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27 records · Page 2
All sourcesNASA NTRSDOE OSTI
DOE OSTI2020

Materials Data on K2PdC4(SN)4 by Materials Project

K2PdC4(NS)4 crystallizes in the monoclinic P2_1/c space group. The structure is three-dimensional. K1+ is bonded in a 4-coordinate geometry to five N3- and three S2- atoms. There are a spread of K–N bond distances ranging from 2.78–3.27 Å. There are a spread of K–S bond distances ranging from 3.41–3.73 Å. Pd2+ is bonded in a square co-planar geometry to four S2- atoms. All Pd–S bond lengths are 2.39 Å. There are two inequivalent C4+ sites. In the first C4+ site, C4+ is bonded in a distorted linear geometry to one N3- and one S2- atom. The C–N bond length is 1.18 Å. The C–S bond length is 1.66 Å. In the second C4+ site, C4+ is bonded in a distorted linear geometry to one N3- and one S2- atom. The C–N bond length is 1.19 Å. The C–S bond length is 1.65 Å. There are two inequivalent N3- sites. In the first N3- site, N3- is bonded in a 1-coordinate geometry to three equivalent K1+ and one C4+ atom. In the second N3- site, N3- is bonded in a 1-coordinate geometry to two equivalent K1+ and one C4+ atom. There are two inequivalent S2- sites. In the first S2- site, S2- is bonded in a 2-coordinate geometry to two equivalent K1+, one Pd2+, and one C4+ atom. In the second S2- site, S2- is bonded in a distorted water-like geometry to one K1+, one Pd2+, and one C4+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2022

The high-pressure lithium–palladium and lithium–palladium–hydrogen systems

Abstract The lithium–palladium and lithium–palladium–hydrogen systems are investigated at high pressures at and above room temperature. Two novel lithium–palladium compounds are found below $${18.7}\,{\mathrm{GPa}}$$ 18.7 GPa . An ambient temperature phase is tentatively assigned as $$F{\bar{4}}3m\,\hbox {Li}_{17}\hbox {Pd}_{4}$$ F 4 ¯ 3 m Li 17 Pd 4 , with $$a = 17.661(1)$$ a = 17.661 ( 1 ) Å at 8.64 GPa, isostructural with $$\hbox {Li}_{17}\hbox {Sn}_{4}$$ Li 17 Sn 4 . The other phase occurs at high-temperature and is $$I{\bar{4}}3m\, \hbox {Li}_{11}\hbox {Pd}_{2}$$ I 4 ¯ 3 m Li 11 Pd 2 , $$a = 9.218(1)$$ a = 9.218 ( 1 ) Å at 3.88 GPa and 200 $$^\circ {\mathrm{C}}$$ ∘ C , similar to $$\hbox {Li}_{11}\hbox {Pt}_{2}$$ Li 11 Pt 2 , which is also known at high pressure. The presence of hydrogen in the system results in an $$I{\bar{4}}3m$$ I 4 ¯ 3 m structure with $$a = 8.856(1)$$ a = 8.856 ( 1 ) Å at 9.74 GPa. This persists up to $${13.3}\,\mathrm{GPa}$$ 13.3 GPa , the highest pressure studied. Below $${2}\,{\mathrm{GPa}}$$ 2 GPa an fcc phase with a large unit cell, $$a = 19.324(1)$$ a = 19.324 ( 1 ) Å at 0.39 GPa, is also observed in the presence of hydrogen. On heating the hydrogen containing system at 4 GPa the $$I{\bar{4}}3m$$ I 4 ¯ 3 m phases persists to the melting point of lithium. In both systems melting the lithium results in the loss of crystalline diffraction from palladium containing phases. This is attributed to dissolution of the palladium in the molten lithium, and on cooling the palladium remains dispersed.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2020

Materials Data on SnPd2 by Materials Project

Pd2Sn is Cotunnite structured and crystallizes in the orthorhombic Pnma space group. The structure is three-dimensional. there are two inequivalent Pd sites. In the first Pd site, Pd is bonded in a 4-coordinate geometry to six equivalent Pd and five equivalent Sn atoms. There are a spread of Pd–Pd bond distances ranging from 2.96–3.20 Å. There are a spread of Pd–Sn bond distances ranging from 2.71–3.04 Å. In the second Pd site, Pd is bonded in a 5-coordinate geometry to eight Pd and five equivalent Sn atoms. Both Pd–Pd bond lengths are 2.92 Å. There are a spread of Pd–Sn bond distances ranging from 2.75–3.00 Å. Sn is bonded in a 10-coordinate geometry to ten Pd atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on ZrSnPd by Materials Project

PdZrSn is half-Heusler structured and crystallizes in the cubic F-43m space group. The structure is three-dimensional. Zr is bonded in a 4-coordinate geometry to six equivalent Pd and four equivalent Sn atoms. All Zr–Pd bond lengths are 3.26 Å. All Zr–Sn bond lengths are 2.82 Å. Pd is bonded in a 10-coordinate geometry to six equivalent Zr and four equivalent Sn atoms. All Pd–Sn bond lengths are 2.82 Å. Sn is bonded in a body-centered cubic geometry to four equivalent Zr and four equivalent Pd atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2021

Iodine Vapor Reactions with Pure Metal Wires at Temperatures of 100–139 °C in Air

In this work, I 2(g) reactions with 11 metal wires (i.e., Al, Ag, Cu, In, Mo, Nb, Ni, Pd, Pt, Sn, Ta) were evaluated at three temperatures (i.e., 100 ± 3°C, 123 ± 4°C, 139 ± 5°C) with exposure times of 24 hours at each temperature. Over these temperatures, some of the metals showed increased mass gain with higher temperatures (i.e., In, Ag, Cu), Sn showed decreased iodine capture at increased temperatures, and most metals (i.e., Mo, Nb, Ni, Pd, Pt, and Ta) showed little to no mass gain at all temperatures. Silver mordenite (AgZ) was used as a standard during these studies and showed a consistent mass gain (m% I ) of 10.6 → 12.8% over this temperature range. The values of mass of iodine captured per mass of starting metal (g g -1 ) ranged widely across the study with the highest values achieved for (in descending order) Sn-T 100°C (4.37), In-T 139°C (3.34), Sn-T 123°C (1.98), In-T 123°C (1.57), Ag-T 139°C (1.19), In-T 100°C (0.97), and Cu-T 139°C (0.71). In some cases, the metal-iodide complex was not stable at the experimental temperature and it was clear some volatility had occurred during the experiment based on discoloration in the vials. These results show that some metals can have extensive reactions with I 2(g) without showing metal-iodide preferences over metal-oxide formation based on thermodynamic predictions. It is possible that materials such as these could be implemented near nuclear facilities to getter I 2(g) in the event of a nuclear accident.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2020

Microstructure and diffusion behavior of uranium fuel with minor additives

Fission product lanthanides in metallic fuels are known to cause adverse fuel-cladding chemical interaction (FCCI). Tin (Sn) and palladium (Pd) are being explored as the potential additives to reduce or mitigate lanthanide-induced FCCI by forming stable Sn-Ln and Pd-Ln compounds. The current study is an investigation of the fuel alloys, U–4Sn, U–4Sn-4Ln, U–4Pd, and U–4Pd-4Ln (wt. %), and their diffusion behaviors with Fe. Microstructural analysis was performed using scanning electron microscopy (SEM). Further, the binary phases in the UPd and USn alloys are identified as UPd 3 and suspected U 2 Sn, where U 2 Sn is unknown in the literature. The binary phases in the UPdLn alloy are identified as PdLn and Pd-rich Pd-Ln (Pd 4 Ln 3 and Pd 3 Ln 2 ), and in the USnLn alloy is SnLn. Diffusion of Fe with these binary phases is insignificant compared to the diffusion with U. The Ln-induced FCCI can be mitigated by the additives.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗
DOE OSTI2020

Materials Data on Ce8SnPd24 by Materials Project

Ce8Pd24Sn crystallizes in the cubic Pm-3m space group. The structure is three-dimensional. Ce is bonded to twelve Pd atoms to form CePd12 cuboctahedra that share corners with twelve equivalent CePd12 cuboctahedra, edges with six equivalent PdCe4Pd8 cuboctahedra, faces with three equivalent PdCe4Pd8 cuboctahedra, faces with six equivalent CePd12 cuboctahedra, and a faceface with one SnPd6 octahedra. There are six shorter (3.01 Å) and six longer (3.03 Å) Ce–Pd bond lengths. There are three inequivalent Pd sites. In the first Pd site, Pd is bonded in a 4-coordinate geometry to four equivalent Ce and two equivalent Pd atoms. Both Pd–Pd bond lengths are 2.93 Å. In the second Pd site, Pd is bonded to four equivalent Ce and eight Pd atoms to form distorted PdCe4Pd8 cuboctahedra that share edges with eight equivalent CePd12 cuboctahedra, faces with four equivalent CePd12 cuboctahedra, and faces with six equivalent PdCe4Pd8 cuboctahedra. All Pd–Pd bond lengths are 2.94 Å. In the third Pd site, Pd is bonded in a 5-coordinate geometry to four equivalent Ce and one Sn atom. The Pd–Sn bond length is 2.68 Å. Sn is bonded to six equivalent Pd atoms to form SnPd6 octahedra that share faces with eight equivalent CePd12 cuboctahedra.

36 MATERIALS SCIENCE↗
DOE OSTI2025

Galactic Chemical Evolution of Short-lived Radioactive Isotopes Produced by Explosive Nucleosynthesis: 60 Fe and 53 Mn

Several short-lived radionuclides (SLRs) are know to have existed in the early solar system (ESS). These species, which typically decay with half-lives of the order of a few million years, can be used to probe the timescales of events preceding the birth of the Sun. We investigate the ESS origin of 53 Mn, produced by core-collapse supernovae (CCSNe) and Type Ia supernovae (SNe Ia), and 60 Fe, produced exclusively by CCSNe. We model the evolution of the radioactive-to-stable abundance ratios of these SLRs with a Galactic chemical evolution (GCE) framework accounting for different SN yields, SN Ia delay times, and other Galactic features (K). A further set of models is calculated assuming that SNe Ia did not contribute any 53 Mn to the ESS. The predicted ratios are compared to meteoritic ratios to derive a distribution of solar isolation times that includes uncertainties due to stochastic chemical enrichment and measurements of the ESS values. The isolation times are then compared to those of 107 Pd and 182 Hf calculated in previous work. A self-consistent solution can be found within the current uncertainties, especially when using the GCE setups with K = 1.6 and 2.3, although the maximum likelihood for the 60 Fe distribution is typically ∼4–5 Myr shorter than for 53 Mn. The predicted 60 Fe/ 53 Mn ratio, instead, is completely inconsistent with the ESS value; this could be resolved using a larger fraction of faint CCSNe than usually considered in GCE models.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2020

Evolution of collectivity in 118 Xe

A recoil-distance Doppler shift experiment has been performed using the Pd 102 ( F 19 , p 2 n ) reaction at a beam energy of 73 MeV to measure the lifetime of excited states in Xe 118 . Additionally, the differential decay-curve method using γ γ coincidences and a gating procedure that allows to extract the lifetime without feeding assumptions has been employed. The lifetimes obtained for the yrast states up to spin-parity 8 + are compared with interacting boson model calculations and Xe 118 can be classified as a transitional nucleus between the spherical and a deformed shape. Systematics of the B ( E 2 ) values for the 2 + → 0 + and 4 + → 2 + transitions in the isotopic chains of tin, tellurium and xenon are presented. It is proposed that a “critical point” exists at which the B ( E 2 ; 4 + → 2 + ) / B ( E 2 ; 2 + → 0 + ) ratio drops to unity for lower neutron numbers within the isotopic chain. The position of the “critical point” varies with proton number, i.e., it is presumed to be located at the same mass number A = 114 in the Sn, Te, and Xe isotopes.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗