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At least 19 records
All sourcesNASA NTRSDOE OSTI
DOE OSTI2025

Exploring Anomalous Photoelectron Angular Distributions in the Photoelectron Spectra of Gd 3 O 3 – : Study of Gd 3 O 2 – and Gd 3 O 3 – Using Photoelectron Spectroscopy and Density Functional Theory Calculations

Anion photoelectron (PE) spectra of lanthanide oxide clusters obtained previously have exhibited anomalous photoelectron angular distributions which were attributed to strong PE–valence electron (PEVE) interactions. Here, to further explore this effect, we have obtained the PE spectra of Gd 3 O 2 – and Gd 3 O 3 – , two clusters that have similarly complex electronic structures but contrasting symmetries. The spectra exhibit manifolds of detachment transitions at similar binding energies in a 0.5 eV window of energy. The electron affinity of Gd 3 O 2 is measured to be 1.29 ± 0.05 eV, and that of Gd 3 O 3 is 1.31 ± 0.05 eV. As seen in previous studies on lanthanide oxide cluster anions in lower than conventional oxidation states, transitions in spectra obtained lower photon energies are more congested than those obtained with higher photon energy, a signature of strong PEVE interactions. While the detachment transitions have predominantly parallel photoelectron angular distributions (PAD), the PAD varies across the manifold of transitions in the PE spectrum of Gd 3 O 3 – in a way that suggests four different subgroups of transitions. Results of calculations on Gd 3 O 2 – suggest kite or V-shape structures with antiferromagnetic coupling between one of the 4f 7 subshells with the two others. Calculations on Gd 3 O 3 – more definitively point to ring structures with a nearly isoenergetic ferromagnetically coupled high spin (24-tet) state and a dectet state in which one of the 4f 7 subshells is antiferromagnetically coupled with the other two. Taking these results as qualitative, we propose that strong mixing between the unperturbed states predicted computationally leads to overlapping transitions with different PADs.

anions↗
DOE OSTI2025

Benchmark results with a new evaluation of 155 Gd and 157 Gd

Evaluations of gadolinium isotopes 155 Gd and 157 Gd in the resolved resonance region were performed with the code SAMMY. The main objective for revising the resonance evaluations of these isotopes was to address issues related to critical benchmark results.

07 ISOTOPE AND RADIATION SOURCES↗
DOE OSTI2020

Materials Data on Gd by Materials Project

Gd is alpha Samarium structured and crystallizes in the trigonal R-3m space group. The structure is three-dimensional. there are four inequivalent Gd sites. In the first Gd site, Gd is bonded to twelve Gd atoms to form a mixture of face, edge, and corner-sharing GdGd12 cuboctahedra. There are six shorter (3.57 Å) and six longer (3.62 Å) Gd–Gd bond lengths. In the second Gd site, Gd is bonded to twelve Gd atoms to form a mixture of face, edge, and corner-sharing GdGd12 cuboctahedra. There are three shorter (3.57 Å) and six longer (3.62 Å) Gd–Gd bond lengths. In the third Gd site, Gd is bonded to twelve Gd atoms to form a mixture of face, edge, and corner-sharing GdGd12 cuboctahedra. There are six shorter (3.57 Å) and six longer (3.62 Å) Gd–Gd bond lengths. In the fourth Gd site, Gd is bonded to twelve Gd atoms to form a mixture of face, edge, and corner-sharing GdGd12 cuboctahedra. There are six shorter (3.57 Å) and six longer (3.62 Å) Gd–Gd bond lengths.

36 MATERIALS SCIENCE↗
DOE OSTI2021

Thermodynamic properties of Gd-Bi alloys determined by emf measurements in LiCl-KCl-GdCl 3 electrolyte

Thermodynamic properties of binary Gd-Bi alloys (mole fraction, x Gd = 0.02–0.35) were determined using electromotive force (emf) measurements in molten LiCl-KCl-GdCl 3 electrolyte in complement with structural, microstructural, and thermal characterization. X-ray diffractometry (XRD) and scanning electron microscopy (SEM) identified the phase constituents of Gd-Bi alloys (x Gd = 0.02–0.35) as Bi matrix and GdBi compound. According to differential scanning calorimetry (DSC) measurements up to 1250 K, a eutectic transition [L = Bi + GdBi] was observed at 543 K but the reported peritectic transition [L + GdBi = GdBi 2 ] was not detected, suggesting the absence of the GdBi 2 compound. Based on structural, microstructural, and thermal characterization of Gd-Bi alloys (x Gd = 0.02–0.35), the GdBi 2 compound was not detected, and its thermodynamic stability is questionable. The emf of Gd-Bi alloy (x Gd = 0.16) at 700–1048 K relative to Gd(s) was measured by electrodepositing pure Gd metal at 25 K increments. Further, the emf values of Gd-Bi alloys were determined via coulometric titration of Gd into liquid Bi using a two-phase [L + GdBi] alloy as a reference electrode at 773–973 K. The solubility of Gd in liquid Bi was also estimated to be 0.50 mol% (773 K), 0.99 mol% (873 K), and 2.21 mol% (973 K) and the excess partial molar Gibbs energy (Δ$\mathrm{\bar{G}^{ex}_{Gd}}$) of liquid Gd-Bi alloys was as low as 65 kJ mol –1 , indicating strong chemical interactions between Gd and Bi.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Gd by Materials Project

Gd is alpha La structured and crystallizes in the hexagonal P6_3/mmc space group. The structure is three-dimensional. there are two inequivalent Gd sites. In the first Gd site, Gd is bonded to twelve Gd atoms to form a mixture of corner, edge, and face-sharing GdGd12 cuboctahedra. There are six shorter (3.58 Å) and six longer (3.61 Å) Gd–Gd bond lengths. In the second Gd site, Gd is bonded to twelve Gd atoms to form a mixture of corner, edge, and face-sharing GdGd12 cuboctahedra. All Gd–Gd bond lengths are 3.61 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Gd(Mg4Al3)4 by Materials Project

Gd(Mg4Al3)4 is gamma-brass-derived structured and crystallizes in the trigonal R3m space group. The structure is three-dimensional. there are five inequivalent Mg sites. In the first Mg site, Mg is bonded in a 11-coordinate geometry to five Mg and six Al atoms. There are a spread of Mg–Mg bond distances ranging from 3.05–3.35 Å. There are a spread of Mg–Al bond distances ranging from 3.05–3.12 Å. In the second Mg site, Mg is bonded in a 9-coordinate geometry to three equivalent Mg, one Gd, and twelve Al atoms. The Mg–Gd bond length is 3.33 Å. There are a spread of Mg–Al bond distances ranging from 3.13–3.23 Å. In the third Mg site, Mg is bonded in a 3-coordinate geometry to seven Mg, one Gd, and five Al atoms. There are a spread of Mg–Mg bond distances ranging from 3.16–3.28 Å. The Mg–Gd bond length is 3.57 Å. There are a spread of Mg–Al bond distances ranging from 2.87–3.24 Å. In the fourth Mg site, Mg is bonded in a 6-coordinate geometry to seven Mg, one Gd, and five Al atoms. There are two shorter (3.11 Å) and two longer (3.15 Å) Mg–Mg bond lengths. The Mg–Gd bond length is 3.10 Å. There are a spread of Mg–Al bond distances ranging from 2.83–3.16 Å. In the fifth Mg site, Mg is bonded in a 12-coordinate geometry to seven Mg and five Al atoms. Both Mg–Mg bond lengths are 3.04 Å. There are a spread of Mg–Al bond distances ranging from 2.96–3.32 Å. Gd is bonded in a 12-coordinate geometry to seven Mg and nine Al atoms. There are three shorter (3.19 Å) and six longer (3.22 Å) Gd–Al bond lengths. There are three inequivalent Al sites. In the first Al site, Al is bonded in a 12-coordinate geometry to eight Mg, one Gd, and three Al atoms. There are one shorter (2.66 Å) and two longer (2.74 Å) Al–Al bond lengths. In the second Al site, Al is bonded in a 11-coordinate geometry to eight Mg and three Al atoms. Both Al–Al bond lengths are 2.73 Å. In the third Al site, Al is bonded in a 11-coordinate geometry to seven Mg, one Gd, and three Al atoms. There are one shorter (2.72 Å) and one longer (2.76 Å) Al–Al bond lengths.

36 MATERIALS SCIENCE↗
DOE OSTI2023

Electrochemical properties of Gd(III) ions in LiCl-KCl-GdCl 3 at 723–1023 K

Electrochemical behavior of Gd(III) ions in molten LiCl-KCl-GdCl 3 was investigated at 723–1023 K via cyclic voltammetry using tungsten as a working electrode, Gd-Bi (mole fraction, x Gd = 0.16) as a reference electrode, and Gd-Bi (x Gd = 0.02) as a counter electrode. A single reduction–oxidation wave was observed, confirming a single-step, 3-electron transfer Gd(III)/Gd transition. The cathodic peak potential exhibited minimal change (<13 mV) over a wide range of scan rates (0.05–0.30 V s –1 ), indicating facile charge transfer kinetics (i.e., a reversible electrode process). A nucleation overpotential associated with solid Gd deposition was observable at low temperatures (T < 823 K). The mass transport properties of Gd(III) ions were estimated using the Berzins and Delahay relation based on diffusion-limiting peak current. The diffusivity values were determined to be D Gd(III) = 0.5–2.7 × 10 –5 cm 2 s –1 at 723–1023 K with an associated activation energy of E a = 33.9 (±1.0) kJ mol –1 . Finally, the two-phase [liquid + GdBi] Gd-Bi alloy reference electrode experienced less than 0.5 mV of drift over 5 days of repeated electrochemical measurements, indicating high stability.

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

Crystal structure and magnetic properties of Gd 8 Mn 3 Sb 19

Here, in this study, a novel magnetic semimetal compound, Gd 8 Mn 3 Sb 19 , was synthesized successfully via high-temperature solid-state reaction. The crystal structure of Gd 8 Mn 3 Sb 19 was determined using both single crystal and powder X-ray diffraction techniques, revealing a non-centrosymmetric orthorhombic space group, Pmn2 1 (No. 31). The Sb atoms in Gd 8 Mn 3 Sb 19 form five-atom-wide Sb 5 7− ribbons, narrower three-atom-wide Sb 3 5− ribbons, and single Sb 3− anions. On the other hand, both Gd 3+ and Mn 2+ ions form the distorted Gd 3 and Mn 3 triangular lattices, respectively. The magnetic measurements suggest the complex magnetic interactions contributed by both Gd 3+ and Mn 2+ ions. A sharp peak observed in the magnetic susceptibility plot at approximately 25 K corresponds to the antiferromagnetic-type transition in Gd 8 Mn 3 Sb 19 . Furthermore, the magnetic measurements along different directions indicate the strong magnetic anisotropy present in Gd 8 Mn 3 Sb 19 , which is likely due to the complex magnetic interactions arising from the existence of Gd and Mn ions. Finally, the electrical resistivity measurements of Gd 8 Mn 3 Sb 19 indicate semimetallic behavior with a positive magnetoresistance.

Chemistry↗
DOE OSTI2020

Materials Data on Gd(Fe5Si)2 by Materials Project

Gd(Fe5Si)2 crystallizes in the orthorhombic Immm space group. The structure is three-dimensional. Gd is bonded in a 12-coordinate geometry to sixteen Fe and four equivalent Si atoms. There are a spread of Gd–Fe bond distances ranging from 2.95–3.18 Å. All Gd–Si bond lengths are 3.09 Å. There are four inequivalent Fe sites. In the first Fe site, Fe is bonded in a 10-coordinate geometry to one Gd, eleven Fe, and two equivalent Si atoms. There are a spread of Fe–Fe bond distances ranging from 2.32–2.90 Å. Both Fe–Si bond lengths are 2.59 Å. In the second Fe site, Fe is bonded in a 10-coordinate geometry to one Gd, eleven Fe, and two equivalent Si atoms. There are a spread of Fe–Fe bond distances ranging from 2.41–2.65 Å. Both Fe–Si bond lengths are 2.51 Å. In the third Fe site, Fe is bonded in a 12-coordinate geometry to two equivalent Gd, eight Fe, and two equivalent Si atoms. All Fe–Fe bond lengths are 2.43 Å. Both Fe–Si bond lengths are 2.65 Å. In the fourth Fe site, Fe is bonded to two equivalent Gd, eight Fe, and two equivalent Si atoms to form distorted FeGd2Fe8Si2 cuboctahedra that share corners with four equivalent SiGd2Fe10 cuboctahedra, corners with ten equivalent FeGd2Fe8Si2 cuboctahedra, edges with two equivalent SiGd2Fe10 cuboctahedra, edges with four equivalent FeGd2Fe8Si2 cuboctahedra, faces with four equivalent SiGd2Fe10 cuboctahedra, and faces with six equivalent FeGd2Fe8Si2 cuboctahedra. Both Fe–Fe bond lengths are 2.37 Å. Both Fe–Si bond lengths are 2.39 Å. Si is bonded to two equivalent Gd and ten Fe atoms to form distorted SiGd2Fe10 cuboctahedra that share corners with six equivalent SiGd2Fe10 cuboctahedra, corners with eight equivalent FeGd2Fe8Si2 cuboctahedra, edges with three equivalent SiGd2Fe10 cuboctahedra, edges with four equivalent FeGd2Fe8Si2 cuboctahedra, a faceface with one SiGd2Fe10 cuboctahedra, and faces with eight equivalent FeGd2Fe8Si2 cuboctahedra.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Gd(AlCr)6 by Materials Project

Gd(CrAl)6 crystallizes in the orthorhombic Immm space group. The structure is three-dimensional. Gd is bonded in a 8-coordinate geometry to twelve Cr and eight Al atoms. There are four shorter (3.37 Å) and eight longer (3.40 Å) Gd–Cr bond lengths. There are a spread of Gd–Al bond distances ranging from 3.00–3.11 Å. There are two inequivalent Cr sites. In the first Cr site, Cr is bonded to two equivalent Gd, four Cr, and six Al atoms to form a mixture of distorted edge, face, and corner-sharing CrGd2Al6Cr4 cuboctahedra. There are two shorter (2.56 Å) and two longer (2.58 Å) Cr–Cr bond lengths. There are a spread of Cr–Al bond distances ranging from 2.63–2.72 Å. In the second Cr site, Cr is bonded to two equivalent Gd, four equivalent Cr, and six Al atoms to form a mixture of distorted edge, face, and corner-sharing CrGd2Al6Cr4 cuboctahedra. There are a spread of Cr–Al bond distances ranging from 2.68–2.78 Å. There are three inequivalent Al sites. In the first Al site, Al is bonded in a 10-coordinate geometry to one Gd, six Cr, and three Al atoms. There are one shorter (2.72 Å) and two longer (2.89 Å) Al–Al bond lengths. In the second Al site, Al is bonded in a 7-coordinate geometry to one Gd, six Cr, and two equivalent Al atoms. Both Al–Al bond lengths are 3.06 Å. In the third Al site, Al is bonded in a 12-coordinate geometry to two equivalent Gd, six Cr, and four Al atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Gd(Al3Ni)3 by Materials Project

GdNi3Al9 crystallizes in the trigonal R32 space group. The structure is three-dimensional. Gd is bonded in a 11-coordinate geometry to six equivalent Ni and eleven Al atoms. There are three shorter (3.29 Å) and three longer (3.30 Å) Gd–Ni bond lengths. There are a spread of Gd–Al bond distances ranging from 3.00–3.17 Å. Ni is bonded in a 8-coordinate geometry to two equivalent Gd and eight Al atoms. There are a spread of Ni–Al bond distances ranging from 2.33–2.63 Å. There are six inequivalent Al sites. In the first Al site, Al is bonded in a distorted trigonal non-coplanar geometry to one Gd, three equivalent Ni, and seven Al atoms. There are a spread of Al–Al bond distances ranging from 2.77–2.84 Å. In the second Al site, Al is bonded in a 2-coordinate geometry to two equivalent Gd, two equivalent Ni, and six Al atoms. There are two shorter (2.63 Å) and four longer (2.81 Å) Al–Al bond lengths. In the third Al site, Al is bonded in a linear geometry to two equivalent Ni and six Al atoms. There are two shorter (2.81 Å) and two longer (2.84 Å) Al–Al bond lengths. In the fourth Al site, Al is bonded in a 3-coordinate geometry to two equivalent Gd, three equivalent Ni, and five Al atoms. There are one shorter (2.71 Å) and one longer (2.78 Å) Al–Al bond lengths. In the fifth Al site, Al is bonded in a distorted trigonal non-coplanar geometry to three equivalent Ni and seven Al atoms. The Al–Al bond length is 2.87 Å. In the sixth Al site, Al is bonded in a distorted trigonal non-coplanar geometry to one Gd, three equivalent Ni, and seven Al atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2025

Electrochemical recovery of Gd into liquid Bi in molten LiCl-KCl-GdCl 3

The electrochemical recovery of Gd into liquid Bi electrodes was investigated in molten LiCl-KCl-GdCl 3 electrolyte at 773–973 K using constant currents of 10–150 mA cm −2 . High round-trip coulombic efficiency (>97 %) was demonstrated for deposition and removal of Gd into and from liquid Bi at all temperatures, confirming chemically reversible electrode reactions towards high recovery yield of Gd using liquid Bi. Furthermore, the overpotential associated with deposition of Gd into the liquid Bi electrode gradually increased with current density and decreased with temperature. At the lowest temperature of 773 K, a steep increase in overpotential was evident at high current densities due to slower mass transport and low solubility of Gd in liquid Bi (0.5 at.% Gd). Based on the impedance spectra of Bi electrodes at 773–973 K, the exchange current density was estimated to be 110–220 mA cm −2 , indicating facile charge transfer at the liquid electrode-electrolyte interface. Post-mortem characterization of Bi cathodes after electrolysis at 873 K indicated the formation of a solid GdBi(s) compound layer at the Bi electrode surface. Chemical analysis of Bi cathodes at various deposited Gd compositions resulted in Faradaic efficiencies of ∼75–84 %, promising a high recovery yield of Gd from molten salts using a strongly-interacting liquid Bi electrode.

36 - MATERIALS SCIENCE↗
DOE OSTI2023

Structural Changes to the Gd‐DTPA Complex at Varying Ligand Protonation State

Abstract Diethylenetriaminepentaacetic acid (DTPA) is a chelating agent whose complex with the Gd 3+ ion is used in medical imaging. DTPA is also used in lanthanide‐actinide separation processes. As protonation of the DTPA ligand can facilitate dissociation of the Gd 3+ ion from the Gd‐DTPA complex, this work investigates the coordination structures of the aqueous Gd 3+ ion and its environment when chelated by DTPA in eight different DTPA protonation states. Both classical and ab initio molecular dynamics (MD) simulations are conducted to model the solvated complexes. Extended X‐ray absorption fine structure (EXAFS) measurements of the Gd 3+ aqua ion, and the Gd‐DTPA complex at pH 1 and 11, are compared to EXAFS spectra predicted from the MD simulations to verify the accuracy of the MD structures. The findings of this work provide atomic‐level details into the fluctuating Gd‐DTPA complex environment as the DTPA ligand gradually detaches from the Gd 3+ ion with increased protonation.

Chemistry↗
DOE OSTI2020

The role of low Gd concentrations on magnetisation behaviour in rare earth:transition metal alloy films

The magnetisation reversal behaviour as a function of composition was studied in low rare earth concentration alloys. 30 nm thick rare earth:transition-metal films of composition GdxCo 100-x , GdxFe 100-x and Gd x (Co 50 Fe 50 ) 100-x were prepared by magnetron sputtering, where x ranged from 4 to 13 atomic%. Magnetisation behaviour was studied using MOKE and Hall hysteresis measurements. The magnetic reversal behaviour as a function of Gd content is strongly dependent on the transition metal. With increasing Gd content the film structure transitions from crystalline to amorphous and the saturation magnetisation decreases linearly. For GdCo, the reversal field, Hc, increases by less than a factor of two with Gd doping of 11%, while for Fe, the coercivity falls by a factor of ten with 8% Gd. This may be attributed to changes in the crystalline morphology. GdCoFe shows a similar trend with Gd doping for the in-plane reversal field to that of GdFe. With 13% Gd in Fe there is evidence indicating the presence of a weak perpendicular magnetic anisotropy, PMA. With Gd doping the anomalous Hall resistivity of Co, Fe and CoFe increases significantly with the largest increase observed for GdCoFe.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2025

Coverage-dependent structures and thermodynamic stability of intercalated Gd layers beneath buffer-layer graphene on SiC(0001)

Electronic properties of two-dimensional (2D) materials are strongly influenced by their atomic arrangements, making the theoretically-aided characterization of experimentally-synthesized 2D structures crucial. Using first-principles density functional theory, we analyze nearly 200 configurations of intercalated Gd layers beneath buffer-layer graphene on SiC(0001) over a Gd coverage range of 0.01 < θ < 1.2. By fully relaxing selectively-constructed configurations at each coverage within a large, low-strain supercell, we determine the coverage dependence of the chemical potential for intercalated Gd structures. Thermodynamically-preferred configurations below θ ≈ 0.8 form single-atom-thick monolayers, while 3D-like or multilayer structures emerge beyond θ ≈ 0.9. Most structures are amorphous-like, including the configuration at the chemical potential minimum around θ ≈ 0.4. In contrast, a strongly stretched Gd(0001)-like monolayer at θ = 1/3 and a nearly perfect Gd(0001) monolayer at θ = 1 are significantly less favorable with 0.16 eV and 0.82 eV higher chemical potentials above the minimum, respectively. Furthermore, the graphene layer decoupled by intercalated Gd near the chemical potential minimum is significantly flatter compared to its morphology above intercalated 3D structures at higher coverages and nearly isolated Gd atoms in the lowest coverage region. In conclusion, these findings align with our experimental results and underscore the need for further research on this unique intercalated system, which holds significant potential for diverse applications.

36 MATERIALS SCIENCE↗