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At least 1,189 records · Page 66
All sourcesNASA NTRSDOE OSTI
DOE OSTI2020

Materials Data on Y2AlCo3 by Materials Project

Y2Co3Al crystallizes in the trigonal R-3m space group. The structure is three-dimensional. Y is bonded in a 9-coordinate geometry to four equivalent Y, nine equivalent Co, and three equivalent Al atoms. There are one shorter (3.02 Å) and three longer (3.22 Å) Y–Y bond lengths. There are three shorter (2.86 Å) and six longer (3.08 Å) Y–Co bond lengths. All Y–Al bond lengths are 3.13 Å. Co is bonded to six equivalent Y, four equivalent Co, and two equivalent Al atoms to form distorted CoY6Al2Co4 cuboctahedra that share corners with four equivalent AlY6Co6 cuboctahedra, corners with fourteen equivalent CoY6Al2Co4 cuboctahedra, edges with six equivalent CoY6Al2Co4 cuboctahedra, faces with six equivalent AlY6Co6 cuboctahedra, and faces with twelve equivalent CoY6Al2Co4 cuboctahedra. All Co–Co bond lengths are 2.68 Å. Both Co–Al bond lengths are 2.49 Å. Al is bonded to six equivalent Y and six equivalent Co atoms to form distorted AlY6Co6 cuboctahedra that share corners with six equivalent AlY6Co6 cuboctahedra, corners with twelve equivalent CoY6Al2Co4 cuboctahedra, edges with six equivalent AlY6Co6 cuboctahedra, and faces with eighteen equivalent CoY6Al2Co4 cuboctahedra.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on YMg3 by Materials Project

YMg3 is beta-derived structured and crystallizes in the orthorhombic Imm2 space group. The structure is three-dimensional. there are two inequivalent Mg sites. In the first Mg site, Mg is bonded to eight Mg and four equivalent Y atoms to form MgY4Mg8 cuboctahedra that share corners with four equivalent YY2Mg10 cuboctahedra, corners with fourteen equivalent MgY4Mg8 cuboctahedra, edges with four equivalent YY2Mg10 cuboctahedra, edges with fourteen MgY4Mg8 cuboctahedra, faces with six equivalent YY2Mg10 cuboctahedra, and faces with fourteen MgY4Mg8 cuboctahedra. There are a spread of Mg–Mg bond distances ranging from 3.28–3.37 Å. There are two shorter (3.28 Å) and two longer (3.34 Å) Mg–Y bond lengths. In the second Mg site, Mg is bonded to nine Mg and three equivalent Y atoms to form MgY3Mg9 cuboctahedra that share corners with eighteen equivalent MgY3Mg9 cuboctahedra, edges with six equivalent YY2Mg10 cuboctahedra, edges with twelve MgY4Mg8 cuboctahedra, faces with six equivalent YY2Mg10 cuboctahedra, and faces with fourteen MgY4Mg8 cuboctahedra. There are two shorter (3.28 Å) and four longer (3.31 Å) Mg–Mg bond lengths. There are one shorter (3.34 Å) and two longer (3.36 Å) Mg–Y bond lengths. Y is bonded to ten Mg and two equivalent Y atoms to form YY2Mg10 cuboctahedra that share corners with four equivalent MgY4Mg8 cuboctahedra, corners with fourteen equivalent YY2Mg10 cuboctahedra, edges with two equivalent YY2Mg10 cuboctahedra, edges with sixteen MgY4Mg8 cuboctahedra, faces with two equivalent YY2Mg10 cuboctahedra, and faces with eighteen MgY4Mg8 cuboctahedra. Both Y–Y bond lengths are 3.28 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Y2Pt by Materials Project

PtY2 is Cotunnite structured and crystallizes in the orthorhombic Pnma space group. The structure is three-dimensional. there are two inequivalent Y sites. In the first Y site, Y is bonded to four equivalent Pt atoms to form a mixture of edge and corner-sharing YPt4 tetrahedra. There are a spread of Y–Pt bond distances ranging from 2.91–2.96 Å. In the second Y site, Y is bonded in a 3-coordinate geometry to three equivalent Pt atoms. There are one shorter (2.84 Å) and two longer (3.08 Å) Y–Pt bond lengths. Pt is bonded in a 7-coordinate geometry to seven Y atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Y3(Al3Os)4 by Materials Project

Y3(OsAl3)4 crystallizes in the hexagonal P6_3/mmc space group. The structure is three-dimensional. Y is bonded in a 5-coordinate geometry to four equivalent Os and eleven Al atoms. All Y–Os bond lengths are 3.38 Å. There are a spread of Y–Al bond distances ranging from 2.96–3.22 Å. There are two inequivalent Os sites. In the first Os site, Os is bonded in a body-centered cubic geometry to eight Al atoms. There are two shorter (2.39 Å) and six longer (2.60 Å) Os–Al bond lengths. In the second Os site, Os is bonded in a 12-coordinate geometry to four equivalent Y and eight Al atoms. There are four shorter (2.56 Å) and four longer (2.69 Å) Os–Al bond lengths. There are four inequivalent Al sites. In the first Al site, Al is bonded in a 3-coordinate geometry to three equivalent Y and three equivalent Os atoms. In the second Al site, Al is bonded in a 3-coordinate geometry to three equivalent Y and three Os atoms. In the third Al site, Al is bonded in a 2-coordinate geometry to two equivalent Y and two equivalent Os atoms. In the fourth Al site, Al is bonded in a distorted linear geometry to three equivalent Y and two equivalent Os atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on YMg2 by Materials Project

Mg2Y is beta-derived structured and crystallizes in the monoclinic C2/m space group. The structure is three-dimensional. there are two inequivalent Mg sites. In the first Mg site, Mg is bonded to nine Mg and three equivalent Y atoms to form distorted MgY3Mg9 cuboctahedra that share corners with six equivalent YY4Mg8 cuboctahedra, corners with twelve MgY3Mg9 cuboctahedra, edges with seven equivalent YY4Mg8 cuboctahedra, edges with eleven MgY3Mg9 cuboctahedra, faces with seven equivalent YY4Mg8 cuboctahedra, and faces with thirteen MgY3Mg9 cuboctahedra. There are a spread of Mg–Mg bond distances ranging from 3.25–3.49 Å. There are one shorter (3.26 Å) and two longer (3.41 Å) Mg–Y bond lengths. In the second Mg site, Mg is bonded to seven Mg and five equivalent Y atoms to form distorted MgY5Mg7 cuboctahedra that share corners with six equivalent YY4Mg8 cuboctahedra, corners with twelve MgY3Mg9 cuboctahedra, edges with five equivalent YY4Mg8 cuboctahedra, edges with thirteen MgY3Mg9 cuboctahedra, faces with eight equivalent YY4Mg8 cuboctahedra, and faces with twelve MgY3Mg9 cuboctahedra. There are two shorter (3.31 Å) and one longer (3.47 Å) Mg–Mg bond lengths. There are a spread of Mg–Y bond distances ranging from 3.34–3.49 Å. Y is bonded to eight Mg and four equivalent Y atoms to form YY4Mg8 cuboctahedra that share corners with six equivalent YY4Mg8 cuboctahedra, corners with twelve MgY3Mg9 cuboctahedra, edges with six equivalent YY4Mg8 cuboctahedra, edges with twelve MgY3Mg9 cuboctahedra, faces with five equivalent YY4Mg8 cuboctahedra, and faces with fifteen MgY3Mg9 cuboctahedra. There are two shorter (3.31 Å) and two longer (3.42 Å) Y–Y bond lengths.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Ba3SrY8(CuO5)4 by Materials Project

Ba3SrY8(CuO5)4 crystallizes in the monoclinic Pm space group. The structure is three-dimensional. there are three inequivalent Ba2+ sites. In the first Ba2+ site, Ba2+ is bonded in a 11-coordinate geometry to eleven O2- atoms. There are a spread of Ba–O bond distances ranging from 2.64–3.30 Å. In the second Ba2+ site, Ba2+ is bonded in a 11-coordinate geometry to eleven O2- atoms. There are a spread of Ba–O bond distances ranging from 2.59–3.29 Å. In the third Ba2+ site, Ba2+ is bonded in a 11-coordinate geometry to eleven O2- atoms. There are a spread of Ba–O bond distances ranging from 2.63–3.30 Å. Sr2+ is bonded in a 1-coordinate geometry to nine O2- atoms. There are a spread of Sr–O bond distances ranging from 2.51–3.05 Å. There are eight inequivalent Y3+ sites. In the first Y3+ site, Y3+ is bonded to seven O2- atoms to form distorted YO7 pentagonal bipyramids that share corners with five CuO5 square pyramids, edges with five YO7 pentagonal bipyramids, an edgeedge with one CuO5 square pyramid, and a faceface with one YO7 pentagonal bipyramid. There are a spread of Y–O bond distances ranging from 2.29–2.39 Å. In the second Y3+ site, Y3+ is bonded to seven O2- atoms to form distorted YO7 pentagonal bipyramids that share corners with five CuO5 square pyramids, edges with five YO7 pentagonal bipyramids, an edgeedge with one CuO5 square pyramid, and a faceface with one YO7 pentagonal bipyramid. There are a spread of Y–O bond distances ranging from 2.28–2.40 Å. In the third Y3+ site, Y3+ is bonded to seven O2- atoms to form distorted YO7 pentagonal bipyramids that share corners with five CuO5 square pyramids, edges with five YO7 pentagonal bipyramids, an edgeedge with one CuO5 square pyramid, and a faceface with one YO7 pentagonal bipyramid. There are a spread of Y–O bond distances ranging from 2.28–2.38 Å. In the fourth Y3+ site, Y3+ is bonded to seven O2- atoms to form distorted YO7 pentagonal bipyramids that share corners with five CuO5 square pyramids, edges with five YO7 pentagonal bipyramids, an edgeedge with one CuO5 square pyramid, and a faceface with one YO7 pentagonal bipyramid. There are a spread of Y–O bond distances ranging from 2.29–2.40 Å. In the fifth Y3+ site, Y3+ is bonded to seven O2- atoms to form distorted YO7 pentagonal bipyramids that share corners with four equivalent YO7 pentagonal bipyramids, edges with three YO7 pentagonal bipyramids, edges with two equivalent CuO5 square pyramids, a faceface with one YO7 pentagonal bipyramid, and a faceface with one CuO5 square pyramid. There are a spread of Y–O bond distances ranging from 2.33–2.38 Å. In the sixth Y3+ site, Y3+ is bonded to seven O2- atoms to form distorted YO7 pentagonal bipyramids that share corners with four equivalent YO7 pentagonal bipyramids, edges with three YO7 pentagonal bipyramids, edges with two equivalent CuO5 square pyramids, a faceface with one YO7 pentagonal bipyramid, and a faceface with one CuO5 square pyramid. There are a spread of Y–O bond distances ranging from 2.30–2.38 Å. In the seventh Y3+ site, Y3+ is bonded to seven O2- atoms to form distorted YO7 pentagonal bipyramids that share corners with four equivalent YO7 pentagonal bipyramids, edges with three YO7 pentagonal bipyramids, edges with two equivalent CuO5 square pyramids, a faceface with one YO7 pentagonal bipyramid, and a faceface with one CuO5 square pyramid. There are a spread of Y–O bond distances ranging from 2.30–2.38 Å. In the eighth Y3+ site, Y3+ is bonded to seven O2- atoms to form distorted YO7 pentagonal bipyramids that share corners with four equivalent YO7 pentagonal bipyramids, edges with three YO7 pentagonal bipyramids, edges with two equivalent CuO5 square pyramids, a faceface with one YO7 pentagonal bipyramid, and a faceface with one CuO5 square pyramid. There are a spread of Y–O bond distances ranging from 2.30–2.38 Å. There are four inequivalent Cu2+ sites. In the first Cu2+ site, Cu2+ is bonded to five O2- atoms to form CuO5 square pyramids that share corners with five YO7 pentagonal bipyramids, edges with three YO7 pentagonal bipyramids, and a faceface with one YO7 pentagonal bipyramid. There are a spread of Cu–O bond distances ranging from 2.00–2.33 Å. In the second Cu2+ site, Cu2+ is bonded to five O2- atoms to form CuO5 square pyramids that share corners with five YO7 pentagonal bipyramids, edges with three YO7 pentagonal bipyramids, and a faceface with one YO7 pentagonal bipyramid. There are a spread of Cu–O bond distances ranging from 1.98–2.30 Å. In the third Cu2+ site, Cu2+ is bonded to five O2- atoms to form CuO5 square pyramids that share corners with five YO7 pentagonal bipyramids, edges with three YO7 pentagonal bipyramids, and a faceface with one YO7 pentagonal bipyramid. There are a spread of Cu–O bond distances ranging from 1.99–2.31 Å. In the fourth Cu2+ site, Cu2+ is bonded to five O2- atoms to form CuO5 square pyramids that share corners with five YO7 pentagonal bipyramids, edges with three YO7 pentagonal bipyramids, and a faceface with one YO7 pentagonal bipyramid. There are a spread of Cu–O bond distances ranging from 1.98–2.30 Å. There are twelve inequivalent O2- sites. In the first O2- site, O2- is bonded to two equivalent Ba2+, one Sr2+, two Y3+, and one Cu2+ atom to form distorted OBa2SrY2Cu octahedra that share corners with two equivalent OBa2SrY2Cu octahedra and edges with two equivalent OBaSr2Y2Cu octahedra. The corner-sharing octahedral tilt angles are 3°. In the second O2- site, O2- is bonded to three Ba2+, two Y3+, and one Cu2+ atom to form a mixture of distorted corner and edge-sharing OBa3Y2Cu octahedra. The corner-sharing octahedral tilt angles are 5°. In the third O2- site, O2- is bonded to one Ba2+, two equivalent Sr2+, two Y3+, and one Cu2+ atom to form distorted OBaSr2Y2Cu octahedra that share corners with two equivalent OBaSr2Y2Cu octahedra and edges with two equivalent OBa2SrY2Cu octahedra. The corner-sharing octahedral tilt angles are 4°. In the fourth O2- site, O2- is bonded to three Ba2+, two Y3+, and one Cu2+ atom to form a mixture of distorted corner and edge-sharing OBa3Y2Cu octahedra. The corner-sharing octahedral tilt angles are 5°. In the fifth O2- site, O2- is bonded in a 4-coordinate geometry to two Ba2+, three Y3+, and one Cu2+ atom. In the sixth O2- site, O2- is bonded in a 4-coordinate geometry to one Ba2+, one Sr2+, three Y3+, and one Cu2+ atom. In the seventh O2- site, O2- is bonded in a 4-coordinate geometry to one Ba2+, one Sr2+, three Y3+, and one Cu2+ atom. In the eighth O2- site, O2- is bonded in a 4-coordinate geometry to two Ba2+, three Y3+, and one Cu2+ atom. In the ninth O2- site, O2- is bonded in a 4-coordinate geometry to two Ba2+, three Y3+, and one Cu2+ atom. In the tenth O2- site, O2- is bonded in a 4-coordinate geometry to one Ba2+, three Y3+, and one Cu2+ atom. In the eleventh O2- site, O2- is bonded in a 4-coordinate geometry to two Ba2+, three Y3+, and one Cu2+ atom. In the twelfth O2- site, O2- is bonded in a 4-coordinate geometry to one Ba2+, one Sr2+, three Y3+, and one Cu2+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Y2AlFe3 by Materials Project

Y2Fe3Al is Cubic Laves-derived structured and crystallizes in the trigonal R-3m space group. The structure is three-dimensional. Y is bonded in a 12-coordinate geometry to four equivalent Y, nine equivalent Fe, and three equivalent Al atoms. There are one shorter (3.13 Å) and three longer (3.23 Å) Y–Y bond lengths. There are six shorter (3.05 Å) and three longer (3.10 Å) Y–Fe bond lengths. All Y–Al bond lengths are 3.07 Å. Fe is bonded to six equivalent Y, four equivalent Fe, and two equivalent Al atoms to form FeY6Al2Fe4 cuboctahedra that share corners with four equivalent AlY6Fe6 cuboctahedra, corners with fourteen equivalent FeY6Al2Fe4 cuboctahedra, edges with six equivalent FeY6Al2Fe4 cuboctahedra, faces with six equivalent AlY6Fe6 cuboctahedra, and faces with twelve equivalent FeY6Al2Fe4 cuboctahedra. All Fe–Fe bond lengths are 2.61 Å. Both Fe–Al bond lengths are 2.61 Å. Al is bonded to six equivalent Y and six equivalent Fe atoms to form AlY6Fe6 cuboctahedra that share corners with six equivalent AlY6Fe6 cuboctahedra, corners with twelve equivalent FeY6Al2Fe4 cuboctahedra, edges with six equivalent AlY6Fe6 cuboctahedra, and faces with eighteen equivalent FeY6Al2Fe4 cuboctahedra.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Y3Pd by Materials Project

Y3Pd is Cementite structured and crystallizes in the orthorhombic Pnma space group. The structure is two-dimensional and consists of two Y3Pd sheets oriented in the (0, 0, 1) direction. there are two inequivalent Y sites. In the first Y site, Y is bonded in a distorted bent 150 degrees geometry to two equivalent Pd atoms. There are one shorter (2.89 Å) and one longer (2.95 Å) Y–Pd bond lengths. In the second Y site, Y is bonded in a 2-coordinate geometry to two equivalent Pd atoms. There are one shorter (2.87 Å) and one longer (2.93 Å) Y–Pd bond lengths. Pd is bonded in a 6-coordinate geometry to six Y atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Y5Pt3 by Materials Project

Y5Pt3 crystallizes in the hexagonal P6_3/mcm space group. The structure is three-dimensional. there are two inequivalent Y sites. In the first Y site, Y is bonded in a 6-coordinate geometry to six equivalent Pt atoms. All Y–Pt bond lengths are 3.06 Å. In the second Y site, Y is bonded in a 5-coordinate geometry to five equivalent Pt atoms. There are a spread of Y–Pt bond distances ranging from 2.91–3.32 Å. Pt is bonded in a 9-coordinate geometry to nine Y atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on YTm3(SnPd2)4 by Materials Project

Tm3Y(Pd2Sn)4 is Tungsten-derived structured and crystallizes in the trigonal R-3m space group. The structure is three-dimensional. there are two inequivalent Tm sites. In the first Tm site, Tm is bonded in a body-centered cubic geometry to eight Pd and six Sn atoms. There are a spread of Tm–Pd bond distances ranging from 2.89–2.94 Å. All Tm–Sn bond lengths are 3.38 Å. In the second Tm site, Tm is bonded in a body-centered cubic geometry to eight Pd and six equivalent Sn atoms. There are two shorter (2.91 Å) and six longer (2.94 Å) Tm–Pd bond lengths. All Tm–Sn bond lengths are 3.38 Å. Y is bonded in a body-centered cubic geometry to eight Pd and six equivalent Sn atoms. All Y–Pd bond lengths are 2.94 Å. All Y–Sn bond lengths are 3.39 Å. There are eight inequivalent Pd sites. In the first Pd site, Pd is bonded in a body-centered cubic geometry to four Tm and four equivalent Sn atoms. There are one shorter (2.92 Å) and three longer (2.94 Å) Pd–Tm bond lengths. There are one shorter (2.91 Å) and three longer (2.94 Å) Pd–Sn bond lengths. In the second Pd site, Pd is bonded in a body-centered cubic geometry to one Tm, three equivalent Y, and four equivalent Sn atoms. The Pd–Tm bond length is 2.89 Å. All Pd–Y bond lengths are 2.94 Å. There are three shorter (2.93 Å) and one longer (2.94 Å) Pd–Sn bond lengths. In the third Pd site, Pd is bonded in a body-centered cubic geometry to four Tm and four equivalent Sn atoms. There are one shorter (2.92 Å) and three longer (2.94 Å) Pd–Tm bond lengths. There are one shorter (2.91 Å) and three longer (2.94 Å) Pd–Sn bond lengths. In the fourth Pd site, Pd is bonded in a body-centered cubic geometry to four Tm and four Sn atoms. All Pd–Tm bond lengths are 2.94 Å. There are one shorter (2.91 Å) and three longer (2.94 Å) Pd–Sn bond lengths. In the fifth Pd site, Pd is bonded in a body-centered cubic geometry to four Tm and four equivalent Sn atoms. There are one shorter (2.91 Å) and three longer (2.94 Å) Pd–Sn bond lengths. In the sixth Pd site, Pd is bonded in a body-centered cubic geometry to one Tm, three equivalent Y, and four equivalent Sn atoms. There are three shorter (2.93 Å) and one longer (2.94 Å) Pd–Sn bond lengths. In the seventh Pd site, Pd is bonded in a body-centered cubic geometry to three equivalent Tm, one Y, and four Sn atoms. There are one shorter (2.89 Å) and three longer (2.94 Å) Pd–Sn bond lengths. In the eighth Pd site, Pd is bonded in a body-centered cubic geometry to four Tm and four Sn atoms. There are one shorter (2.91 Å) and three longer (2.94 Å) Pd–Sn bond lengths. There are two inequivalent Sn sites. In the first Sn site, Sn is bonded in a distorted body-centered cubic geometry to six Tm and eight Pd atoms. In the second Sn site, Sn is bonded in a distorted body-centered cubic geometry to three equivalent Tm, three equivalent Y, and eight Pd atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Y3Mn3Ga2Ge by Materials Project

Y3Mn3GeGa2 crystallizes in the hexagonal P-6 space group. The structure is three-dimensional. Y is bonded in a 5-coordinate geometry to six equivalent Mn, three Ga, and two equivalent Ge atoms. There are a spread of Y–Mn bond distances ranging from 3.21–3.31 Å. There are one shorter (2.95 Å) and two longer (2.96 Å) Y–Ga bond lengths. Both Y–Ge bond lengths are 2.95 Å. Mn is bonded in a 12-coordinate geometry to six equivalent Y, two equivalent Mn, three Ga, and one Ge atom. Both Mn–Mn bond lengths are 2.81 Å. There are two shorter (2.63 Å) and one longer (2.79 Å) Mn–Ga bond lengths. The Mn–Ge bond length is 2.76 Å. There are two inequivalent Ga sites. In the first Ga site, Ga is bonded in a 9-coordinate geometry to six equivalent Y and three equivalent Mn atoms. In the second Ga site, Ga is bonded in a distorted q6 geometry to three equivalent Y and six equivalent Mn atoms. Ge is bonded in a 9-coordinate geometry to six equivalent Y and three equivalent Mn atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2021

Comparative study of three yttrium organometallic compounds for the stabilization of the cubic phase in YSZ deposited by PE-CVD

In this work, the efficiencies of three organometallic yttrium precursors used to produce YSZ coatings by plasma-enhanced chemical vapor deposition were studied. Yttrium (III) acetylacetonate, Y (acac) 3 , yttrium (III) hexafluoroacetylacetonate, Y (acacF 6 ) 3 , and yttrium (III) tris(2,2,6,6-tetramethyl-3,5-heptanedionate), Y (tmhd) 3 , were used to stabilize the cubic phase in zirconia deposited at temperatures from 500 to 800 °C. Our results showed that at temperatures between 500 and 600 °C, Y (tmhd) 3 appeared to be the most efficient dopant as it introduced the highest concentration of yttria (1–2.7 mol%) with only 6.4–5.6 at.% carbon. However, at 700 and 800 °C, Y (acac) 3 introduced twice as much yttria (8–15 mol%) as Y (tmhd) 3 with almost the same amount of carbon (5.4–3 at.%). Conversely, Y (acacF6)3 was the least efficient as it maintained a low concentration of yttria of around 0.7–1.8 mol% with 3.6–8.2 at.% carbon for all the deposition temperatures. Among these precursors, only Y (acac) 3 surpassed 8 mol% yttria and achieved a fully stabilized cubic phase at 800 °C, with the remaining samples stabilizing only the tetragonal phase. The tetragonal phase was stabilized due to the formation of crystallites of around 10 nm. The observed difference in the efficiency of the three precursors was correlated to important differences in their decomposition behavior as observed by mass spectrometry and thermogravimetry/differential scanning calorimetry.

36 MATERIALS SCIENCE↗
DOE OSTI2021

A density functional theory and neutron diffraction study of the ambient condition properties of sub-stoichiometric yttrium hydride

Several mechanical and thermophysical properties are required as a function of non-stoichiometry for the successful implementation of YH 2-x for nuclear reactor moderator applications. Density functional theory calculations, in combination with neutron diffraction experiments, were used to study the structural and mechanical properties of YH 2-x . Point defect analysis indicated H occupation primarily at the tetrahedral site within an fcc Y sub-lattice, confirming a fluorite YH 2 structure. The small positive formation energy for H vacancies under Y-rich conditions predicted that hypo-stoichiometry is accommodated by Y+YH 2 at ambient conditions and by H vacancies in the YH 2-x single phase that is relevant to high temperatures. Neutron diffraction studies were used to confirm both the occupation of H on tetrahedral sites and the near-stoichiometric composition of the hydride phase in the two-phase Y+YH 2 region of the phase diagram that dominates at room temperature. Energy minimized special-quasirandom-structures of H vacancies were used to calculate lattice parameters, elastic constants, and several other properties as a function of composition for the single phase YH 2-x . The lattice parameter of YH 2-x decreased by only 0.004 Å with increasing H/Y for the range 1.31 ≤ H / Y ≤ 2.0 indicating a negligible effect on lattice parameters due to vacancy formation. In the two-phase region, however, calculations predicted the density of z Y + ( 1 - z ) Y H 2 - x to increase with decreasing H/Y at lower temperatures due to the increased fraction of high-density Y metal. Additionally, for the high temperature single phase, decreasing H/Y reduced the density as a consequence of the lattice expansion associated with vacancy formation. All elastic constants and moduli increased with increasing hydrogen content in single-phase YH 2-x .

36 MATERIALS SCIENCE↗
DOE OSTI2026

Mechanism of Tyrosine-Driven Deprotonation in Photosystem II Revealed by Multiscale Simulations

Photosystem II (PSII) drives light-induced water oxidation via stepwise redox transitions of its oxygen-evolving complex (OEC), a Mn 4 Ca cluster advancing through five intermediate S-states (S 0 –S 4 ). The S 2 → S 3 transition involves a redox event in which a Mn ion donates an electron to the redox-active tyrosine YZ, coupled to deprotonation of an OEC-bound water ligand─yet the underlying coupling mechanism remains unresolved. Time-resolved serial femtosecond crystallography (TR-SFX) has revealed transient electron density shifts near the redox-active tyrosine Y Z , interpreted as sequential oxidation and reduction, with reduction initiating ∼1 μs after excitation and substantially progressed by 30 μs. However, this interpretation conflicts with kinetics from photothermal beam deflection (PBD), time-resolved X-ray absorption spectroscopy (TR-XAS), and electron paramagnetic resonance (EPR), which place electron transfer at 190–400 μs and proton transfer around 30 μs. Here, we reconcile these discrepancies using quantum mechanics/molecular mechanics (QM/MM) and molecular dynamics (MD) simulations. We show that oxidation of P680 and Y Z breaks the symmetry of the nearby hydrogen bonds involving water molecule W4, displacing Y Z and replicating the TR-SFX features of Y Z and Q165 observed at 1 μs. This local perturbation propagates through a hydrogen-bond network, transmitting the electrostatic signal from Y Z to the E65-E312 dyad and triggering redox-coupled deprotonation via the Cl1 channel. By 30 μs, the hydrogen-bond symmetry is restored through deprotonation of W2 (or alternatively W1), reproducing the disappearance of TR-SFX density differences around Y Z and Q165 without requiring Y Z reduction. Our proposed mechanism also gives molecular insights into the O6* density, assigning it to water reorganization rather than a discrete Ca-bound hydroxide species. Here, our results reveal a detailed atomistic mechanism linking Y Z oxidation to long-range proton release and suggest a functional role for the nearby Cl – ion in proton transfer. More broadly, this study underscores the importance of hydrogen-bond dynamics in mediating redox-driven proton transport and demonstrates how integrative simulations can resolve mechanistic ambiguities.

Deprotonation↗
DOE OSTI2020

Re-evaluation of the TSL for Yttrium Hydride

Yttrium hydride (YH x ) is of interest as a high-temperature moderator material in advanced nuclear reactor systems because of its superior ability to retain hydrogen at elevated temperatures. Thermal neutron scattering laws (TSL) for hydrogen bound in yttrium hydride (H-YH 2 ) and yttrium bound in yttrium hydride (Y-YH 2 ) were previously evaluated by Naval Nuclear Laboratory using the ab initio approach and released in ENDF/B-VIII.0. In that work, density functional theory, incorporating the generalized gradient approximation (GGA) for the exchange-correlation energy, was used to simulate the face-centered cubic structure of YH 2 and calculate the interatomic Hellmann-Feynman forces for a 2×2×2 supercell containing 96 atoms. Lattice dynamics calculations using PHONON were used to determine the phonon density of states. The calculated phonon density of states for H and Y in YH 2 were then used to prepare H-YH 2 and Y-YH 2 TSL evaluations, in the incoherent approximation, using the LEAPR module of NJOY. In addition, elastic scattering was assumed to be incoherent for both H and Y. While the incoherent elastic scattering approximation is appropriate for H-YH 2 , it introduces an undesirable approximation for Y-YH 2 . In this work, we re-evaluate the TSL for Y-YH 2 using FLASSH (Full Law Analysis Scattering System Hub). Y-YH 2 is evaluated using the FLASSH generalized coherent elastic scattering capability in order to capture the Bragg peaks associated with the YH 2 crystal structure which were neglected in the prior NJOY-based evaluation due to limitations in LEAPR. An experimental approach to validate the Y-YH 2 TSL using neutron transmission measurements is discussed.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2026

Data for Protoplast Fusion as a Strategy to Increase Ploidy in Rhodotorula toruloides for Strain Development

Rhodotorula toruloides is a red oleaginous yeast with growing commercial interest because of its hardiness and exceptional lipid production capacity. Because it is a basidiomycete yeast with a complex life cycle, many of the classical breeding methods used with ascomycetes are unavailable for strain improvement. However, we have been able to construct polyploid yeast by fusing protoplasts of parents with the same mating type. Fusing of Y-6985 (A2) and Y-48190 (A2), which had been transformed with complementary antibiotic markers, led to the recovery of two diploids and one triploid. The stability of the fusion yeasts was tested by plating them on non-selective medium after several growth cycles under antibiotics and then testing five colonies per strain for nuclear DNA contents using flow cytometry and standard cell cycle analysis: the triploid and one diploid were stable. Fusants inherited their mitochondria from a single parent, which was demonstrated using restriction fragment length polymorphism (RFLP) of mitochondrial DNA. The phenotypic properties of the parents and fusants were compared in glucose fed-batch bioreactor studies and cellulosic sugar batch cultures. The final lipid titers for the fed-batch cultures were 24.9–39.7 g/L with Y-6985 and the diploid and triploid performing the best and worst, respectively. The fusants demonstrated intermediate hardiness for growth on hydrolysate prepared with dilute-acid pretreated switchgrass and were outperformed by Y-48190. Unlike one of the haploid parents, the fusants grew in 70% v/v concentrated hydrolysate. However, they did not grow as fast as the other haploid. In this study, a modernized protoplast fusion method is resurrected a useful tool for strain development in this yeast, which is complementary with other available methods.

FOS: Biological sciences↗
DOE OSTI2021

Winning Asset Management Improvement Team: Maintenance Planning and Scheduling in a Highly Regulated Environment

The Y-12 National Complex (Y-12) site has numerous aging facilities that are crucial to the Department of Energy and the national security strategy for the nation. Y-12’s commitment to safety and regulatory compliance is of the highest importance. The commitment to meet the national security mission also creates additional rigor and complexity to the everyday maintenance and planning process. Y-12 is a collection of many facilities, both old and new, nestled between two ridges in Oak Ridge, TN. Y-12 was made with the short-term focus of ending “The Great War” through the creation of the worlds’ first atomic bomb. Almost eighty (80) years have passed since the groundbreaking, with the mission of the site changing from decade to decade. While the mission has changed, the way Y-12 employees continuously meet the challenge has not. The site was created to react and overcome; Y-12 still takes pride in the ability to react and overcome. The difference is the site is no longer ignorant to the need for a better way to manage the aging facilities and infrastructure. Shear willpower and determination was once the way to reach the objectives, but as a wise man once said, “Work smarter, not harder.” The business case for change started within the senior leadership at Y-12. A team of managers sat down and dictated objectives to provide a clear scope for the maintenance planning and scheduling optimization team, to include our Eruditio integrated blended learning coaches. In addition to providing the direction, they also made themselves available for escalation of issues in the event the team ran in to road blocks.

99 GENERAL AND MISCELLANEOUS↗