral tilt angles are 1°. In the tenth O2- site, O2- is bonded to two equivalent Dy3+, two equivalent La3+, and two equivalent Cu2+ atoms to form distorted OLa2Dy2Cu2 octahedra that share corners with two equivalent OLa2Dy2Cu2 octahedra, corners with six equivalent OLa2Dy2 tetrahedra, edges with two equivalent OLa2Dy2Cu2 octahedra, an edgeedge with one OLa2Dy2 tetrahedra, and faces with four equivalent OLa2Dy2Cu2 octahedra. The corner-sharing octahedral tilt angles are 0°.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Dy11(Mn2C3)6 by Materials Project

Dy(Dy5(Mn2C3)3)2 crystallizes in the cubic I-43m space group. The structure is three-dimensional and consists of two dysprosium molecules and one Dy5(Mn2C3)3 framework. In the Dy5(Mn2C3)3 framework, there are two inequivalent Dy3+ sites. In the first Dy3+ site, Dy3+ is bonded to six equivalent C+3.17- atoms to form distorted DyC6 pentagonal pyramids that share corners with six equivalent DyC6 pentagonal pyramids and edges with six equivalent DyC8 hexagonal bipyramids. There are three shorter (2.59 Å) and three longer (2.66 Å) Dy–C bond lengths. In the second Dy3+ site, Dy3+ is bonded to eight C+3.17- atoms to form distorted DyC8 hexagonal bipyramids that share edges with two equivalent DyC8 hexagonal bipyramids, edges with four equivalent DyC6 pentagonal pyramids, and faces with four equivalent DyC8 hexagonal bipyramids. There are four shorter (2.50 Å) and four longer (2.63 Å) Dy–C bond lengths. Mn2+ is bonded in a distorted trigonal non-coplanar geometry to three C+3.17- atoms. There is two shorter (1.87 Å) and one longer (2.06 Å) Mn–C bond length. There are two inequivalent C+3.17- sites. In the first C+3.17- site, C+3.17- is bonded in a 7-coordinate geometry to four equivalent Dy3+, two equivalent Mn2+, and one C+3.17- atom. The C–C bond length is 1.38 Å. In the second C+3.17- site, C+3.17- is bonded to four Dy3+ and two equivalent Mn2+ atoms to form a mixture of distorted corner and edge-sharing CDy4Mn2 octahedra. The corner-sharing octahedra tilt angles range from 3–70°.

36 MATERIALS SCIENCE↗
DOE OSTI2020

The magnetic order in multiferroic DyMnO 3

We report that with flexibility in tuning their electric and magnetic properties, multiferroics can be used in information exchange and storage in ways that are very different from the present electronic materials. Here we use resonant soft X-ray scattering spectroscopy to study the F-type (0,τ,0) and C-type (0, 1–2τ, 0) diffraction peaks from sinusoidal antiferromagnetic spin order in multiferroic DyMnO 3 . By comparing the temperature dependence of ordering wave vectors τ, peak intensities I, and correlation lengths λ measured at Mn L 2 - , O K-, and Dy M 5 -edges, we show that the nearly perfect locking between the ordering wave vectors from Dy 4f states and Mn 3d orbitals manifesting the second harmonic diffraction peak implies the notable orbital involvement in the coupling between Mn and Dy spins. Our DFT calculations further suggest that the lattice response to different antiferromagnetic ground states (A-type versus E-type) is much weaker in TbMnO 3 , in agreement with previous claim that the symmetric exchange interaction can be an important factor for understanding the ferroelectricity in DyMnO 3 than in TbMnO 3 .

36 MATERIALS SCIENCE↗
DOE OSTI2022

Nuclear Structure and Decay Data for A=149 Isobars

Here, experimental nuclear structure and decay data are evaluated for all the 17 known nuclides of mass 149 (Xe, Cs, Ba, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb). Detailed compiled and evaluated spectroscopic information is presented for each reaction and decay dataset, and recommended values are provided for level properties, α, β and γ radiations, and other spectroscopic parameters, based on an evaluation of all the available experimental data for A=149 isobaric nuclides. Although large amounts of nuclear spectroscopic data are available for nuclides of A=149, yet large gaps in knowledge exist, as described below. For the lowest atomic number nuclide 149 Xe, only the isotopic identification has been made, with no data for its ground-state half-life. For 149 Cs, 149 Tm and 149 Yb information is available for only the respective ground states. For 149 Ba, 149 La and 149 Er, limited data exist for excited states. Many of the decay schemes of radioactive nuclei of A=149 are considered as incomplete, either due to large energy differences between the highest observed excited states in daughter nuclides and the respective Q-values, or due to the lack of confirmed γ-ray data, as listed below: 149 Cs → 149 Ba, 149 Ba → 149 La, 149 La → 149 Ce, 149 Ce → 149 Pr, 149 Pr → 149 Nd, 149 Tb(4.17 min) → 149 Gd, 149 Ho(21.0 s and 56 s) → 149 Dy, 149 Er(4 s and 9.6 s) → 149 Ho, and 149 Tm → 149 Er. No data exist for the decay of 149 Yb to 149 Tm. Data for half-lives of the excited states in this mass chain are generally lacking as given below by the number of excited levels of known half-life / approximate number of known levels in a nuclide: 2/17 for 149 Ba, 0/18 for 149 La, 3/53 for 149 Ce, 3/44 for 149 Pr, 17/110 for 149 Nd, 9/90 for 149 Pm, 10/210 for 149 Sm, 2/125 for 149 Eu, 6/270 for 149 Gd, 5/200 for 149 Tb, 3/80 for 149 Dy, 3/90 for 149 Ho, and 3/14 for 149 Er. This work supersedes earlier evaluations of A=149 nuclides published by 2004Si16, 1994Si18, 1985Sz01 and 1976Ho17.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2025

Influence of Compositional Complexity on Amorphization Resistance of Swift Heavy Ion Irradiated Titanate Pyrochlores

Compositionally complex oxides have garnered attention recently for their potential technological applications in harsh environments such as thermal barrier coatings and nuclear waste forms. Therefore, their response to extreme conditions, including high temperature and intense irradiation fields, must be thoroughly investigated. Here, the structural evolution of two pyrochlore oxides with comparable cation size ratio, r A /r B , (Yb 0.2 Er 0.2 Dy 0.2 Tb 0.2 Gd 0.2 ) 2 Ti 2 O 7 and Ho 2 Ti 2 O 7 , was evaluated after irradiation with 946 MeV Au ions up to a fluence of 8 × 10 12 ions/cm2 using synchrotron X-ray diffraction, transmission electron microscopy, and Raman spectroscopy. The overall radiation response is comparable for both titanate oxides and is dominated by a loss of crystallinity. When compared to a series of conventional titanate pyrochlore compositions, the amorphous track diameter of (Yb 0.2 Er 0.2 Dy 0.2 Tb 0.2 Gd 0.2 ) 2 Ti 2 O 7 is slightly larger than that of Ho2Ti2O7 and more in line with the diameter of the endmember with the maximum A-site cation size (Gd 2 Ti 2 O 7 ). Density functional theory calculations suggest that this behavior may be linked to local lattice distortions and the associated energetics of cation antisite formation. TEM and Raman analyses show that a disordered, crystalline shell surrounds the amorphous ion tracks in (Yb 0.2 Er 0.2 Dy 0.2 Tb 0.2 Gd 0.2 ) 2 Ti 2 O 7 , and the corresponding short-range structure resembles a weberite-type atomic arrangement.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2023

Strong Axiality in a Dysprosium(III) Bis(borolide) Complex Leads to Magnetic Blocking at 65 K

Substituted dysprosocenium complexes of the type [Dy(Cp R ) 2 ] + exhibit slow magnetic relaxation at cryogenic temperatures and have emerged as top-performing single-molecule magnets. The remarkable properties of these compounds derive in part from the strong axial ligand field afforded by the cyclopentadiene anions, and the design of analogous compounds with even stronger ligand fields is one promising route toward identifying new single-molecule magnets that retain a magnetic memory at even higher temperatures. Here, we report the synthesis and characterization of a dysprosium bis(borolide) compound, [K(18-crown-6)][Dy(BC 4 Ph 5 ) 2 ] (1), featuring the dysprosocenate anion [Dy(BC 4 Ph 5 ) 2 ] - with a pseudoaxial coordination environment afforded by two dianionic pentaphenyl borolide ligands. Variable-field magnetization data reveal open magnetic hysteresis up to 66 K, establishing 1 as a top-performing single-molecule magnet among its dysprosocenium analogues. Ac magnetic susceptibility data indicate that 1 relaxes via an Orbach mechanism above ~80 K with U eff = 1500(100) cm -1 and τ 0 = 10 -12.0(9) s, whereas Raman relaxation and quantum tunneling of the magnetization dominate at lower temperatures. Compound 1 exhibits a 100 s blocking temperature of 65 K, among the highest reported for dysprosium-based single-molecule magnets. Ab initio spin dynamics calculations support the experimental U eff and τ 0 values and enable a quantitative comparison of the relaxation dynamics of 1 and two representative dysprosocenium cations, yielding additional insights into the impact of the crystal field splitting and vibronic coupling on the observed relaxation behavior. Importantly, compound 1 represents a step toward the development of alternatives to substituted dysprosocenium single-molecule magnets with increased axiality.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2024

Coercive Fields Exceeding 30 T in the Mixed-Valence Single-Molecule Magnet (Cp iPr5 ) 2 Ho 2 I 3

Mixed-valence dilanthanide complexes of the type (Cp iPr5 ) 2 Ln 2 I 3 (Cp iPr5 = pentaisopropylcyclopentadienyl; Ln = Gd, Tb, Dy) featuring a direct Ln–Ln σ-bonding interaction have been shown to exhibit well-isolated high-spin ground states and, in the case of the Tb and Dy variants, a strong axial magnetic anisotropy that gives rise to a large magnetic coercivity. Here, we report the synthesis and characterization of two new mixed-valence dilanthanide compounds in this series, (Cp iPr5 ) 2 Ln 2 I 3 (1-Ln; Ln = Ho, Er). Both compounds feature a Ln–Ln bonding interaction, the first such interaction in any molecular compounds of Ho or Er. Like the Tb and Dy congeners, both complexes exhibit high-spin ground states arising from strong spin–spin coupling between the lanthanide 4f electrons and a single σ-type lanthanide–lanthanide bonding electron. Beyond these similarities, however, the magnetic properties of the two compounds diverge. In particular, 1-Er does not exhibit observable magnetic blocking or slow magnetic relaxation, while 1-Ho exhibits magnetic blocking below 28 K, which is the highest temperature among Ho-based single-molecule magnets, and a spin reversal barrier of 556(4) cm –1 . Additionally, variable-field magnetization data collected for 1-Ho reveal a coercive field of greater than 32 T below 8 K, more than 6-fold higher than observed for the bulk magnets SmCo 5 and Nd 2 Fe 14 B, and the highest coercive field reported to date for any single-molecule magnet or molecule-based magnetic material. Multiconfigurational calculations, supported by far-infrared magnetospectroscopy data, reveal that the stark differences in magnetic properties of 1-Ho and 1-Er arise from differences in the local magnetic anisotropy of the lanthanide centers.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2021

Comparison of short-range order in irradiated dysprosium titanates

Abstract The structural response of Dy 2 TiO 5 oxide under swift heavy ion irradiation (2.2 GeV Au ions) was studied over a range of structural length scales utilizing neutron total scattering experiments. Refinement of diffraction data confirms that the long-range orthorhombic structure is susceptible to ion beam-induced amorphization with limited crystalline fraction remaining after irradiation to 8 × 10 12 ions/cm 2 . In contrast, the local atomic arrangement, examined through pair distribution function analysis, shows only subtle changes after irradiation and is still described best by the original orthorhombic structural model. A comparison to Dy 2 Ti 2 O 7 pyrochlore oxide under the same irradiation conditions reveals a different behavior: while the dysprosium titanate pyrochlore is more radiation resistant over the long-range with smaller degree of amorphization as compared to Dy 2 TiO 5 , the former involves more local atomic rearrangements, best described by a pyrochlore-to-weberite-type transformation. These results highlight the importance of short-range and medium-range order analysis for a comprehensive description of radiation behavior.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2025

Structural incorporation into goethite fractionates rare earth elements

Up to 20% of rare earth elements (REEs) in ion adsorption deposits (IADs) are associated with iron oxide minerals, primarily goethite. Often termed “non-extractable”, goethite-hosted REEs are thought to be structurally incorporated into the mineral lattice. The large mismatch in size and charge density between REEs (ionic radius, r = 0.86–1.03 Å) and Fe 3+ (r = 0.65 Å), however, makes direct substitution energetically unfavorable. To determine REE compatibility with and incorporation into goethite on the atomic level, we used X-ray pair distribution function analysis (PDF) and LIII-edge extended X-ray absorption fine structure (EXAFS) spectroscopy. The compatibility of REEs with goethite and the precursor ferrihydrite (FH) is Lu ≥ Yb ≫ Dy > Nd for both phases. Nd and Dy primarily form secondary amorphous phases, with <30% Nd and Dy incorporated into goethite. In the FH precursor at pH 6.8, Yb and Lu assumed a local REE-OOH like structure with next nearest neighbor Fe. The Yb, Lu, and Nd-FH samples were also matured at ambient conditions for 100 days; despite the presence of only ∼5% goethite, Lu and Yb were 42% and 100% in goethite-like structural environments, respectively, whereas the PDF and EXAFS of Nd showed little evidence of any incorporation. Using ab initio molecular dynamics (AIMD) to model the EXAFS, we determined the presence of protonated Fe vacancies, edge-sharing with structural Lu and Yb, likely helped accommodate these REEs in the goethite structure. Incorporation into Fe oxyhydroxides thus potentially fractionates the REEs during weathering associated with formation of lateritic and ion adsorption deposits.

Mergelsberg, Sebastian T. [Pacific Northwest Natio↗
DOE OSTI2021

Rare-earth orbital moment contributions to the magnetic anisotropy in magnetostrictive Tb0.3Dy0.7Fe2

Soft x-ray Magnetic Circular Dichroism spectroscopy at the Dy and Tb M4,5 and the Fe L2,3 edges was performed on a sputter deposited polycrystalline Terfenol-D (Tb0.3Dy0.7Fe2) film on sapphire substrates at temperatures from 100 to 300 K to evaluate the elementwise contribution to the magnetocrystalline anisotropy and coercive field. The elemental spin and orbital magnetic moments were calculated using the x-ray Magnetic Circular Dichroism sum rules. As temperatures decreased, the Tb and Fe moments plateau at 200 K with values of 7.6 μB/atom and 1.8 μB/atom, respectively, while the Dy moment increases to 8.9 μB/atom at 100 K. Between 300 and 200 K, the change in magnetic anisotropy is dominated by thermally induced magnetoelastic effects while for temperatures below 200 K magnetocrystalline anisotropy (MCA) changes are dominant. The MCA changes below 200 K appear to be due to increases in the Dy orbital moment with decreasing temperature in this temperature regime.

Shirazi, Paymon (ORCID:0000000256954597)↗