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At least 937 records · Page 52
All sourcesNASA NTRSDOE OSTI
DOE OSTI2020

Materials Data on PrGdZn2 by Materials Project

GdPrZn2 is Heusler-like structured and crystallizes in the tetragonal P4/mmm space group. The structure is three-dimensional. Gd is bonded in a body-centered cubic geometry to eight equivalent Zn atoms. All Gd–Zn bond lengths are 3.13 Å. Pr is bonded in a body-centered cubic geometry to eight equivalent Zn atoms. All Pr–Zn bond lengths are 3.23 Å. Zn is bonded in a body-centered cubic geometry to four equivalent Gd and four equivalent Pr atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on GdY3 by Materials Project

GdY3 is Uranium Silicide structured and crystallizes in the cubic Pm-3m space group. The structure is three-dimensional. Gd is bonded to twelve equivalent Y atoms to form GdY12 cuboctahedra that share corners with twelve equivalent GdY12 cuboctahedra, edges with twenty-four equivalent YGd4Y8 cuboctahedra, faces with six equivalent GdY12 cuboctahedra, and faces with twelve equivalent YGd4Y8 cuboctahedra. All Gd–Y bond lengths are 3.60 Å. Y is bonded to four equivalent Gd and eight equivalent Y atoms to form YGd4Y8 cuboctahedra that share corners with twelve equivalent YGd4Y8 cuboctahedra, edges with eight equivalent GdY12 cuboctahedra, edges with sixteen equivalent YGd4Y8 cuboctahedra, faces with four equivalent GdY12 cuboctahedra, and faces with fourteen equivalent YGd4Y8 cuboctahedra. All Y–Y bond lengths are 3.60 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on GdThRu2 by Materials Project

ThGdRu2 is Heusler structured and crystallizes in the cubic Fm-3m space group. The structure is three-dimensional. Th is bonded in a body-centered cubic geometry to eight equivalent Ru atoms. All Th–Ru bond lengths are 3.02 Å. Gd is bonded in a body-centered cubic geometry to eight equivalent Ru atoms. All Gd–Ru bond lengths are 3.02 Å. Ru is bonded in a body-centered cubic geometry to four equivalent Th and four equivalent Gd atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on GdLuRh2 by Materials Project

LuGdRh2 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 Rh atoms. All Lu–Rh bond lengths are 2.96 Å. Gd is bonded in a body-centered cubic geometry to eight equivalent Rh atoms. All Gd–Rh bond lengths are 2.96 Å. Rh is bonded in a body-centered cubic geometry to four equivalent Lu and four equivalent Gd atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on GdMgAu2 by Materials Project

MgGdAu2 is Heusler structured and crystallizes in the cubic Fm-3m space group. The structure is three-dimensional. Mg is bonded in a body-centered cubic geometry to eight equivalent Au atoms. All Mg–Au bond lengths are 3.03 Å. Gd is bonded in a body-centered cubic geometry to eight equivalent Au atoms. All Gd–Au bond lengths are 3.03 Å. Au is bonded in a body-centered cubic geometry to four equivalent Mg and four equivalent Gd atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on GdYRh2 by Materials Project

GdYRh2 is Heusler structured and crystallizes in the cubic Fm-3m space group. The structure is three-dimensional. Gd is bonded in a body-centered cubic geometry to eight equivalent Rh atoms. All Gd–Rh bond lengths are 2.99 Å. Y is bonded in a body-centered cubic geometry to eight equivalent Rh atoms. All Y–Rh bond lengths are 2.99 Å. Rh is bonded in a body-centered cubic geometry to four equivalent Gd and four equivalent Y atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Gd3MoO7 by Materials Project

Gd3MoO7 crystallizes in the orthorhombic P2_12_12_1 space group. The structure is three-dimensional. there are three inequivalent Gd3+ sites. In the first Gd3+ site, Gd3+ is bonded in a 7-coordinate geometry to seven O2- atoms. There are a spread of Gd–O bond distances ranging from 2.33–2.68 Å. In the second Gd3+ site, Gd3+ is bonded to seven O2- atoms to form distorted GdO7 pentagonal bipyramids that share corners with two equivalent MoO6 octahedra, corners with three GdO7 pentagonal bipyramids, edges with two equivalent MoO6 octahedra, and edges with two equivalent GdO7 pentagonal bipyramids. The corner-sharing octahedra tilt angles range from 30–36°. There are a spread of Gd–O bond distances ranging from 2.32–2.60 Å. In the third Gd3+ site, Gd3+ is bonded to seven O2- atoms to form distorted GdO7 pentagonal bipyramids that share corners with two equivalent MoO6 octahedra, corners with three GdO7 pentagonal bipyramids, edges with two equivalent MoO6 octahedra, and edges with two equivalent GdO7 pentagonal bipyramids. The corner-sharing octahedra tilt angles range from 45–47°. There are a spread of Gd–O bond distances ranging from 2.24–2.57 Å. Mo5+ is bonded to six O2- atoms to form MoO6 octahedra that share corners with two equivalent MoO6 octahedra, corners with four GdO7 pentagonal bipyramids, and edges with four GdO7 pentagonal bipyramids. The corner-sharing octahedral tilt angles are 40°. There are a spread of Mo–O bond distances ranging from 1.89–2.12 Å. There are seven inequivalent O2- sites. In the first O2- site, O2- is bonded in a 4-coordinate geometry to three Gd3+ and one Mo5+ atom. In the second O2- site, O2- is bonded to four Gd3+ atoms to form a mixture of corner and edge-sharing OGd4 tetrahedra. In the third O2- site, O2- is bonded to four Gd3+ atoms to form OGd4 tetrahedra that share corners with eight OGd4 tetrahedra and edges with two OGd3Mo tetrahedra. In the fourth O2- site, O2- is bonded in a 4-coordinate geometry to two Gd3+ and two equivalent Mo5+ atoms. In the fifth O2- site, O2- is bonded to three Gd3+ and one Mo5+ atom to form a mixture of corner and edge-sharing OGd3Mo tetrahedra. In the sixth O2- site, O2- is bonded in a 3-coordinate geometry to two Gd3+ and one Mo5+ atom. In the seventh O2- site, O2- is bonded in a 4-coordinate geometry to three Gd3+ and one Mo5+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on LiGdO3 by Materials Project

LiGdO3 is (Cubic) Perovskite structured and crystallizes in the cubic Pm-3m space group. The structure is three-dimensional. Li is bonded to six equivalent O atoms to form LiO6 octahedra that share corners with six equivalent LiO6 octahedra and faces with eight equivalent GdO12 cuboctahedra. The corner-sharing octahedral tilt angles are 0°. All Li–O bond lengths are 1.85 Å. Gd is bonded to twelve equivalent O atoms to form GdO12 cuboctahedra that share corners with twelve equivalent GdO12 cuboctahedra, faces with six equivalent GdO12 cuboctahedra, and faces with eight equivalent LiO6 octahedra. All Gd–O bond lengths are 2.62 Å. O is bonded in a distorted linear geometry to two equivalent Li and four equivalent Gd atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Li3GdO3 by Materials Project

Li3GdO3 crystallizes in the trigonal P-3c1 space group. The structure is three-dimensional. there are three inequivalent Li1+ sites. In the first Li1+ site, Li1+ is bonded to four O2- atoms to form LiO4 tetrahedra that share corners with four GdO6 octahedra, corners with six LiO4 tetrahedra, edges with two GdO6 octahedra, and edges with three LiO4 tetrahedra. The corner-sharing octahedra tilt angles range from 25–57°. There are a spread of Li–O bond distances ranging from 1.97–2.18 Å. In the second Li1+ site, Li1+ is bonded to four O2- atoms to form LiO4 tetrahedra that share corners with four GdO6 octahedra, corners with six LiO4 tetrahedra, edges with two GdO6 octahedra, and edges with three LiO4 tetrahedra. The corner-sharing octahedra tilt angles range from 24–57°. There are a spread of Li–O bond distances ranging from 1.97–2.19 Å. In the third Li1+ site, Li1+ is bonded to four O2- atoms to form LiO4 tetrahedra that share corners with four GdO6 octahedra, corners with six LiO4 tetrahedra, edges with two GdO6 octahedra, and edges with three LiO4 tetrahedra. The corner-sharing octahedra tilt angles range from 25–57°. There are a spread of Li–O bond distances ranging from 1.97–2.18 Å. There are three inequivalent Gd3+ sites. In the first Gd3+ site, Gd3+ is bonded to six O2- atoms to form GdO6 octahedra that share corners with twelve LiO4 tetrahedra, edges with three GdO6 octahedra, and edges with six LiO4 tetrahedra. There are two shorter (2.32 Å) and four longer (2.33 Å) Gd–O bond lengths. In the second Gd3+ site, Gd3+ is bonded to six O2- atoms to form GdO6 octahedra that share corners with twelve LiO4 tetrahedra, edges with three equivalent GdO6 octahedra, and edges with six LiO4 tetrahedra. There are three shorter (2.33 Å) and three longer (2.34 Å) Gd–O bond lengths. In the third Gd3+ site, Gd3+ is bonded to six equivalent O2- atoms to form GdO6 octahedra that share corners with twelve LiO4 tetrahedra, edges with three equivalent GdO6 octahedra, and edges with six equivalent LiO4 tetrahedra. All Gd–O bond lengths are 2.34 Å. There are three inequivalent O2- sites. In the first O2- site, O2- is bonded to four Li1+ and two Gd3+ atoms to form a mixture of distorted edge and corner-sharing OLi4Gd2 pentagonal pyramids. In the second O2- site, O2- is bonded to four Li1+ and two Gd3+ atoms to form a mixture of distorted edge and corner-sharing OLi4Gd2 pentagonal pyramids. In the third O2- site, O2- is bonded to four Li1+ and two Gd3+ atoms to form a mixture of distorted edge and corner-sharing OLi4Gd2 pentagonal pyramids.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Gd3Cu2Te7 by Materials Project

Gd3Cu2Te7 crystallizes in the orthorhombic Ama2 space group. The structure is three-dimensional. there are three inequivalent Gd3+ sites. In the first Gd3+ site, Gd3+ is bonded in a 8-coordinate geometry to eight Te+1.86- atoms. There are a spread of Gd–Te bond distances ranging from 3.05–3.28 Å. In the second Gd3+ site, Gd3+ is bonded in a 8-coordinate geometry to eight Te+1.86- atoms. There are a spread of Gd–Te bond distances ranging from 3.00–3.28 Å. In the third Gd3+ site, Gd3+ is bonded in a 8-coordinate geometry to eight Te+1.86- atoms. There are a spread of Gd–Te bond distances ranging from 3.05–3.28 Å. There are two inequivalent Cu2+ sites. In the first Cu2+ site, Cu2+ is bonded in a distorted tetrahedral geometry to four Te+1.86- atoms. There are a spread of Cu–Te bond distances ranging from 2.61–2.73 Å. In the second Cu2+ site, Cu2+ is bonded in a 4-coordinate geometry to four Te+1.86- atoms. There are a spread of Cu–Te bond distances ranging from 2.54–2.68 Å. There are six inequivalent Te+1.86- sites. In the first Te+1.86- site, Te+1.86- is bonded in a 4-coordinate geometry to four Gd3+ atoms. In the second Te+1.86- site, Te+1.86- is bonded to four Gd3+ and one Cu2+ atom to form a mixture of edge and corner-sharing TeGd4Cu trigonal bipyramids. In the third Te+1.86- site, Te+1.86- is bonded in a 6-coordinate geometry to four Gd3+ and two Cu2+ atoms. In the fourth Te+1.86- site, Te+1.86- is bonded to four Gd3+ and one Cu2+ atom to form a mixture of distorted edge and corner-sharing TeGd4Cu trigonal bipyramids. In the fifth Te+1.86- site, Te+1.86- is bonded in a 4-coordinate geometry to two Gd3+ and two Cu2+ atoms. In the sixth Te+1.86- site, Te+1.86- is bonded in a 4-coordinate geometry to four Gd3+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2023

High‐Throughput Evaluation of Hardening Coefficients of Eight Alloying Elements in Magnesium

Liquid–solid diffusion couples (LSDCs) are employed to generate a composition gradient in the single‐phase hexagonal closed‐packed (hcp) solid solution with compositions up to the solubility limit of various solutes in Mg. Nanoindentation scanning across the composition gradient in LSDCs allows effective evaluation of composition‐dependent hardness of eight alloying elements (Al, Ca, Ce, Gd, Li, Sn, Y, and Zn) in the hcp Mg phase. The hardening coefficients, an indicator of the potency of solid‐solution hardening, are evaluated from the measured composition‐hardness data and correlated with various materials properties such as atomic radius, shear modulus, and elastic modulus of the solutes. The rank of hardening potency of Al, Gd, Sn, Y, and Zn measured by nanoindentation is in good agreement with that measured by microindentation reported in the literature. The hardening coefficient (potency) from the strongest to the weakest is Ce > Ca > Y ≈ Gd > Zn > Al ≈ Sn > Li in Mg‐based hcp binary solid solutions. The hardening coefficient is found to be closely correlated with the strengthening potency.

36 MATERIALS SCIENCE↗
DOE OSTI2025

Speciation and diffusive dynamics in hydrated grain boundaries of complex oxide Gd2Ti2O7

Abstract Grain boundaries in polycrystalline materials significantly affect their properties, such as ionic transport, corrosion, and chemical durability. The pyrochlore compound (Gd 2 Ti 2 O 7 ) is employed as a model for complex oxides and is known for its diverse applications, including nuclear waste immobilization. Density functional theory-based first-principles molecular dynamics simulations were performed at different temperatures on the hydrated grain boundary system. The results show extensive transformations within the grain boundaries among hydrous water species (OH − , H 2 O, and H 3 O + ). The temperature dependence of self-diffusion coefficients follows Arrhenius behavior, with an activation energy of 35.9 kJ/mol for hydrogen and 46.3 kJ/mol for oxygen. The lifetime of OH − is about three to four times longer than that of H 2 O at temperatures from 800 to 2100 K, suggesting the greater stability of OH − over H 2 O, a unique characteristic of the grain boundaries. The estimated lifetime of the hydrous species decreases as the temperature increases, with an activation energy of 9.9 kJ/mol for OH − and 13.4 kJ/mol for H 2 O. While Gd 3 + is more mobile than Ti 4+ , both the Gd 3 + and Ti 4+ cations are orders of magnitude less mobile than the water species. The results suggest that water species are much more mobile within grain boundaries than in the bulk crystal and have the potential to penetrate deep into polycrystalline materials through grain boundaries, leading to grain boundary degradation and dissolution. The different mobilities of cations in complex oxides can lead to leaching of certain cations and incongruent dissolution during the chemical weathering of Earth and industrial materials.

B. Ghosh, Dipta↗
DOE OSTI2025

Separation of terbium from proton-irradiated gadolinium oxide targets – development of an effective, scalable and automatable process

This work reports an effective and scalable radiochemical separation process for isolating terbium from Gd 2 O 3 . The separation process uses three commercially available extraction chromatography resin columns, has been implemented on a computer-controlled chemistry module, and tested with 100 mg quantities of proton-irradiated nat Gd 2 O 3 . Here, the 4-hour separation procedure isolated radioterbium in 1.3 mL of 0.01 M HCl with 80 ±8% radiochemical yield and a Gd decontamination factor >(1.2 ± 0.3)·10 5 .

Adjacent lanthanide separation↗
DOE OSTI2020

Distribution of rare earth elements in fly ash derived from the combustion of Illinois Basin coals

This study examined rare earth element (REE) trends for Illinois Basin coal-sourced fly ashes, with the goal of understanding the elemental composition and resource potential for various fly ash fractions. Illinois Basin coals have a high volatile C through A bituminous rank with a moderate ash content (slightly>12% ash (dry basis)), about 3% sulfur, and, in general, lower concentrations of hazardous and other trace elements than many Central Appalachian coals. Fly ash from the combustion of Illinois Basin coals tends to have a high Fe 2 O 3 content owing to the amount of pyrite in the feed coals. The rare earth element (REE) concentrations in Illinois Basin coal-sourced fly ashes are less than that for fly ashes from the combustion of Central Appalachian coals. The Upper continental crust-corrected fly ashes show an H-type enrichment, a positive Eu N /Eu N * , and, in some cases, a sharp Gd peak. For comparison, a suite of fly ashes from the combustion of a blend of eastern Kentucky coals had an H-type enrichment, a positive Eu N /Eu N * , but only a minimal Gd peak. In contrast, fly ash from the combustion of the Fire Clay coal, a REE-rich coal, had a negative Eu N /Eu N * and a sharp Gd peak. Finally, these results highlight the importance of feed coal composition on trace element contents of respective combustion fly ash fractions and also the unique REE enrichment patterns of the Illinois Basin fly ashes relative to the better studied fly ashes of eastern Kentucky and Central Appalachia.

01 COAL, LIGNITE, AND PEAT↗
DOE OSTI2021

Distribution of rare earth elements in the pilot-scale processing of fly ashes derived from eastern Kentucky coals: Comparisons of the feed and processed ashes

Beneficiated fly ash from the combustion of Central Appalachian high volatile bituminous coals was extracted with HNO 3 in a pilot-scale processing plant. Several major oxides (notably CaO and SO 3 , but also including Fe 2 O 3 , MgO, K 2 O, and P 2 O 5 ) and minor elements (Mn, As, Sr, Ba, and Pb) are depleted in the post-HNO 3 -extraction spent ash. The total lanthanides, Y, and Sc concentration is reduced by about 20% in the spent ash, with Gd showing the greatest decrease. Along with Gd, Nd and Dy are also well differentiated between the feed and spent ashes, with La and Sm showing minimal partitioning. The Gd decrease is correlated with the depletion of Fe 2 O 3 . The heavy rare earth elements (REE heavier than Eu) and Y are disproportionately concentrated in the HNO 3 -leachate compared to the light REE. For the ashes studied, Sc did not partition between the feed and spent ashes. Pozzolanicity tests show that the compressive strength and strength activity indices of the spent ash + ordinary Portland cement (OPC) mixes are comparable to 100% OPC, indicating that the spent ashes produced in the pilot-scale runs have the potential to be sold as a Class F fly ash. Finally, the beneficiated ash chemistry influences the chemistry of the post-HNO 3 -extraction spent ash and the HNO 3 -leachate. A 500-ppm-REE fly ash will presumably be a more economically favorable feedstock than an ash with a significantly lesser concentration.

01 COAL, LIGNITE, AND PEAT↗
DOE OSTI2020

Using numerical methods to screen magnetocaloric materials in an active magnetic regenerative cycle

A 2-dimensional numerical model of a room temperature operating Active Magnetic Regenerator (AMR) that comprises of a regenerator, hot and cold heat exchangers, heat transfer fluid is developed. The regenerator is made of a magnetocaloric material (MCM) which heats up upon applying a magnetic field, H, and cools down when the field is removed; thus, making it the most essential part of an AMR. The model takes experimentally measured ΔT ad (H,T) and the C p (H,T) data as input and provides quantitative performance metrics of the magnetic cooling system, such as ΔT span and the cooling load, as output. With this model, it is possible to assess a wide range of MCMs in an AMR. 4 different MCMs were investigated using this model in terms of their ΔT span and the cooling loads—LaFe 10.96 Co 0.97 Si 1.07 , MnFeP (1-x) As (x) and AlFe 2 B 2 and Gd. During the screening of MCMs, all the important operating conditions of the device were fixed such as the fluid flow rate, ambient temperature, cycle duration, magnetic field strength. Our results indicate that Gd exhibits the maximum ΔT span with respectable cooling load, while AlFe 2 B 2 generates the lowest ΔT span . Even though LaFeCoSi compound did not perform as well as Gd, it could be the MCM choice for the realization of magnetic refrigeration on a global scale due to its much lower cost.

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 OSTI2023

Investigation of the silicon coated film characteristics on tungsten surface in EAST fusion device

Siliconization using 10 % SiD 4 + 90 % He assisted by ion cyclotron range of frequency discharge (ICRF) or glow discharge (GD) was performed in EAST with full tungsten (W) diverters. It was found that the coated Si film on W sample at a higher baking temperature (160 °C) was smoother than that at a lower baking temperature (60 °C). This was mainly because physically adsorbed gaseous impurities were released at a higher baker temperature. This process improved the adhesion between the film and the surface of W. An increase in the ICRF working power from 20 kW to 40 kW further increased the Si content and the film thickness by 1.5 times. The cleaning efficiency of ICRF on the surface of the W sample before siliconization was higher at 40 kW than that at 20 kW, which facilitated the removal of oxides and other compounds from the surface of W. The ratio of silicon/oxygen (Si/O) and the thickness improved considerably due to greater ionization and deposition of SiD 4 . Additionally, siliconization via GD was more uniform and 1.5 nm thicker than that via ICRF, which was because of the greater working gas pressure, coating duration, and homogeneity in GD. These results might be used as a reference for evaluating the effect of siliconization on plasma performance and its application in fusion devices.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗