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At least 559 records · Page 31

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NASA NTRS2011

Rb-Sr and Sm-Nd Study of Asuka 881394: Evidence of "Late" Metamorphism

The Asuka 881394 achondrite contains fossil Al-26 and Mn-53 [1,2,3] and has a Pb-207/Pb-206 age of 4566.5 plus or minus 0.2 Ma [3], the oldest for an achondrite. Preliminary results showed initial Sm-146/Sm-144 = (7.4 plus or minus 1.2) x 10(exp -3), indicative of an ancient age, but Rb-87 - Sr-87 and Sm-147 - Nd-143 ages of 4370 plus or minus 60 and 4490 plus or minus 20 Ma, resp. [1], were younger than expected from the presence of short-lived nuclides. We revisit the Rb-Sr and Sm-Nd chronology of A881394 in an attempt to establish whether late metamorphism led to inconsistency in its apparent ages.

Nyquist, L. E.↗

NASA NTRS2012

Rb-Sr and Sm-Nd Isotopic Studies of Lunar Green and Orange Glasses

Lunar volcanic glassy beads have been considered as quenched basaltic magmas derived directly from deep lunar mantle during fire-fountaining eruptions [1]. Since these sub-mm size glassy melt droplets were cooled in a hot gaseous medium during free flight [2], they have not been subject to mineral fractionations. Thus, they represent primary magmas and are the best samples for the investigation of the lunar mantle. Previously, we presented preliminary Rb- Sr and Sm-Nd isotopic results for green and orange glassy samples from green glass clod 15426,63 and orange soil 74220,44, respectively [3]. Using these isotopic data, initial Sr-87/Sr-86 and Nd ratios for these pristine mare glass sources can be calculated from their respective crystallization ages previously determined by other age-dating techniques. These isotopic data were used to evaluate the mineralogy of the mantle sources. In this report, we analyzed additional glassy samples in order to further characterize isotopic signatures of their source regions. Also, we'll postulate a relationship between these two major mare basalt source mineralogies in the context of lunar magma ocean dynamics.

Shih, C.-Y.↗

NASA NTRS2012

Additional Sr Isotopic Heterogeneity in Zagami Olivine-Rich Lithology

Prior isotopic analyses of Zagami have established differing initial Sr-87/Sr-86 (ISr) ratios of among Zagami lithologies, fine-grained (FG), coarse-grained (CG), and dark mottled lithologies (DML)]. The Zagami sample (KPM-NLH000057) newly allocated from the Kanagawa Prefectural Museum of Natural History contained DML and the Ol-rich lithology which included more ferroan olivines (Ol-rich: Fa(sub 97- 99) vs late-stage melt pockets: Fa(sub 90-97)]). We have combined mineralogy-petrology and Rb-Sr isotopic studies on the Kanagawa Zagami sample, which will provide additional clues to the genesis of enriched shergottites and to the evolution of Martian crust and mantle

Misawa, K.↗

NASA NTRS2013

Ar-Ar and Rb-Sr Ages of the Tissint Olivine-phyric Martian Shergottite

The fifth martian meteorite fall, Tissint, is an olivine-phyric shergottite that contains olivine macrocrysts (approximately 1.5 mm) [1]. [2] reported the Sm-Nd age of Tissint as 596 plus or minus 23 Ma along with Rb-Sr data that defined no isochron. [3] reported Lu-Hf and Sm-Nd ages of 583 plus or minus 86 Ma and 616 plus or minus 67 Ma, respectively. The cosmic-ray exposure ages of Tissint are 1.10 plus or minus 0.15 Ma based on 10Be [4], and 1.0-1.1 Ma, based on 3He, 21Ne, and 38Ar [5,6].We report Ar-Ar ages and Rb-Sr data.

Park, J.↗

NASA NTRS2019

Aerodynamics for the ADEPT SR-1 Flight Experiment

Adaptable, Deployable, Entry, and Placement Technology (ADEPT) is a combination of a heatshield and an aerodynamic decelerator for atmospheric entry applications. The ADEPT Sounding Rocket (SR)-1 mission was a suborbital flight experiment of an 0.7 m-diameter ADEPT to verify system-level performance and to characterize dynamic stability behavior. The aerodynamic database for ADEPT SR-1 was constructed from non-continuum and continuum flowfield computations, along with data from recent ADEPT ground testing and the IRVE-3 flight test vehicle. High-altitude (free-molecular and transitional regimes) data were generated using DSMC methods. Pre-flight predictions of continuum static aerodynamics coefficients were derived from Reynolds-Averaged Navier-Stokes solutions at conditions along a design trajectory, with comparisons to available ground test data of the nano-ADEPT geometry. Dynamic pitch damping characteristics were taken from functional forms developed for the IRVE-3 flight test vehicle through ballistic range testing. Comparison of pre-flight predictions to post-flight reconstruction of aerodynamic force and moment coefficients is presented.

Korzun, Ashley M.↗

NASA NTRSDate not supplied

The Venus Atmospheric Sample Return (VATMOS-SR) Mission Concept

VATMOS-SR (Venus ATMOSpheric - Sample Return) is a small space- craft mission concept that would return several gas samples from the upper atmosphere of Venus (< 110 km) to Earth for scientific analysis. This could be the first sample return mission for an extraterrestrial atmosphere and potentially the first sample return from an Earth-sized planet. The VATMOS-SR mission concept consists of a SmallSat atmospheric sampling probe (45 deg. sphere/cone geometry, <1 m diameter) that is designed to skim through the Venus upper atmosphere and ac- quire gas samples below the homopause altitude (around ~110 km altitude), where the different atmospheric gases are mixed. The velocity of the spacecraft where sampling would occur is expected to be between ~10.5 km/s and ~13.1 km/s, depending on the trajectory chosen (e.g. trajectory shown in Fig. 1).

direct simulation Monte Carlo↗

NASA NTRSDate not supplied

The Venus Atmospheric Sample Return (VATMOS-SR) Mission Concept

direct simulation Monte Carlo↗

DOE OSTI2020

Materials Data on Sr(Ni2B)6 by Materials Project

SrNi12B6 crystallizes in the trigonal R-3m space group. The structure is three-dimensional. Sr2+ is bonded in a hexagonal planar geometry to six equivalent B3- atoms. All Sr–B bond lengths are 3.19 Å. There are two inequivalent Ni+1.33+ sites. In the first Ni+1.33+ site, Ni+1.33+ is bonded to four equivalent B3- atoms to form a mixture of distorted corner and edge-sharing NiB4 tetrahedra. There are two shorter (2.04 Å) and two longer (2.11 Å) Ni–B bond lengths. In the second Ni+1.33+ site, Ni+1.33+ is bonded in a T-shaped geometry to three equivalent B3- atoms. There are two shorter (2.06 Å) and one longer (2.08 Å) Ni–B bond lengths. B3- is bonded in a 7-coordinate geometry to one Sr2+ and seven Ni+1.33+ atoms.

36 MATERIALS SCIENCE↗

DOE OSTI2020

Materials Data on Sr(ScS2)2 by Materials Project

SrSc2S4 crystallizes in the orthorhombic Pnma space group. The structure is three-dimensional. Sr2+ is bonded in a 8-coordinate geometry to eight S2- atoms. There are a spread of Sr–S bond distances ranging from 3.03–3.20 Å. There are two inequivalent Sc3+ sites. In the first Sc3+ site, Sc3+ is bonded to six S2- atoms to form a mixture of edge and corner-sharing ScS6 octahedra. The corner-sharing octahedra tilt angles range from 48–59°. There are a spread of Sc–S bond distances ranging from 2.55–2.63 Å. In the second Sc3+ site, Sc3+ is bonded to six S2- atoms to form a mixture of edge and corner-sharing ScS6 octahedra. The corner-sharing octahedra tilt angles range from 48–59°. There are a spread of Sc–S bond distances ranging from 2.57–2.67 Å. There are four inequivalent S2- sites. In the first S2- site, S2- is bonded in a 5-coordinate geometry to two equivalent Sr2+ and three equivalent Sc3+ atoms. In the second S2- site, S2- is bonded to two equivalent Sr2+ and three Sc3+ atoms to form a mixture of distorted edge and corner-sharing SSr2Sc3 trigonal bipyramids. In the third S2- site, S2- is bonded to two equivalent Sr2+ and three equivalent Sc3+ atoms to form a mixture of distorted edge and corner-sharing SSr2Sc3 square pyramids. In the fourth S2- site, S2- is bonded in a 5-coordinate geometry to two equivalent Sr2+ and three Sc3+ atoms.

36 MATERIALS SCIENCE↗

DOE OSTI2020

Materials Data on Sr(ScTe2)2 by Materials Project

SrSc2Te4 crystallizes in the orthorhombic Pnma space group. The structure is three-dimensional. Sr2+ is bonded in a 8-coordinate geometry to eight Te2- atoms. There are a spread of Sr–Te bond distances ranging from 3.41–3.65 Å. There are two inequivalent Sc3+ sites. In the first Sc3+ site, Sc3+ is bonded to six Te2- atoms to form a mixture of corner and edge-sharing ScTe6 octahedra. The corner-sharing octahedra tilt angles range from 47–57°. There are a spread of Sc–Te bond distances ranging from 2.92–2.99 Å. In the second Sc3+ site, Sc3+ is bonded to six Te2- atoms to form a mixture of corner and edge-sharing ScTe6 octahedra. The corner-sharing octahedra tilt angles range from 47–57°. There are a spread of Sc–Te bond distances ranging from 2.91–3.01 Å. There are four inequivalent Te2- sites. In the first Te2- site, Te2- is bonded in a 5-coordinate geometry to two equivalent Sr2+ and three equivalent Sc3+ atoms. In the second Te2- site, Te2- is bonded in a 5-coordinate geometry to two equivalent Sr2+ and three Sc3+ atoms. In the third Te2- site, Te2- is bonded to two equivalent Sr2+ and three equivalent Sc3+ atoms to form a mixture of distorted corner and edge-sharing TeSr2Sc3 square pyramids. In the fourth Te2- site, Te2- is bonded to two equivalent Sr2+ and three Sc3+ atoms to form a mixture of distorted corner and edge-sharing TeSr2Sc3 trigonal bipyramids.

36 MATERIALS SCIENCE↗

DOE OSTI2020

Materials Data on Sr(H9O5)2 by Materials Project

(SrH17O9)2H2O2 crystallizes in the tetragonal P4/ncc space group. The structure is two-dimensional and consists of four water molecules and two SrH17O9 sheets oriented in the (0, 0, 1) direction. In each SrH17O9 sheet, Sr2+ is bonded in a 8-coordinate geometry to eight O2- atoms. There are four shorter (2.66 Å) and four longer (2.68 Å) Sr–O bond lengths. There are five inequivalent H1+ sites. In the first H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 1.00 Å. In the second H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 1.00 Å. In the third H1+ site, H1+ is bonded in a distorted linear geometry to two O2- atoms. There is one shorter (1.02 Å) and one longer (1.65 Å) H–O bond length. In the fourth H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.98 Å. In the fifth H1+ site, H1+ is bonded in a distorted single-bond geometry to one O2- atom. The H–O bond length is 1.01 Å. There are three inequivalent O2- sites. In the first O2- site, O2- is bonded in a water-like geometry to one Sr2+ and two H1+ atoms. In the second O2- site, O2- is bonded in a single-bond geometry to five H1+ atoms. In the third O2- site, O2- is bonded in a water-like geometry to one Sr2+ and two H1+ atoms.

36 MATERIALS SCIENCE↗

DOE OSTI2020

Materials Data on Sr(YS2)2 by Materials Project

SrY2S4 crystallizes in the orthorhombic Pnma space group. The structure is three-dimensional. Sr2+ is bonded in a 8-coordinate geometry to eight S2- atoms. There are a spread of Sr–S bond distances ranging from 3.10–3.34 Å. There are two inequivalent Y3+ sites. In the first Y3+ site, Y3+ is bonded to six S2- atoms to form a mixture of edge and corner-sharing YS6 octahedra. The corner-sharing octahedra tilt angles range from 48–64°. There are a spread of Y–S bond distances ranging from 2.73–2.78 Å. In the second Y3+ site, Y3+ is bonded to six S2- atoms to form a mixture of edge and corner-sharing YS6 octahedra. The corner-sharing octahedra tilt angles range from 48–64°. There are a spread of Y–S bond distances ranging from 2.69–2.78 Å. There are four inequivalent S2- sites. In the first S2- site, S2- is bonded to two equivalent Sr2+ and three equivalent Y3+ atoms to form a mixture of edge and corner-sharing SSr2Y3 square pyramids. In the second S2- site, S2- is bonded in a 5-coordinate geometry to two equivalent Sr2+ and three Y3+ atoms. In the third S2- site, S2- is bonded to two equivalent Sr2+ and three equivalent Y3+ atoms to form a mixture of distorted edge and corner-sharing SSr2Y3 trigonal bipyramids. In the fourth S2- site, S2- is bonded in a 5-coordinate geometry to two equivalent Sr2+ and three Y3+ atoms.

36 MATERIALS SCIENCE↗

DOE OSTI2020

Materials Data on Sr(BiO2)2 by Materials Project

SrBi2O4 crystallizes in the monoclinic C2/m space group. The structure is two-dimensional and consists of two SrBi2O4 sheets oriented in the (1, 0, 0) direction. Sr2+ is bonded to seven O2- atoms to form distorted edge-sharing SrO7 hexagonal pyramids. There are a spread of Sr–O bond distances ranging from 2.52–2.87 Å. There are two inequivalent Bi3+ sites. In the first Bi3+ site, Bi3+ is bonded in a distorted square co-planar geometry to four O2- atoms. There are a spread of Bi–O bond distances ranging from 2.06–2.30 Å. In the second Bi3+ site, Bi3+ is bonded in a distorted rectangular see-saw-like geometry to four O2- atoms. There are a spread of Bi–O bond distances ranging from 2.05–2.30 Å. There are four inequivalent O2- sites. In the first O2- site, O2- is bonded to one Sr2+ and three Bi3+ atoms to form distorted OSrBi3 trigonal pyramids that share corners with three OSr3Bi tetrahedra, corners with two equivalent OSrBi3 trigonal pyramids, and edges with three OSr3Bi tetrahedra. In the second O2- site, O2- is bonded to three equivalent Sr2+ and one Bi3+ atom to form distorted OSr3Bi tetrahedra that share corners with nine OSr3Bi tetrahedra, corners with two equivalent OSrBi3 trigonal pyramids, edges with three OSr3Bi tetrahedra, and an edgeedge with one OSrBi3 trigonal pyramid. In the third O2- site, O2- is bonded to three equivalent Sr2+ and one Bi3+ atom to form distorted OSr3Bi tetrahedra that share corners with nine OSr3Bi tetrahedra, a cornercorner with one OSrBi3 trigonal pyramid, edges with three OSr3Bi tetrahedra, and edges with two equivalent OSrBi3 trigonal pyramids. In the fourth O2- site, O2- is bonded in a 3-coordinate geometry to three Bi3+ atoms.

36 MATERIALS SCIENCE↗

DOE OSTI2020

Materials Data on Sr(YS2)2 by Materials Project

SrY2S4 crystallizes in the tetragonal I-42d space group. The structure is three-dimensional. Sr2+ is bonded in a 8-coordinate geometry to eight equivalent S2- atoms. There are four shorter (2.91 Å) and four longer (3.13 Å) Sr–S bond lengths. Y3+ is bonded in a 8-coordinate geometry to eight equivalent S2- atoms. There are a spread of Y–S bond distances ranging from 2.75–3.16 Å. S2- is bonded in a 6-coordinate geometry to two equivalent Sr2+ and four equivalent Y3+ atoms.

36 MATERIALS SCIENCE↗

DOE OSTI2020

Materials Data on Sr(NdS2)2 by Materials Project

SrNd2S4 crystallizes in the tetragonal I-42d space group. The structure is three-dimensional. Sr2+ is bonded to eight equivalent S2- atoms to form distorted SrS8 hexagonal bipyramids that share corners with eight equivalent NdS8 hexagonal bipyramids, edges with four equivalent SrS8 hexagonal bipyramids, and faces with eight equivalent NdS8 hexagonal bipyramids. There are four shorter (2.97 Å) and four longer (3.15 Å) Sr–S bond lengths. Nd3+ is bonded to eight equivalent S2- atoms to form distorted NdS8 hexagonal bipyramids that share corners with four equivalent SrS8 hexagonal bipyramids, corners with four equivalent NdS8 hexagonal bipyramids, edges with four equivalent NdS8 hexagonal bipyramids, faces with four equivalent SrS8 hexagonal bipyramids, and faces with four equivalent NdS8 hexagonal bipyramids. There are a spread of Nd–S bond distances ranging from 2.87–3.11 Å. S2- is bonded to two equivalent Sr2+ and four equivalent Nd3+ atoms to form a mixture of distorted edge, corner, and face-sharing SSr2Nd4 octahedra. The corner-sharing octahedra tilt angles range from 16–51°.

36 MATERIALS SCIENCE↗

DOE OSTI2020

Materials Data on Sr(PRu)2 by Materials Project

SrRu2P2 crystallizes in the tetragonal I4/mmm space group. The structure is three-dimensional. Sr2+ is bonded in a body-centered cubic geometry to eight equivalent P3- atoms. All Sr–P bond lengths are 3.33 Å. Ru2+ is bonded to four equivalent P3- atoms to form a mixture of edge and corner-sharing RuP4 tetrahedra. All Ru–P bond lengths are 2.33 Å. P3- is bonded in a 8-coordinate geometry to four equivalent Sr2+ and four equivalent Ru2+ atoms.

36 MATERIALS SCIENCE↗

DOE OSTI2020

Materials Data on Sr(NiAs)2 by Materials Project

SrNi2As2 crystallizes in the tetragonal I4/mmm space group. The structure is three-dimensional. Sr2+ is bonded in a distorted body-centered cubic geometry to eight equivalent As3- atoms. All Sr–As bond lengths are 3.28 Å. Ni2+ is bonded to four equivalent As3- atoms to form a mixture of edge and corner-sharing NiAs4 tetrahedra. All Ni–As bond lengths are 2.38 Å. As3- is bonded in a 9-coordinate geometry to four equivalent Sr2+ and four equivalent Ni2+ atoms.

36 MATERIALS SCIENCE↗

DOE OSTI2020

Materials Data on Sr(MnAs)2 by Materials Project

SrMn2As2 crystallizes in the trigonal P-3m1 space group. The structure is three-dimensional. Sr2+ is bonded to six equivalent As3- atoms to form SrAs6 octahedra that share corners with twelve equivalent MnAs4 tetrahedra, edges with six equivalent SrAs6 octahedra, and edges with six equivalent MnAs4 tetrahedra. All Sr–As bond lengths are 3.14 Å. Mn2+ is bonded to four equivalent As3- atoms to form MnAs4 tetrahedra that share corners with six equivalent SrAs6 octahedra, corners with six equivalent MnAs4 tetrahedra, edges with three equivalent SrAs6 octahedra, and edges with three equivalent MnAs4 tetrahedra. The corner-sharing octahedra tilt angles range from 23–49°. There are one shorter (2.43 Å) and three longer (2.48 Å) Mn–As bond lengths. As3- is bonded in a 7-coordinate geometry to three equivalent Sr2+ and four equivalent Mn2+ atoms.

36 MATERIALS SCIENCE↗