Engineering Papers⌕ Search

SEARCH · Engineering Papers

Results for “Ir”

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

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

At least 1,423 records · Page 79
All sourcesNASA NTRSDOE OSTI
NASA NTRS1993

Geochemical evidences for two chondritic-like cometary or asteroidal impacts before and at the K/T boundary

A number of geological and palaeontological evidences support multiple impacts of cometary showers within a short time (approximately 1-3 Ma) and their connection with mass extinctions. Observations include clustered crater ages, stratigraphic horizons of impact ejecta closely spaced in time, and evidence for stepwise mass extinctions spanning intervals of 1-3 Ma. For the K/T boundary, three candidates, Popigai, Manson, and Yucatan, have been proposed as impact craters. Two distinct strata at the K/T boundary in western North America have been interpreted as evidence for two sequential impacts. If multiple impacts occurred within a time span of about 1 Ma then multiple Ir enrichments should be observed. DSDP Hole 577B on the Shatsky Plateau in the northern Pacific at K/T time is the first site. Samples contain approximately greater than 97 percent CaCO3, which exhibit clear chemical signals associated with asteroidal/cometary impact. Ir, Fe, and Cr data are presented. From the Th-normalized data, two satellite peaks below the major peak at 78 cm and 81 cm of 577B-1-4 are clearly shown. The major Ir peak (K/T boundary) is at 72 cm. Fe and Cr, from C1-like impactor ejecta fallout, also show two peaks at the same positions. For hole 738C on the southern Kerguelen Plateau, Ir values reach a peak concentration of 18 ppb in the clay layer at 96.0-96.2 cm in section 20R-5, and gradually tail off. In the sample 115 cm above the boundary, Ir concentrations have still not reached background levels. From the Ir peak downward to the lowermost sample analyzed at 102 cm, the Ir concentration is still as high as 1.7 ppb. From the Th-normalized data, we observe a small Ir/Th peak at 100-101 cm. Though this peak is within the error margin, the trend is clear. Fe and Cr exhibit the same pattern. The third case is Hole 690C on the Queen Maud Ridge. Again, the Ir/Th plot indicates the strong possibility of satellite peaks at approximately 52 cm. The main peak is at 39-40 cm. For the Stevns Klint K/T boundary layers, the stratification of trace elements appears threefold with peak concentrations in sublayers A1, A3, and B2 for different element groups, including Ir. C1 ratios for many siderophile elements found in combined layers III and IV, corresponding to layers A, B, C, and D, strongly support the impact hypothesis. Also, multiple Ir anomalies in the K/T section at Lattengebirge, Bavarian Alps are reported. Recent works on Ni-rich spinels and Ir at the K/T boundaries clearly establish cometary/asteroidal impacts at the K/T boundary. Lastly, cometary showers can explain the enhanced Ir contents over approximately a 1 Ma interval in Gubbio shales.

Liu, Y.-G.↗
NASA NTRS2011

Infrared and X-Ray Spectroscopy of the Kes 75 Supernova Remnant Shell: Characterizing the Dust and Gas Properties

We present deep Chandra observations and Spitzer Space Telescope infrared (IR) spectroscopy of the shell in the composite supernova remnant (SNR) Kes 75 (G29.7-0.3). The remnant is composed of a central pulsar wind nebula and a bright partial shell in the south that is visible at radio, IR, and X-ray wavelengths. The X-ray emission can be modeled by either a single thermal component with a temperature of approximately 1.5 keY, or with two thermal components with temperatures of 1.5 and 0.2 keY. Previous studies suggest that the hot component may originate from reverse-shocked supernova (SN) ejecta. However, our new analysis shows no definitive evidence for enhanced abundances of Si, S, Ar, Mg, and Fe, as expected from SN ejecta, or for the IR spectral signatures characteristic of confirmed SN condensed dust, thus favoring a circumstellar or interstellar origin for the X-ray and IR emission. The X-ray and IR emission in the shell are spatially correlated, suggesting that the dust particles are collisionally heated by the X-ray emitting gas. The IR spectrum of the shell is dominated by continuum emission from dust with little, or no line emission. Modeling the IR spectrum shows that the dust is heated to a temperature of approximately 140 K by a relatively dense, hot plasma that also gives rise to the hot X-my emission component. The density inferred from the IR emission is significantly higher than the density inferred from the X-ray models, suggesting a low filling factor for this X-my emitting gas. The total mass of the warm dust component is at least 1.3 x 10(exp -2) x solar mass, assuming no significant dust destruction has occurred in the shell. The IR data also reveal the presence of an additional plasma component with a cooler temperature, consistent with the 0.2 keV gas component. Our IR analysis therefore provides an independent verification of the cooler component of the X-ray emission. The complementary analyses of the X-ray and IR emission provide quantitative estimates of density and filling factors of the clumpy medium swept up by the SNR.

Temim, Tea↗
NASA NTRS2012

Infrared and X-Ray Spectroscopy of the Kes 75 Supernova Shell Characterizing the Dust and Gas Properties

We present deep Chandra observations and Spitzer Space Telescope infrared (IR) spectroscopy of the shell in the composite supernova remnant (SNR) Kes 75 (G29.7-0.3). The remnant is composed of a central pulsar wind nebula and a bright partial shell in the south that is visible at radio, IR, and X-ray wavelengths. The X-ray emission can be modeled by either a single thermal component with a temperature of approx 1.5 keV, or with two thermal components with temperatures of 1.5 and 0.2 keY. Previous studies suggest that the hot component may originate from reverse-shocked SN ejecta. However, our new analysis shows no definitive evidence for enhanced abundances of Si, S, Ar, Mg, and Fe, as expected from supernova (SN) ejecta, or for the IR spectral signatures characteristic of confirmed SN condensed dust, thus favoring a circumstellar or interstellar origin for the X-ray and IR emission. The X-ray and IR emission in the shell are spatially correlated, suggesting that the dust particles are collisionally heated by the X-ray emitting gas. The IR spectrum of the shell is dominated by continuum emission from dust with little, or no line emission. Modeling the IR spectrum shows that the dust is heated to a temperature of approx 140 K by a relatively dense, hot plasma, that also gives rise to the hot X-ray emission component. The density inferred from the IR emission is significantly higher than the density inferred from the X-ray models, suggesting a low filling factor for this X-ray emitting gas. The total mass of the warm dust component is at least 1.3 x 10(exp -2) Solar Mass, assuming no significant dust destruction has occurred in the shell. The IR data also reveal the presence of an additional plasma component with a cooler temperature, consistent with the 0.2 keV gas component. Our IR analysis therefore provides an independent verification of the cooler component of the X-ray emission. The complementary analyses of the X-ray and IR emission provide quantitative estimates of density and filling factors of the clumpy medium swept up by the SNR.

Temim, Tea↗
DOE OSTI2020

Materials Data on Ca(PIr)2 by Materials Project

Ca(IrP)2 crystallizes in the trigonal P3_221 space group. The structure is three-dimensional. Ca is bonded in a 11-coordinate geometry to five Ir and six equivalent P atoms. There are a spread of Ca–Ir bond distances ranging from 3.13–3.32 Å. There are a spread of Ca–P bond distances ranging from 3.02–3.17 Å. There are two inequivalent Ir sites. In the first Ir site, Ir is bonded in a 12-coordinate geometry to three equivalent Ca and four equivalent P atoms. There are two shorter (2.35 Å) and two longer (2.37 Å) Ir–P bond lengths. In the second Ir site, Ir is bonded in a 6-coordinate geometry to two equivalent Ca and four equivalent P atoms. There are two shorter (2.25 Å) and two longer (2.32 Å) Ir–P bond lengths. P is bonded to three equivalent Ca and four Ir atoms to form a mixture of distorted face, edge, and corner-sharing PCa3Ir4 pentagonal bipyramids.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on CeSi2Ir3 by Materials Project

CeIr3Si2 crystallizes in the orthorhombic Imma space group. The structure is three-dimensional. Ce is bonded in a 8-coordinate geometry to two equivalent Ce, twelve Ir, and six equivalent Si atoms. Both Ce–Ce bond lengths are 3.65 Å. There are a spread of Ce–Ir bond distances ranging from 3.15–3.56 Å. There are a spread of Ce–Si bond distances ranging from 3.17–3.36 Å. There are two inequivalent Ir sites. In the first Ir site, Ir is bonded in a 12-coordinate geometry to four equivalent Ce and four equivalent Si atoms. All Ir–Si bond lengths are 2.47 Å. In the second Ir site, Ir is bonded in a 4-coordinate geometry to four equivalent Ce and four equivalent Si atoms. There are two shorter (2.45 Å) and two longer (2.46 Å) Ir–Si bond lengths. Si is bonded in a 10-coordinate geometry to three equivalent Ce and six Ir atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on HoInIr by Materials Project

HoIrIn crystallizes in the hexagonal P-62m space group. The structure is three-dimensional. Ho is bonded in a 11-coordinate geometry to five Ir and six equivalent In atoms. There are four shorter (3.02 Å) and one longer (3.04 Å) Ho–Ir bond lengths. There are two shorter (3.21 Å) and four longer (3.32 Å) Ho–In bond lengths. There are two inequivalent Ir sites. In the first Ir site, Ir is bonded in a 9-coordinate geometry to three equivalent Ho and six equivalent In atoms. All Ir–In bond lengths are 2.77 Å. In the second Ir site, Ir is bonded in a 9-coordinate geometry to six equivalent Ho and three equivalent In atoms. All Ir–In bond lengths are 2.83 Å. In is bonded in a 10-coordinate geometry to six equivalent Ho and four Ir atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Mg4As6Ir7 by Materials Project

Mg4Ir7As6 crystallizes in the cubic Im-3m space group. The structure is three-dimensional. Mg is bonded to six equivalent Ir and six equivalent As atoms to form MgAs6Ir6 cuboctahedra that share corners with twelve equivalent MgAs6Ir6 cuboctahedra, corners with twelve equivalent IrMg4As4 cuboctahedra, edges with six equivalent IrMg4As4 cuboctahedra, faces with six equivalent MgAs6Ir6 cuboctahedra, and faces with two equivalent IrAs6 octahedra. All Mg–Ir bond lengths are 2.89 Å. All Mg–As bond lengths are 2.94 Å. There are two inequivalent Ir sites. In the first Ir site, Ir is bonded to six equivalent As atoms to form IrAs6 octahedra that share corners with twenty-four equivalent IrMg4As4 cuboctahedra and faces with eight equivalent MgAs6Ir6 cuboctahedra. All Ir–As bond lengths are 2.57 Å. In the second Ir site, Ir is bonded to four equivalent Mg and four equivalent As atoms to form distorted IrMg4As4 cuboctahedra that share corners with eight equivalent MgAs6Ir6 cuboctahedra, corners with twelve equivalent IrMg4As4 cuboctahedra, corners with four equivalent IrAs6 octahedra, edges with two equivalent IrMg4As4 cuboctahedra, edges with four equivalent MgAs6Ir6 cuboctahedra, and faces with four equivalent IrMg4As4 cuboctahedra. The corner-sharing octahedral tilt angles are 53°. All Ir–As bond lengths are 2.55 Å. As is bonded in a 9-coordinate geometry to four equivalent Mg and five Ir atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Yb4Ge6Ir7 by Materials Project

Yb4Ir7Ge6 crystallizes in the cubic Im-3m space group. The structure is three-dimensional. Yb is bonded to six equivalent Ir and six equivalent Ge atoms to form YbGe6Ir6 cuboctahedra that share corners with twelve equivalent YbGe6Ir6 cuboctahedra, faces with six equivalent YbGe6Ir6 cuboctahedra, and faces with two equivalent IrGe6 octahedra. All Yb–Ir bond lengths are 2.95 Å. All Yb–Ge bond lengths are 3.00 Å. There are two inequivalent Ir sites. In the first Ir site, Ir is bonded in a 12-coordinate geometry to four equivalent Yb and four equivalent Ge atoms. All Ir–Ge bond lengths are 2.59 Å. In the second Ir site, Ir is bonded to six equivalent Ge atoms to form IrGe6 octahedra that share faces with eight equivalent YbGe6Ir6 cuboctahedra. All Ir–Ge bond lengths are 2.64 Å. Ge is bonded in a 9-coordinate geometry to four equivalent Yb and five Ir atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on GdInIr by Materials Project

GdIrIn crystallizes in the hexagonal P-62m space group. The structure is three-dimensional. Gd is bonded in a 11-coordinate geometry to five Ir and six equivalent In atoms. There are four shorter (3.04 Å) and one longer (3.08 Å) Gd–Ir bond lengths. There are two shorter (3.25 Å) and four longer (3.36 Å) Gd–In bond lengths. There are two inequivalent Ir sites. In the first Ir site, Ir is bonded in a 9-coordinate geometry to three equivalent Gd and six equivalent In atoms. All Ir–In bond lengths are 2.78 Å. In the second Ir site, Ir is bonded in a 9-coordinate geometry to six equivalent Gd and three equivalent In atoms. All Ir–In bond lengths are 2.86 Å. In is bonded in a 10-coordinate geometry to six equivalent Gd and four Ir atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Mn4Ge6Ir7 by Materials Project

Mn4Ir7Ge6 crystallizes in the cubic Im-3m space group. The structure is three-dimensional. Mn is bonded to six equivalent Ir and six equivalent Ge atoms to form MnGe6Ir6 cuboctahedra that share corners with twelve equivalent MnGe6Ir6 cuboctahedra, faces with six equivalent MnGe6Ir6 cuboctahedra, and faces with two equivalent IrGe6 octahedra. All Mn–Ir bond lengths are 2.86 Å. All Mn–Ge bond lengths are 2.89 Å. There are two inequivalent Ir sites. In the first Ir site, Ir is bonded in a 12-coordinate geometry to four equivalent Mn and four equivalent Ge atoms. All Ir–Ge bond lengths are 2.56 Å. In the second Ir site, Ir is bonded to six equivalent Ge atoms to form IrGe6 octahedra that share faces with eight equivalent MnGe6Ir6 cuboctahedra. All Ir–Ge bond lengths are 2.47 Å. Ge is bonded in a 9-coordinate geometry to four equivalent Mn and five Ir atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on NpSnIr by Materials Project

NpIrSn crystallizes in the hexagonal P-62m space group. The structure is three-dimensional. Np is bonded in a 11-coordinate geometry to five Ir and six equivalent Sn atoms. There are four shorter (3.01 Å) and one longer (3.06 Å) Np–Ir bond lengths. There are two shorter (3.18 Å) and four longer (3.35 Å) Np–Sn bond lengths. There are two inequivalent Ir sites. In the first Ir site, Ir is bonded in a 9-coordinate geometry to six equivalent Np and three equivalent Sn atoms. All Ir–Sn bond lengths are 2.81 Å. In the second Ir site, Ir is bonded in a 9-coordinate geometry to three equivalent Np and six equivalent Sn atoms. All Ir–Sn bond lengths are 2.76 Å. Sn is bonded in a 10-coordinate geometry to six equivalent Np and four Ir atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on CeInIr by Materials Project

CeIrIn crystallizes in the hexagonal P-62m space group. The structure is three-dimensional. Ce is bonded in a 11-coordinate geometry to five Ir and six equivalent In atoms. There are four shorter (3.04 Å) and one longer (3.12 Å) Ce–Ir bond lengths. There are two shorter (3.24 Å) and four longer (3.38 Å) Ce–In bond lengths. There are two inequivalent Ir sites. In the first Ir site, Ir is bonded in a 9-coordinate geometry to three equivalent Ce and six equivalent In atoms. All Ir–In bond lengths are 2.77 Å. In the second Ir site, Ir is bonded in a 9-coordinate geometry to six equivalent Ce and three equivalent In atoms. All Ir–In bond lengths are 2.88 Å. In is bonded in a 10-coordinate geometry to six equivalent Ce and four Ir atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Sn7Ir5 by Materials Project

Ir5Sn7 crystallizes in the tetragonal I4mm space group. The structure is three-dimensional. there are two inequivalent Ir sites. In the first Ir site, Ir is bonded in a 7-coordinate geometry to seven Sn atoms. There are a spread of Ir–Sn bond distances ranging from 2.72–2.88 Å. In the second Ir site, Ir is bonded in a square pyramidal geometry to five Sn atoms. All Ir–Sn bond lengths are 2.63 Å. There are three inequivalent Sn sites. In the first Sn site, Sn is bonded in a 5-coordinate geometry to five Ir atoms. In the second Sn site, Sn is bonded to four equivalent Ir atoms to form distorted edge-sharing SnIr4 tetrahedra. In the third Sn site, Sn is bonded in a 5-coordinate geometry to five Ir atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on CeSnIr by Materials Project

CeIrSn crystallizes in the hexagonal P-62m space group. The structure is three-dimensional. Ce is bonded in a 11-coordinate geometry to five Ir and six equivalent Sn atoms. There are four shorter (3.05 Å) and one longer (3.10 Å) Ce–Ir bond lengths. There are two shorter (3.23 Å) and four longer (3.39 Å) Ce–Sn bond lengths. There are two inequivalent Ir sites. In the first Ir site, Ir is bonded in a 9-coordinate geometry to three equivalent Ce and six equivalent Sn atoms. All Ir–Sn bond lengths are 2.79 Å. In the second Ir site, Ir is bonded in a 9-coordinate geometry to six equivalent Ce and three equivalent Sn atoms. All Ir–Sn bond lengths are 2.85 Å. Sn is bonded in a 10-coordinate geometry to six equivalent Ce and four Ir atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on ZrSnIr by Materials Project

IrZrSn crystallizes in the hexagonal P-62m space group. The structure is three-dimensional. Zr is bonded in a 11-coordinate geometry to five Ir and six equivalent Sn atoms. There are one shorter (2.91 Å) and four longer (2.94 Å) Zr–Ir bond lengths. There are two shorter (3.12 Å) and four longer (3.19 Å) Zr–Sn bond lengths. There are two inequivalent Ir sites. In the first Ir site, Ir is bonded in a 9-coordinate geometry to three equivalent Zr and six equivalent Sn atoms. All Ir–Sn bond lengths are 2.72 Å. In the second Ir site, Ir is bonded in a 9-coordinate geometry to six equivalent Zr and three equivalent Sn atoms. All Ir–Sn bond lengths are 2.74 Å. Sn is bonded in a 10-coordinate geometry to six equivalent Zr and four Ir atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on SmInIr by Materials Project

SmIrIn crystallizes in the hexagonal P-62m space group. The structure is three-dimensional. Sm is bonded in a 11-coordinate geometry to five Ir and six equivalent In atoms. There are four shorter (3.06 Å) and one longer (3.09 Å) Sm–Ir bond lengths. There are two shorter (3.27 Å) and four longer (3.38 Å) Sm–In bond lengths. There are two inequivalent Ir sites. In the first Ir site, Ir is bonded in a 9-coordinate geometry to three equivalent Sm and six equivalent In atoms. All Ir–In bond lengths are 2.79 Å. In the second Ir site, Ir is bonded in a 9-coordinate geometry to six equivalent Sm and three equivalent In atoms. All Ir–In bond lengths are 2.88 Å. In is bonded in a 10-coordinate geometry to six equivalent Sm and four Ir atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Eu(PIr)2 by Materials Project

Eu(IrP)2 crystallizes in the trigonal P3_221 space group. The structure is three-dimensional. Eu is bonded in a 11-coordinate geometry to five Ir and six equivalent P atoms. There are a spread of Eu–Ir bond distances ranging from 3.18–3.35 Å. There are a spread of Eu–P bond distances ranging from 3.06–3.18 Å. There are two inequivalent Ir sites. In the first Ir site, Ir is bonded in a 12-coordinate geometry to three equivalent Eu and four equivalent P atoms. There are two shorter (2.35 Å) and two longer (2.40 Å) Ir–P bond lengths. In the second Ir site, Ir is bonded in a 6-coordinate geometry to two equivalent Eu and four equivalent P atoms. There are two shorter (2.27 Å) and two longer (2.33 Å) Ir–P bond lengths. P is bonded to three equivalent Eu and four Ir atoms to form a mixture of distorted face, edge, and corner-sharing PEu3Ir4 pentagonal bipyramids.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on TbInIr by Materials Project

TbIrIn crystallizes in the hexagonal P-62m space group. The structure is three-dimensional. Tb is bonded in a 11-coordinate geometry to five Ir and six equivalent In atoms. There are four shorter (3.03 Å) and one longer (3.06 Å) Tb–Ir bond lengths. There are two shorter (3.23 Å) and four longer (3.34 Å) Tb–In bond lengths. There are two inequivalent Ir sites. In the first Ir site, Ir is bonded in a 9-coordinate geometry to three equivalent Tb and six equivalent In atoms. All Ir–In bond lengths are 2.78 Å. In the second Ir site, Ir is bonded in a 9-coordinate geometry to six equivalent Tb and three equivalent In atoms. All Ir–In bond lengths are 2.84 Å. In is bonded in a 10-coordinate geometry to six equivalent Tb and four Ir atoms.

36 MATERIALS SCIENCE↗