Engineering Papers⌕ Search

SEARCH · Engineering Papers

Results for “Gd”

Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 73 records · Page 4
All sourcesNASA NTRSDOE OSTI
DOE OSTI2020

Materials Data on Gd(Cd10Ni)2 by Materials Project

Gd(NiCd10)2 crystallizes in the cubic Fd-3m space group. The structure is three-dimensional. Gd is bonded in a 4-coordinate geometry to sixteen Cd atoms. There are four shorter (3.42 Å) and twelve longer (3.45 Å) Gd–Cd bond lengths. Ni is bonded to twelve Cd atoms to form NiCd12 cuboctahedra that share corners with six equivalent NiCd12 cuboctahedra, edges with eighteen equivalent CdGdCd10Ni cuboctahedra, and faces with six equivalent CdGdCd10Ni cuboctahedra. There are six shorter (2.80 Å) and six longer (3.10 Å) Ni–Cd bond lengths. There are three inequivalent Cd sites. In the first Cd site, Cd is bonded in a distorted linear geometry to two equivalent Ni and ten Cd atoms. There are a spread of Cd–Cd bond distances ranging from 2.98–3.13 Å. In the second Cd site, Cd is bonded to one Gd, one Ni, and ten Cd atoms to form CdGdCd10Ni cuboctahedra that share corners with fifteen equivalent CdGdCd10Ni cuboctahedra, edges with two equivalent CdGdCd10Ni cuboctahedra, edges with three equivalent NiCd12 cuboctahedra, a faceface with one NiCd12 cuboctahedra, and faces with fifteen equivalent CdGdCd10Ni cuboctahedra. There are a spread of Cd–Cd bond distances ranging from 2.90–3.35 Å. In the third Cd site, Cd is bonded in a distorted linear geometry to two equivalent Gd and twelve equivalent Cd atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Gd(Zn10Co)2 by Materials Project

Gd(CoZn10)2 crystallizes in the cubic Fd-3m space group. The structure is three-dimensional. Gd is bonded in a 4-coordinate geometry to sixteen Zn atoms. There are four shorter (3.04 Å) and twelve longer (3.11 Å) Gd–Zn bond lengths. Co is bonded to twelve Zn atoms to form CoZn12 cuboctahedra that share corners with six equivalent CoZn12 cuboctahedra, edges with eighteen equivalent ZnGdZn10Co cuboctahedra, and faces with six equivalent ZnGdZn10Co cuboctahedra. There are six shorter (2.49 Å) and six longer (2.71 Å) Co–Zn bond lengths. There are three inequivalent Zn sites. In the first Zn site, Zn is bonded in a distorted linear geometry to two equivalent Co and ten Zn atoms. There are a spread of Zn–Zn bond distances ranging from 2.64–2.76 Å. In the second Zn site, Zn is bonded to one Gd, one Co, and ten Zn atoms to form distorted ZnGdZn10Co cuboctahedra that share corners with fifteen equivalent ZnGdZn10Co cuboctahedra, edges with two equivalent ZnGdZn10Co cuboctahedra, edges with three equivalent CoZn12 cuboctahedra, a faceface with one CoZn12 cuboctahedra, and faces with fifteen equivalent ZnGdZn10Co cuboctahedra. There are a spread of Zn–Zn bond distances ranging from 2.63–3.01 Å. In the third Zn site, Zn is bonded in a distorted linear geometry to two equivalent Gd and twelve equivalent Zn atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Gd(SiPt)2 by Materials Project

GdPt2Si2 crystallizes in the tetragonal I4/mmm space group. The structure is three-dimensional. Gd is bonded in a 8-coordinate geometry to eight equivalent Pt and eight equivalent Si atoms. All Gd–Pt bond lengths are 3.30 Å. All Gd–Si bond lengths are 3.29 Å. Pt is bonded in a 4-coordinate geometry to four equivalent Gd and four equivalent Si atoms. All Pt–Si bond lengths are 2.42 Å. Si is bonded in a 4-coordinate geometry to four equivalent Gd and four equivalent Pt atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Gd(BC)2 by Materials Project

GdB2C2 crystallizes in the tetragonal P4_2/mmc space group. The structure is three-dimensional. Gd is bonded in a 8-coordinate geometry to eight equivalent B and eight equivalent C atoms. All Gd–B bond lengths are 2.78 Å. All Gd–C bond lengths are 2.75 Å. B is bonded in a 2-coordinate geometry to four equivalent Gd and two equivalent C atoms. Both B–C bond lengths are 1.61 Å. C is bonded in a 2-coordinate geometry to four equivalent Gd, two equivalent B, and one C atom. The C–C bond length is 1.42 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Gd(BRh)4 by Materials Project

GdRh4B4 crystallizes in the tetragonal P4_2/nmc space group. The structure is three-dimensional. Gd is bonded in a 12-coordinate geometry to twelve equivalent Rh and twelve equivalent B atoms. There are four shorter (2.98 Å) and eight longer (3.18 Å) Gd–Rh bond lengths. There are eight shorter (3.04 Å) and four longer (3.15 Å) Gd–B bond lengths. Rh is bonded in a 5-coordinate geometry to three equivalent Gd and five equivalent B atoms. There are a spread of Rh–B bond distances ranging from 2.22–2.26 Å. B is bonded in a 6-coordinate geometry to three equivalent Gd, five equivalent Rh, and one B atom. The B–B bond length is 1.81 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Gd(BC)2 by Materials Project

GdB2C2 crystallizes in the tetragonal P4/mbm space group. The structure is three-dimensional. Gd is bonded in a 8-coordinate geometry to eight equivalent B and eight equivalent C atoms. All Gd–B bond lengths are 2.77 Å. All Gd–C bond lengths are 2.71 Å. B is bonded in a distorted trigonal planar geometry to four equivalent Gd and three equivalent C atoms. There is one shorter (1.53 Å) and two longer (1.60 Å) B–C bond length. C is bonded in a 3-coordinate geometry to four equivalent Gd and three equivalent B atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2024

Advanced neutron absorber Ni-Cr-Mo-Gd alloys seawater corrosion mechanism and susceptibility study

Previous studies demonstrated the corrosion susceptibility of advanced neutron absorber (ANA) Ni-Cr-Mo-Gd in a seawater environment but remained inconclusive. In this paper, scanning electron microscopy was employed to identify the corrosion phase in Ni-Cr-Mo-Gd, and computational thermodynamic simulation was used to study phase corrosion potentials. Results showed that the Ni 5 Gd second phase, distributed along FCC grain boundaries in Ni-Cr-Mo-Gd, has lower corrosion potential than the substrate. Furthermore, heat treatment and alloy chemistry adjustment would not ameliorate the ANA corrosion susceptibility. Finally, isolating the Ni 5 Gd from the corrosion medium through advanced manufacturing is a viable way to improve the ANA corrosion resistance.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Gd by Materials Project

Gd is Tungsten structured and crystallizes in the cubic Im-3m space group. The structure is three-dimensional. Gd is bonded in a distorted body-centered cubic geometry to eight equivalent Gd atoms. All Gd–Gd bond lengths are 3.50 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Gd by Materials Project

Gd is Magnesium structured and crystallizes in the hexagonal P6_3/mmc space group. The structure is three-dimensional. Gd is bonded to twelve equivalent Gd atoms to form a mixture of face, edge, and corner-sharing GdGd12 cuboctahedra. There are six shorter (3.56 Å) and six longer (3.61 Å) Gd–Gd bond lengths.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Gd by Materials Project

Gd is Copper structured and crystallizes in the cubic Fm-3m space group. The structure is three-dimensional. Gd is bonded to twelve equivalent Gd atoms to form a mixture of corner, edge, and face-sharing GdGd12 cuboctahedra. All Gd–Gd bond lengths are 3.57 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Magneto-structural studies of an unusual [Mn III Mn II Gd III (OR) 4 ] 4– partial cubane from 2,2'-bis- p- t Bu-calix[4]arene

Reaction of 2,2'-bis- p - t Bu-calix[4]arene (H 8 L) with MnCl 2 ·4H 2 O, GdCl 3 ·6H 2 O and 2,6-pyridinedimethanol (H 2 pdm) affords [Mn III Mn II Gd III (H 3 L)(pdmH)(pdm)(MeOH) 2 (dmf)]·3MeCN·dmf ( 3 ·3MeCN·dmf) upon vapour diffusion of MeCN into the basic dmf/MeOH mother liquor. 3 crystallises in the tetragonal space group P 4 1 2 1 2 with the asymmetric unit comprising the entire cluster. The highly unusual core contains a triangular arrangement of Mn III Mn II Gd III ions housed within a [Mn III Mn II Gd III (OR) 4 ] 4– partial cubane. Magnetic susceptibility and magnetisation data reveal best fit parameters J Mn(II)–Mn(III) = +0.415 cm –1 , J Mn(III)–Gd(III) = +0.221 cm –1 , J Mn(II)–Gd(III) = –0.258 cm –1 and D Mn(III) = –4.139 cm –1 . Theoretically derived magnetic exchange interactions, anisotropy parameters, and magneto-structural correlations for 3 are in excellent agreement with the experimental data.

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

Unifying femtosecond and picosecond single-pulse magnetic switching in Gd-Fe-Co

Many questions are still open regarding the physical mechanisms behind the magnetic switching in Gd-Fe-Co alloys by single optical pulses. Phenomenological models suggest a femtosecond scale exchange relaxation between sublattice magnetization as the driving mechanism for switching. The recent observation of thermally induced switching in Gd-Fe-Co by using both several picosecond optical laser pulse as well as electric current pulses has questioned this previous understanding. This has raised the question of whether or not the same switching mechanics are acting at the femtosecond and picosecond scales. In this work, we aim at filling this gap in the understanding of the switching mechanisms behind thermal single-pulse switching. To that end, we have studied experimentally thermal single-pulse switching in Gd-Fe-Co alloys, for a wide range of system parameters, such as composition, laser power, and pulse duration. We provide a quantitative description of the switching dynamics using atomistic spin dynamics methods with excellent agreement between the model and our experiments across a wide range of parameters and timescales, ranging from femtoseconds to picoseconds. Furthermore, we find distinct element-specific damping parameters as a key ingredient for switching with long picosecond pulses and argue that switching with pulse durations as long as 15 ps is possible due to a low damping constant of Gd. Our findings can be easily extended to speed up dynamics in other contexts where ferrimagnetic Gd-Fe-Co alloys have been already demonstrated to show fast and energy-efficient processes, e.g., domain-wall motion in a track and spin-orbit torque switching in spintronics devices.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2020

Identification of new transitions and levels in 163 Gd from $β$-decay studies

Background: Neutron-rich nuclei in the mass region around A = 160 have been and will continue to be of interest for the study of nuclear structure because of the rapid onset of deformation between 88 and 90 neutrons. The observation of detailed changes in nuclear structures within this mass region has provided and will continue to provide insight into the nuclear force. Purpose: Investigations of γ rays emitted following Eu 163 β -decay to Gd 163 have been performed for evaluation of the nuclear structure of Gd 163 . Method: Data were collected at the LeRIBSS station of the Holifield Radioactive Ion Beam Facility at Oak Ridge National Laboratory with an array of four Clover HPGe detectors for γ -rays and two plastic scintillators for β detection. The γ rays were identified as belonging to Gd 163 via mass selection and γ – γ – β , x-ray- γ , or γ – γ coincidences. Results: In total 107 new γ -ray transitions were observed in Gd 163 from 53 newly identified levels. Conclusions: We report the structure of Gd 163 has been identified for the first time. This structure has been evaluated in comparison to projected shell model, and potential energy surface calculations with good agreement.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2021

Long-lived isomeric states and quasiparticle band structures in neutron-rich 162,164 Gd nuclei from β decay

Neutron-rich nuclei 162,164 Eu were produced by bombarding a proton beam on a 238 U target at the Holifield Radioactive Ion Beam Facility at Oak Ridge National Laboratory and mass separating the 162,164 Eu products. New level schemes and new γ-ray transitions of the daughters 162,164 Gd were identified from β-decay spectroscopy studies. Additionally, half-lives of the 162,164 Eu were remeasured to clarify the previous ambiguous results. Two quasiparticle band structures were built and compared with neighboring nuclei. The β and γ bands were extended in 162 Gd and a γ band was extended in 164 Gd. Half-lives of the isomeric states at (6 - ) 1449 keV in 162 Gd and (4 - ) 1096 keV in 164 Gd were measured to be 99(3) μs and 0.56(3) μs, respectively. Projected shell model calculations were performed and found to be in good agreement with all of the experimental data.

150 ≤ A ≤ 189↗
DOE OSTI2024

Performance of SK-Gd’s Upgraded Real-time Supernova Monitoring System

Among multimessenger observations of the next Galactic core-collapse supernova, Super-Kamiokande (SK) plays a critical role in detecting the emitted supernova neutrinos, determining the direction to the supernova (SN), and notifying the astronomical community of these observations in advance of the optical signal. In 2022, SK has increased the gadolinium dissolved in its water target (SK-Gd) and has achieved a Gd concentration of 0.033%, resulting in enhanced neutron detection capability, which in turn enables more accurate determination of the supernova direction. Accordingly, SK-Gd’s real-time supernova monitoring system has been upgraded. SK_SN Notice, a warning system that works together with this monitoring system, was released on 2021 December 13, and is available through GCN Notices. When the monitoring system detects an SN-like burst of events, SK_SN Notice will automatically distribute an alarm with the reconstructed direction to the supernova candidate within a few minutes. In this paper, we present a systematic study of SK-Gd’s response to a simulated Galactic SN. Assuming a supernova situated at 10 kpc, neutrino fluxes from six supernova models are used to characterize SK-Gd’s pointing accuracy using the same tools as the online monitoring system. The pointing accuracy is found to vary from 3° to 7° depending on the models. However, if the supernova is closer than 10 kpc, SK_SN Notice can issue an alarm with three-degree accuracy, which will benefit follow-up observations by optical telescopes with large fields of view.

Core-collapse supernovae↗
NASA NTRS2006

A Chandra Search for Coronal X Rays from the Cool White Dwarf GD 356

We report observations with the Chandra X-ray Observatory of the single, cool, magnetic white dwarf GD 356. For consistent comparison with other X-ray observations of single white dwarfs, we also re-analyzed archival ROSAT data for GD 356 (GJ 1205), G 99-47 (GR 290 = V1201 Ori), GD 90, G 195-19 (EG250 = GJ 339.1), and WD 2316+123 and archival Chandra data for LHS 1038 (GJ 1004) and GD 358 (V777 Her). Our Chandra observation detected no X rays from GD 356, setting the most restrictive upper limit to the X-ray luminosity from any cool white dwarf - Lx less than 6.0 x 10(exp 25) erg s(sup -1), at 99.7% confidence, for a 1- keV thermal-bremsstrahlung spectrum. The corresponding limit to the electron density is no less than 4.4x10(exp 11) per cubic centimeter. Our re-analysis of the archival data confirmed the non-detections reported by the original investigators. We discuss the implications of our and prior observations on models for coronal emission from white dwarfs. For magnetic white dwarfs, we emphasize the more stringent constraints imposed by cyclotron radiation. In addition, we describe (in an appendix) a statistical methodology for detecting a source and for constraining the strength of a source, which applies even when the number of source or background events is small.

Weisskopf, Martin C.↗
DOE OSTI2020

Materials Data on Gd(PdO2)2 by Materials Project

Gd(PdO2)2 crystallizes in the tetragonal I4_1/a space group. The structure is three-dimensional. Gd is bonded in a 8-coordinate geometry to eight equivalent O atoms. There are four shorter (2.37 Å) and four longer (2.50 Å) Gd–O bond lengths. Pd is bonded in a square co-planar geometry to four equivalent O atoms. There are two shorter (2.03 Å) and two longer (2.04 Å) Pd–O bond lengths. O is bonded to two equivalent Gd and two equivalent Pd atoms to form a mixture of edge and corner-sharing OGd2Pd2 tetrahedra.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Gd(Al10Cr)2 by Materials Project

GdCr2Al20 crystallizes in the cubic Fd-3m space group. The structure is three-dimensional. Gd is bonded in a 4-coordinate geometry to sixteen Al atoms. There are four shorter (3.13 Å) and twelve longer (3.21 Å) Gd–Al bond lengths. Cr is bonded to twelve Al atoms to form CrAl12 cuboctahedra that share corners with six equivalent CrAl12 cuboctahedra, edges with eighteen equivalent AlGdAl10Cr cuboctahedra, and faces with six equivalent AlGdAl10Cr cuboctahedra. There are six shorter (2.56 Å) and six longer (2.78 Å) Cr–Al bond lengths. There are three inequivalent Al sites. In the first Al site, Al is bonded in a 12-coordinate geometry to two equivalent Cr and ten Al atoms. There are a spread of Al–Al bond distances ranging from 2.71–2.82 Å. In the second Al site, Al is bonded to one Gd, one Cr, and ten Al atoms to form distorted AlGdAl10Cr cuboctahedra that share corners with fifteen equivalent AlGdAl10Cr cuboctahedra, edges with two equivalent AlGdAl10Cr cuboctahedra, edges with three equivalent CrAl12 cuboctahedra, a faceface with one CrAl12 cuboctahedra, and faces with fifteen equivalent AlGdAl10Cr cuboctahedra. There are a spread of Al–Al bond distances ranging from 2.72–3.10 Å. In the third Al site, Al is bonded in a distorted linear geometry to two equivalent Gd and twelve equivalent Al atoms.

36 MATERIALS SCIENCE↗