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At least 883 records · Page 49
All sourcesNASA NTRSDOE OSTI
DOE OSTI2020

Materials Data on Os(CO)4 by Materials Project

Os(CO)4 crystallizes in the monoclinic P2_1/c space group. The structure is zero-dimensional and consists of twelve Os(CO)4 clusters. In four of the Os(CO)4 clusters, Os2- is bonded in a see-saw-like geometry to four C+2.50+ atoms. There is two shorter (1.91 Å) and two longer (1.96 Å) Os–C bond length. There are four inequivalent C+2.50+ sites. In the first C+2.50+ site, C+2.50+ is bonded in a distorted linear geometry to one Os2- and one O2- atom. The C–O bond length is 1.16 Å. In the second C+2.50+ site, C+2.50+ is bonded in a linear geometry to one Os2- and one O2- atom. The C–O bond length is 1.16 Å. In the third C+2.50+ site, C+2.50+ is bonded in a distorted linear geometry to one Os2- and one O2- atom. The C–O bond length is 1.16 Å. In the fourth C+2.50+ site, C+2.50+ is bonded in a distorted linear geometry to one Os2- and one O2- atom. The C–O bond length is 1.16 Å. There are four inequivalent O2- sites. In the first O2- site, O2- is bonded in a single-bond geometry to one C+2.50+ atom. In the second O2- site, O2- is bonded in a single-bond geometry to one C+2.50+ atom. In the third O2- site, O2- is bonded in a single-bond geometry to one C+2.50+ atom. In the fourth O2- site, O2- is bonded in a single-bond geometry to one C+2.50+ atom. In eight of the Os(CO)4 clusters, Os2- is bonded in a see-saw-like geometry to four C+2.50+ atoms. There are a spread of Os–C bond distances ranging from 1.90–1.96 Å. There are four inequivalent C+2.50+ sites. In the first C+2.50+ site, C+2.50+ is bonded in a linear geometry to one Os2- and one O2- atom. The C–O bond length is 1.16 Å. In the second C+2.50+ site, C+2.50+ is bonded in a distorted linear geometry to one Os2- and one O2- atom. The C–O bond length is 1.16 Å. In the third C+2.50+ site, C+2.50+ is bonded in a distorted linear geometry to one Os2- and one O2- atom. The C–O bond length is 1.16 Å. In the fourth C+2.50+ site, C+2.50+ is bonded in a linear geometry to one Os2- and one O2- atom. The C–O bond length is 1.16 Å. There are four inequivalent O2- sites. In the first O2- site, O2- is bonded in a single-bond geometry to one C+2.50+ atom. In the second O2- site, O2- is bonded in a single-bond geometry to one C+2.50+ atom. In the third O2- site, O2- is bonded in a single-bond geometry to one C+2.50+ atom. In the fourth O2- site, O2- is bonded in a single-bond geometry to one C+2.50+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on H12OsSN4O7 by Materials Project

(OsH12(N2O)2)2(SO4)2O2 crystallizes in the monoclinic P2_1/c space group. The structure is zero-dimensional and consists of four sulfuric acid molecules, four water molecules, and four OsH12(N2O)2 clusters. In two of the OsH12(N2O)2 clusters, Os8+ is bonded in an octahedral geometry to four N1- and two equivalent O2- atoms. All Os–N bond lengths are 2.14 Å. Both Os–O bond lengths are 1.75 Å. There are two inequivalent N1- sites. In the first N1- site, N1- is bonded in a trigonal non-coplanar geometry to one Os8+ and three H1+ atoms. There is one shorter (1.03 Å) and two longer (1.04 Å) N–H bond length. In the second N1- site, N1- is bonded in a trigonal non-coplanar geometry to one Os8+ and three H1+ atoms. There is two shorter (1.03 Å) and one longer (1.04 Å) N–H bond length. There are six inequivalent H1+ sites. In the first H1+ site, H1+ is bonded in a single-bond geometry to one N1- atom. In the second H1+ site, H1+ is bonded in a single-bond geometry to one N1- atom. In the third H1+ site, H1+ is bonded in a single-bond geometry to one N1- atom. In the fourth H1+ site, H1+ is bonded in a single-bond geometry to one N1- atom. In the fifth H1+ site, H1+ is bonded in a single-bond geometry to one N1- atom. In the sixth H1+ site, H1+ is bonded in a single-bond geometry to one N1- atom. O2- is bonded in a single-bond geometry to one Os8+ atom. In two of the OsH12(N2O)2 clusters, Os8+ is bonded in an octahedral geometry to four N1- and two equivalent O2- atoms. All Os–N bond lengths are 2.14 Å. Both Os–O bond lengths are 1.75 Å. There are two inequivalent N1- sites. In the first N1- site, N1- is bonded in a trigonal non-coplanar geometry to one Os8+ and three H1+ atoms. There is two shorter (1.03 Å) and one longer (1.04 Å) N–H bond length. In the second N1- site, N1- is bonded in a trigonal non-coplanar geometry to one Os8+ and three H1+ atoms. There is two shorter (1.03 Å) and one longer (1.04 Å) N–H bond length. There are six inequivalent H1+ sites. In the first H1+ site, H1+ is bonded in a single-bond geometry to one N1- atom. In the second H1+ site, H1+ is bonded in a single-bond geometry to one N1- atom. In the third H1+ site, H1+ is bonded in a single-bond geometry to one N1- atom. In the fourth H1+ site, H1+ is bonded in a single-bond geometry to one N1- atom. In the fifth H1+ site, H1+ is bonded in a single-bond geometry to one N1- atom. In the sixth H1+ site, H1+ is bonded in a single-bond geometry to one N1- atom. O2- is bonded in a single-bond geometry to one Os8+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on KB6H4(OF3)2 by Materials Project

KB4H4(OF2)2(FB1)2 crystallizes in the triclinic P-1 space group. The structure is zero-dimensional and consists of eight boron monofluoride molecules and two KB4H4(OF2)2 clusters. In one of the KB4H4(OF2)2 clusters, K is bonded in a 7-coordinate geometry to three O and four F atoms. There are a spread of K–O bond distances ranging from 2.71–2.92 Å. There are a spread of K–F bond distances ranging from 2.69–3.02 Å. There are four inequivalent B sites. In the first B site, B is bonded in a single-bond geometry to one F atom. The B–F bond length is 1.40 Å. In the second B site, B is bonded in a single-bond geometry to one F atom. The B–F bond length is 1.40 Å. In the third B site, B is bonded in a single-bond geometry to one F atom. The B–F bond length is 1.39 Å. In the fourth B site, B is bonded in a single-bond geometry to one F atom. The B–F bond length is 1.39 Å. There are four inequivalent H sites. In the first H site, H is bonded in a single-bond geometry to one O atom. The H–O bond length is 0.99 Å. In the second H site, H is bonded in a single-bond geometry to one O atom. The H–O bond length is 0.98 Å. In the third H site, H is bonded in a single-bond geometry to one O atom. The H–O bond length is 0.98 Å. In the fourth H site, H is bonded in a single-bond geometry to one O atom. The H–O bond length is 0.97 Å. There are two inequivalent O sites. In the first O site, O is bonded in a water-like geometry to one K and two H atoms. In the second O site, O is bonded in a water-like geometry to two equivalent K and two H atoms. There are four inequivalent F sites. In the first F site, F is bonded in a single-bond geometry to one K and one B atom. In the second F site, F is bonded in a distorted single-bond geometry to one K and one B atom. In the third F site, F is bonded in a distorted single-bond geometry to one K and one B atom. In the fourth F site, F is bonded in a single-bond geometry to one K and one B atom. In one of the KB4H4(OF2)2 clusters, K is bonded in a 7-coordinate geometry to three O and four F atoms. There are a spread of K–O bond distances ranging from 2.77–2.86 Å. There are a spread of K–F bond distances ranging from 2.82–3.19 Å. There are four inequivalent B sites. In the first B site, B is bonded in a single-bond geometry to one F atom. The B–F bond length is 1.40 Å. In the second B site, B is bonded in a single-bond geometry to one F atom. The B–F bond length is 1.40 Å. In the third B site, B is bonded in a single-bond geometry to one F atom. The B–F bond length is 1.41 Å. In the fourth B site, B is bonded in a single-bond geometry to one F atom. The B–F bond length is 1.40 Å. There are four inequivalent H sites. In the first H site, H is bonded in a single-bond geometry to one O atom. The H–O bond length is 0.99 Å. In the second H site, H is bonded in a single-bond geometry to one O atom. The H–O bond length is 0.98 Å. In the third H site, H is bonded in a single-bond geometry to one O atom. The H–O bond length is 0.98 Å. In the fourth H site, H is bonded in a single-bond geometry to one O atom. The H–O bond length is 0.98 Å. There are two inequivalent O sites. In the first O site, O is bonded in a distorted water-like geometry to two equivalent K and two H atoms. In the second O site, O is bonded in a water-like geometry to one K and two H atoms. There are four inequivalent F sites. In the first F site, F is bonded in a distorted single-bond geometry to one K and one B atom. In the second F site, F is bonded in a single-bond geometry to one K and one B atom. In the third F site, F is bonded in a single-bond geometry to one K and one B atom. In the fourth F site, F is bonded in a distorted single-bond geometry to one K and one B atom.

36 MATERIALS SCIENCE↗
DOE OSTI2025

Towards a multiscale approach for understanding irradiation induced swelling and creep in 316 stainless steels - A coupled cluster dynamics and crystal plasticity approach

Structural materials undergo mechanical degradation, in part due to irradiation-induced swelling and creep, under nuclear reactor conditions. While swelling results from the migration and clustering of irradiation-induced atomic-scale mobile defects, the interaction of mesoscale dislocations with these defects causes creep deformation. A coupled crystal plasticity (CP) and mean-field cluster dynamics (CD) approach is presented to investigate the effect of irradiation on the long-term mechanical behavior of 316 stainless steel, which are under consideration for use in nuclear reactors. The temporal evolution of Frenkel pairs and extended defect population, under a chosen irradiation flux and temperature, is predicted using the CD model. The impact of the irradiation defects on the stress state, and the resulting dislocation-mediated inelastic deformation, is modeled concurrently with the CP model. The inelastic deformation is irradiation flux dependent, and early-stage defect evolution determines the later-stage mechanical behavior in 316 stainless steel.

36 - MATERIALS SCIENCE↗
DOE OSTI2024

Bottom-up design of actinide materials from molecular clusters: Demonstration of a general-purpose simulation capability leveraging machine-learned atomic potentials

Actinide thin-film coatings such as uranium dioxide (UO 2 ) play an important role in nuclear reactors and other mission-relevant applications, but realization of their potential requires a deep fundamental understanding of the chemical vapor deposition (CVD) processes used for their growth. The slow experimental progress can be attributed, in part, to the standard safety guidelines associated with handling uranium byproducts, which are often corrosive, toxic, and radioactive. Accurate simulation techniques, when used in concert with experiment, can improve laboratory safety, material durability, and deliverable timeframes. However, state-of-the-art computational methods are either insufficiently accurate or intractably expensive. To remedy this situation, in this project we suggested a machine-learning (ML) accelerated workflow for simulating molecular clustering toward deposition. As a benchmark test case, we considered molecular clustering in steam and assessed independent components of our workflow by comparing with measured thermodynamic properties of water. After analyzing each component individually and finding no fundamental barrier to realization of the workflow, we attempted to integrate the ML component, a Sandia-developed tool called FitSNAP. As this was the first application of FitSNAP to atoms and molecules in the gas phase at Sandia, the method required more fitting data than was originally anticipated. Systematic improvements were made by including in the fit data diatomic potentials, molecular single-bond-breaking curves, and symmetry-constrained intermolecular potentials. We concluded that our strategy provides a feasible pathway toward modeling CVD and related processes, but that extensive training data must be generated before it can be of practical use.

36 MATERIALS SCIENCE↗
DOE OSTI2023

Probing the Potential Energy Profile of the I + (H 2 O) 3 → HI + (H 2 O) 2 OH Forward and Reverse Reactions: High Level CCSD(T) Studies with Spin-Orbit Coupling Included

Three different pathways for the atomic iodine plus water trimer reaction I + (H 2 O) 3 → HI + (H 2 O) 2 OH were preliminarily examined by the DFT-MPW1K method. Related to previous predictions for the F/Cl/Br + (H 2 O) 3 reactions, three pathways for the I + (H 2 O) 3 reaction are linked in terms of geometry and energetics. To legitimize the results, the “gold standard” CCSD(T) method was employed to investigate the lowest-lying pathway with the correlation-consistent polarized valence basis set up to cc-pVQZ(-PP). According to the CCSD(T)/cc-pVQZ(-PP)//CCSD(T)/cc-pVTZ(-PP) results, the I + (H 2 O) 3 → HI + (H 2 O) 2 OH reaction is predicted to be endothermic by 47.0 kcal mol -1 . The submerged transition state is predicted to lie 43.7 kcal mol -1 above the separated reactants. The I···(H 2 O) 3 entrance complex lies below the separated reactants by 4.1 kcal mol -1 , and spin-orbit coupling has a significant impact on this dissociation energy. The HI···(H 2 O) 2 OH exit complex is bound by 4.3 kcal mol -1 in relation to the separated products. Compared with simpler I + (H 2 O) 2 and I + H 2 O reactions, the I + (H 2 O) 3 reaction is energetically between them in general. It is speculated that the reaction between the iodine atom and the larger water clusters may be energetically analogous to the I + (H 2 O) 3 reaction. The iodine reaction I + (H 2 O) 3 is connected with the analogous valence isoelectronic bromine/chlorine reactions Br/Cl + (H 2 O) 3 but much different from the F + (H 2 O) 3 reaction. Significant difference with other halogen systems, especially for barrier heights, are seen for the iodine systems.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
NASA NTRS1982

Theoretical studies of the electronic structure of small metal clusters

Theoretical studies of the electronic structure of metal clusters, in particular clusters of Group IIA and IIB atoms were conducted. Early in the project it became clear that electron correlation involving d orbitals plays a more important role in the binding of these clusters than had been previously anticipated. This necessitated that computer codes for calculating two electron integrals and for constructing the resulting CI Hamiltonions be replaced with newer, more efficient procedures. Program modification, interfacing and testing were performed. Results of both plans are reported.

Jordan, K. D.↗
DOE OSTI2020

Materials Data on CS2(NCl)3 by Materials Project

CS2(NCl)3 crystallizes in the triclinic P-1 space group. The structure is zero-dimensional and consists of four CS2(NCl)3 clusters. In two of the CS2(NCl)3 clusters, C4+ is bonded in a distorted trigonal planar geometry to two N1+ and one Cl1- atom. Both C–N bond lengths are 1.33 Å. The C–Cl bond length is 1.73 Å. There are three inequivalent N1+ sites. In the first N1+ site, N1+ is bonded in a bent 120 degrees geometry to two S2- atoms. There is one shorter (1.61 Å) and one longer (1.62 Å) N–S bond length. In the second N1+ site, N1+ is bonded in a distorted bent 120 degrees geometry to one C4+ and one S2- atom. The N–S bond length is 1.62 Å. In the third N1+ site, N1+ is bonded in a distorted bent 120 degrees geometry to one C4+ and one S2- atom. The N–S bond length is 1.62 Å. There are two inequivalent S2- sites. In the first S2- site, S2- is bonded in a trigonal non-coplanar geometry to two N1+ and one Cl1- atom. The S–Cl bond length is 2.15 Å. In the second S2- site, S2- is bonded in a trigonal non-coplanar geometry to two N1+ and one Cl1- atom. The S–Cl bond length is 2.17 Å. There are three inequivalent Cl1- sites. In the first Cl1- site, Cl1- is bonded in a single-bond geometry to one C4+ atom. In the second Cl1- site, Cl1- is bonded in a single-bond geometry to one S2- atom. In the third Cl1- site, Cl1- is bonded in a single-bond geometry to one S2- atom. In two of the CS2(NCl)3 clusters, C4+ is bonded in a distorted trigonal planar geometry to two N1+ and one Cl1- atom. Both C–N bond lengths are 1.33 Å. The C–Cl bond length is 1.72 Å. There are three inequivalent N1+ sites. In the first N1+ site, N1+ is bonded in a distorted bent 120 degrees geometry to one C4+ and one S2- atom. The N–S bond length is 1.61 Å. In the second N1+ site, N1+ is bonded in a distorted bent 120 degrees geometry to one C4+ and one S2- atom. The N–S bond length is 1.62 Å. In the third N1+ site, N1+ is bonded in a bent 120 degrees geometry to two S2- atoms. There is one shorter (1.61 Å) and one longer (1.63 Å) N–S bond length. There are two inequivalent S2- sites. In the first S2- site, S2- is bonded in a distorted trigonal non-coplanar geometry to two N1+ and one Cl1- atom. The S–Cl bond length is 2.19 Å. In the second S2- site, S2- is bonded in a trigonal non-coplanar geometry to two N1+ and one Cl1- atom. The S–Cl bond length is 2.15 Å. There are three inequivalent Cl1- sites. In the first Cl1- site, Cl1- is bonded in a single-bond geometry to one S2- atom. In the second Cl1- site, Cl1- is bonded in a single-bond geometry to one S2- atom. In the third Cl1- site, Cl1- is bonded in a single-bond geometry to one C4+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Os(CO)4 by Materials Project

Os(CO)4 crystallizes in the triclinic P-1 space group. The structure is zero-dimensional and consists of eight Os(CO)4 clusters. In four of the Os(CO)4 clusters, Os2- is bonded in a rectangular see-saw-like geometry to four C+2.50+ atoms. There are a spread of Os–C bond distances ranging from 1.91–1.96 Å. There are four inequivalent C+2.50+ sites. In the first C+2.50+ site, C+2.50+ is bonded in a distorted linear geometry to one Os2- and one O2- atom. The C–O bond length is 1.16 Å. In the second C+2.50+ site, C+2.50+ is bonded in a linear geometry to one Os2- and one O2- atom. The C–O bond length is 1.17 Å. In the third C+2.50+ site, C+2.50+ is bonded in a distorted linear geometry to one Os2- and one O2- atom. The C–O bond length is 1.16 Å. In the fourth C+2.50+ site, C+2.50+ is bonded in a distorted linear geometry to one Os2- and one O2- atom. The C–O bond length is 1.16 Å. There are four inequivalent O2- sites. In the first O2- site, O2- is bonded in a single-bond geometry to one C+2.50+ atom. In the second O2- site, O2- is bonded in a single-bond geometry to one C+2.50+ atom. In the third O2- site, O2- is bonded in a single-bond geometry to one C+2.50+ atom. In the fourth O2- site, O2- is bonded in a single-bond geometry to one C+2.50+ atom. In four of the Os(CO)4 clusters, Os2- is bonded in a rectangular see-saw-like geometry to four C+2.50+ atoms. There are a spread of Os–C bond distances ranging from 1.90–1.96 Å. There are four inequivalent C+2.50+ sites. In the first C+2.50+ site, C+2.50+ is bonded in a linear geometry to one Os2- and one O2- atom. The C–O bond length is 1.16 Å. In the second C+2.50+ site, C+2.50+ is bonded in a distorted linear geometry to one Os2- and one O2- atom. The C–O bond length is 1.16 Å. In the third C+2.50+ site, C+2.50+ is bonded in a distorted linear geometry to one Os2- and one O2- atom. The C–O bond length is 1.16 Å. In the fourth C+2.50+ site, C+2.50+ is bonded in a distorted linear geometry to one Os2- and one O2- atom. The C–O bond length is 1.16 Å. There are four inequivalent O2- sites. In the first O2- site, O2- is bonded in a single-bond geometry to one C+2.50+ atom. In the second O2- site, O2- is bonded in a single-bond geometry to one C+2.50+ atom. In the third O2- site, O2- is bonded in a single-bond geometry to one C+2.50+ atom. In the fourth O2- site, O2- is bonded in a single-bond geometry to one C+2.50+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on MnPH2(CO)4 by Materials Project

Mn(CO)4PH2 crystallizes in the monoclinic P2/c space group. The structure is zero-dimensional and consists of six phosphine molecules and six Mn(CO)4 clusters. In two of the Mn(CO)4 clusters, Mn2+ is bonded in a rectangular see-saw-like geometry to four C+0.25- atoms. There is two shorter (1.82 Å) and two longer (1.86 Å) Mn–C bond length. There are two inequivalent C+0.25- sites. In the first C+0.25- site, C+0.25- is bonded in a linear geometry to one Mn2+ and one O2- atom. The C–O bond length is 1.16 Å. In the second C+0.25- site, C+0.25- is bonded in a linear geometry to one Mn2+ and one O2- atom. The C–O bond length is 1.16 Å. There are two inequivalent O2- sites. In the first O2- site, O2- is bonded in a single-bond geometry to one C+0.25- atom. In the second O2- site, O2- is bonded in a single-bond geometry to one C+0.25- atom. In four of the Mn(CO)4 clusters, Mn2+ is bonded in a rectangular see-saw-like geometry to four C+0.25- atoms. There are a spread of Mn–C bond distances ranging from 1.82–1.86 Å. There are four inequivalent C+0.25- sites. In the first C+0.25- site, C+0.25- is bonded in a linear geometry to one Mn2+ and one O2- atom. The C–O bond length is 1.16 Å. In the second C+0.25- site, C+0.25- is bonded in a linear geometry to one Mn2+ and one O2- atom. The C–O bond length is 1.16 Å. In the third C+0.25- site, C+0.25- is bonded in a linear geometry to one Mn2+ and one O2- atom. The C–O bond length is 1.16 Å. In the fourth C+0.25- site, C+0.25- is bonded in a linear geometry to one Mn2+ and one O2- atom. The C–O bond length is 1.16 Å. There are four inequivalent O2- sites. In the first O2- site, O2- is bonded in a single-bond geometry to one C+0.25- atom. In the second O2- site, O2- is bonded in a single-bond geometry to one C+0.25- atom. In the third O2- site, O2- is bonded in a single-bond geometry to one C+0.25- atom. In the fourth O2- site, O2- is bonded in a single-bond geometry to one C+0.25- atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on FeC7(O2F)2 by Materials Project

Fe(CO)4C(CF)2 crystallizes in the monoclinic P2_1/c space group. The structure is zero-dimensional and consists of sixteen fluoromethane molecules, eight methane molecules, and eight Fe(CO)4 clusters. In four of the Fe(CO)4 clusters, Fe3+ is bonded in a distorted rectangular see-saw-like geometry to four C1+ atoms. There is one shorter (1.80 Å) and three longer (1.82 Å) Fe–C bond length. There are four inequivalent C1+ sites. In the first C1+ site, C1+ is bonded in a distorted linear geometry to one Fe3+ and one O2- atom. The C–O bond length is 1.15 Å. In the second C1+ site, C1+ is bonded in a distorted single-bond geometry to one Fe3+ and one O2- atom. The C–O bond length is 1.15 Å. In the third C1+ site, C1+ is bonded in a distorted single-bond geometry to one Fe3+ and one O2- atom. The C–O bond length is 1.15 Å. In the fourth C1+ site, C1+ is bonded in a distorted single-bond geometry to one Fe3+ and one O2- atom. The C–O bond length is 1.16 Å. There are four inequivalent O2- sites. In the first O2- site, O2- is bonded in a single-bond geometry to one C1+ atom. In the second O2- site, O2- is bonded in a single-bond geometry to one C1+ atom. In the third O2- site, O2- is bonded in a single-bond geometry to one C1+ atom. In the fourth O2- site, O2- is bonded in a single-bond geometry to one C1+ atom. In four of the Fe(CO)4 clusters, Fe3+ is bonded in a distorted rectangular see-saw-like geometry to four C1+ atoms. There is one shorter (1.80 Å) and three longer (1.82 Å) Fe–C bond length. There are four inequivalent C1+ sites. In the first C1+ site, C1+ is bonded in a distorted linear geometry to one Fe3+ and one O2- atom. The C–O bond length is 1.15 Å. In the second C1+ site, C1+ is bonded in a distorted single-bond geometry to one Fe3+ and one O2- atom. The C–O bond length is 1.15 Å. In the third C1+ site, C1+ is bonded in a distorted single-bond geometry to one Fe3+ and one O2- atom. The C–O bond length is 1.15 Å. In the fourth C1+ site, C1+ is bonded in a distorted single-bond geometry to one Fe3+ and one O2- atom. The C–O bond length is 1.16 Å. There are four inequivalent O2- sites. In the first O2- site, O2- is bonded in a single-bond geometry to one C1+ atom. In the second O2- site, O2- is bonded in a single-bond geometry to one C1+ atom. In the third O2- site, O2- is bonded in a single-bond geometry to one C1+ atom. In the fourth O2- site, O2- is bonded in a single-bond geometry to one C1+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2024

Effect of Hydrogen and Helium on Irradiation Damage Accumulation in Nickel

We report our results on the study of the effects of hydrogen and helium on irradiation damage accumulation in nickel, aiming to understand the TEM observations made by Edwards et al. regarding the Ni-coatings protecting the getter tube in a TPBAR. We hypothesized that differences in the fluxes of 3 H and/or He between the coatings might explain these microstructural variations. However, our simulation results show that during the initial stages of irradiation, the presence of H or He enhances void nucleation by stabilizing small vacancy clusters against thermal dissociation and does not enhance void growth. Nevertheless, we think that helium’s higher diffusivity, stronger binding with vacancy clusters, and ability to displace a nearby lattice atom—either to create a new vacancy or to enlarge an existing vacancy cluster—could result in a larger average vacancy cluster size. Therefore, it is likely that void growth will occur post-nucleation phase as more He accumulates at higher doses than those simulated in this study.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Synthesis of Co‐Doped MoS 2 Monolayers with Enhanced Valley Splitting

Abstract Internal magnetic moments induced by magnetic dopants in MoS 2 monolayers are shown to serve as a new means to engineer valley Zeeman splitting (VZS). Specifically, successful synthesis of monolayer MoS 2 doped with the magnetic element Co is reported, and the magnitude of the valley splitting is engineered by manipulating the dopant concentration. Valley splittings of 3.9, 5.2, and 6.15 meV at 7 T in Co‐doped MoS 2 with Co concentrations of 0.8%, 1.7%, and 2.5%, respectively, are achieved as revealed by polarization‐resolved photoluminescence (PL) spectroscopy. Atomic‐resolution electron microscopy studies clearly identify the magnetic sites of Co substitution in the MoS 2 lattice, forming two distinct types of configurations, namely isolated single dopants and tridopant clusters. Density functional theory (DFT) and model calculations reveal that the observed enhanced VZS arises from an internal magnetic field induced by the tridopant clusters, which couples to the spin, atomic orbital, and valley magnetic moment of carriers from the conduction and valence bands. The present study demonstrates a new method to control the valley pseudospin via magnetic dopants in layered semiconducting materials, paving the way toward magneto‐optical and spintronic devices.

Zhou, Jiadong↗
DOE OSTI2022

Gas-phase fragmentation of single heteroatom-incorporated Co 5 MS 8 (PEt 3 ) 6 + (M = Mn, Fe, Co, Ni) nanoclusters

Functionalization of metal-chalcogenide clusters by either replacing core atoms or by tuning the ligand is a powerful technique to tailor their properties. Central to this approach is understanding the competition between the strength of the metal-ligand and metal-metal interactions. Here, using collision-induced dissociation of atomically precise metal sulfide nanoclusters, Co 5 MS 8 L 6 + (L = PEt 3 , M = Mn, Fe, Co, Ni) and Co 5-x Fe x S 8 L 6 + (x = 1–3), we study the effect of a heteroatom incorporation on the core-ligand interactions and relative stability towards fragmentation. Sequential ligand loss is the dominant dissociation pathway that competes with ligand sulfide (LS) loss. Because the ligands are attached to metal atoms, LS loss is an unusual dissociation pathway, indicating significant rearrangement of the core prior to fragmentation. Both experiments and theoretical calculations indicate the reduced stability of Co 5 MnS 8 L 6 + and Co 5 FeS 8 L 6 + towards the first ligand loss in comparison with their Co 6 S 8 L 6 + and Co 5 NiS 8 L 6 + counterparts and provide insights into the core-ligand interaction.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2025

Resolving the Solvation Structure and Transport Properties of Aqueous Zinc Electrolytes from Salt-in-Water to Water-in-Salt Using Neural Network Potential

Zn Cl 2 solutions are promising electrolytes for aqueous zinc-ion batteries. Here, we report a joint computational and experimental study of the structural and dynamic properties of aqueous Zn Cl 2 electrolytes with concentrations ranging from salt-in-water to water-in-salt (WIS). By developing a neural network potential (NNP) model, we perform molecular dynamics (MD) simulations with accuracy but at much larger lengths and longer timescales. The NNP predicted structures are validated by the structure factors measured by X-ray total scattering experiments. The MD trajectories provide a comprehensive and quantitative picture of the Zn 2 + solvation shell structures. Additionally, we find that the O − H covalent bonds in water are strengthened with increasing salt concentration, thus expanding the electrochemical stability window of aqueous electrolytes. In terms of dynamic properties, the calculated and experimentally measured conductivities are in good agreement. Through the analysis of the calculated cation transference number, we propose a three-stage charge carrier transport mechanism with increasing concentration: independent ion transport, strongly correlated ion transport, and small positive charge carrier diffusion through negatively charged polymeric clusters. Our study provides fundamental atomic scale insights into the structure and transport properties of the Zn Cl 2 electrolyte that can aid the optimization and development of WIS electrolytes. Published by the American Physical Society 2025

25 ENERGY STORAGE↗
NASA NTRS1987

Small Al clusters. II - Structure and binding in Al(n) (n = 2-6, 13)

The structure and stability of aluminum clusters containing up to six atoms have been studied using correlated wave functions and extended basis sets. The lowest energy structure is planar for Al4 and Al5, but three dimensional for Al6. The icosahedral, hcp, fcc, and two planar structures of Al13 were considered at the SCF level. The lowest energy structure is the icosahedron, but the planar structures are fairly low lying even in this case. A simplified description using two- and three-body interaction potentials is found to agree well with the ab initio structures and binding energies.

Pettersson, Lars G. M.↗
NASA NTRS1993

Infrared spectra of transition objects and the composition and evolution of carbon dust

We obtained IR (5-23 microns) spectra of five carbon-rich objects in transition from the asymptotic giant branch (AGB) to the planetary nebula stage of evolution. These spectra show a variety of IR emission features due to circumstellar materials. In particular, all sources show the 6.2 and '7.7' micron bands, commonly observed in PNs and ascribed to polycyclic aromatic hydrocarbon molecules (PAHs). Some transition nebulae also show a strong 6-9 micron plateau characteristic for larger PAH clusters (about 400 C-atoms). A new broad feature at about 8.8 microns is present in some sources. This feature is distinctly different from the 8.6-micron PAH feature. This 8.8-micron feature may be present in the spectra of C-rich giants as well, but is not evident in PN spectra. We suggest that large amorphous carbon grains are responsible for the 8.8-micron feature. The transition objects show large spectral variations from source to source. This contrasts with C-rich PNs, which all show very similar IR spectra dominated by PAHs. These spectral variations between transition objects of similar effective temperatures cannot be due to excitation variations but imply compositional variations of the dust. Moreover, this result suggests that circumstellar dust evolves during the transition phase from red giant to PN, perhaps as a result of grain-grain collisions and shattering in the fast winds.

Buss, R. H., Jr.↗