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All sourcesNASA NTRSDOE OSTI
DOE OSTI2025

Strong Coupling of Iridium and Boron–Carbon-Nitride Support for Enhanced Acidic Water Oxidation

Supporting iridium (Ir)-based materials on stable and suitable substrates is an efficient strategy to improve their catalytic performance for the oxygen evolution reaction (OER) in harsh acidic environments. Herein, we report a series of Ir catalysts supported on boron–carbon-nitride (BCN), denoted as Ir/BCN. Detailed experiments combined with density functional theory calculations demonstrate strong interactions between Ir nanoparticles (NPs) and the BCN support, significantly contributing to the improved OER performance. Among the synthesized catalysts, the Ir/BCN-75 catalyst outperforms commercial Ir black and IrO 2 in both half-cell and proton exchange membrane water electrolysis (PEMWE) tests. Specially, the Ir/BCN-75 catalyst achieves a high current density of 2.94 A cm –2 at 1.9 V with a low Ir loading of 0.26 mg cm –2 in PEMWE measurements, exceeding most Ir-based catalysts reported to date. The BCN support interacts strongly with Ir, wherein Ir–N bonding directs the Ir NP growth and enhances electrocatalytic activity, while Ir–B bonding contributes to the stability of the Ir/BCN catalyst.

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

Subaru/HSC deep optical imaging of infrared sources in the AKARI North Ecliptic Pole-Wide field

In this work, we present a five-broad-band (grizy) photometric catalogue of Subaru/Hyper Suprime-Cam (HSC) optical imaging observations at around the North Ecliptic Pole (NEP) where the AKARI infrared (IR) satellite conducted a large survey (NEP-Wide survey). The observations cover almost all the NEP-Wide survey field down to the depth of 28.1, 26.8, 26.3, 25.5, and 25.0 mag (5σ) at grizy, respectively. The five-band HSC catalogue contains about 2.6 million objects, and 70 959 AKARI NEP-Wide counterpart sources are identified in the catalogue. We added existing supplementary catalogues from the u band to the far-IR band, and estimated photo-z for the AKARI-HSC sources. We achieved σΔz/(1 + zs) = 0.06 and an outlier rate of 13.4 per cent at z = 0.2–1.5. Using the spectral energy distribution (SED) template fitting, we classified the AKARI-HSC galaxies into four categories, namely quiescent, star-forming, Type1 active galactic nucleus (AGN), and Type2 AGN, in each redshift bin. Then, at z > 1, the mean SED of star-forming galaxies in mid-IR (3–10 μm) range is significantly different from that of spiral galaxies in the nearby Universe, indicating that many of star-forming galaxies at z > 1 contain a heat source capable of heating dust to temperatures that radiate thermal emission in the mid-IR range. Furthermore, we estimated the number fraction of AGNs (fAGN) in each bin of redshift and IR luminosity (L IR ), and examined the dependence of redshift and L IR . In log(L IR /L ⊙ ) = 11.0–14.0, the fAGN shows a significant increase with increasing redshift, regardless of the LIR bins. In contrast, the fAGN shows a slight increase against L IR at z < 1 and no increase with increasing L IR at z > 1.

79 ASTRONOMY AND ASTROPHYSICS↗
NASA NTRS1988

Iridium emissions from Hawaiian volcanoes

Particle and gas samples were collected at Mauna Loa volcano during and after its eruption in March and April, 1984 and at Kilauea volcano in 1983, 1984, and 1985 during various phases of its ongoing activity. In the last two Kilauea sampling missions, samples were collected during eruptive activity. The samples were collected using a filterpack system consisting of a Teflon particle filter followed by a series of 4 base-treated Whatman filters. The samples were analyzed by INAA for over 40 elements. As previously reported in the literature, Ir was first detected on particle filters at the Mauna Loa Observatory and later from non-erupting high temperature vents at Kilauea. Since that time Ir was found in samples collected at Kilauea and Mauna Loa during fountaining activity as well as after eruptive activity. Enrichment factors for Ir in the volcanic fumes range from 10,000 to 100,000 relative to BHVO. Charcoal impregnated filters following a particle filter were collected to see if a significant amount of the Ir was in the gas phase during sample collection. Iridium was found on charcoal filters collected close to the vent, no Ir was found on the charcoal filters. This indicates that all of the Ir is in particulate form very soon after its release. Ratios of Ir to F and Cl were calculated for the samples from Mauna Loa and Kilauea collected during fountaining activity. The implications for the KT Ir anomaly are still unclear though as Ir was not found at volcanoes other than those at Hawaii. Further investigations are needed at other volcanoes to ascertain if basaltic volcanoes other than hot spots have Ir enrichments in their fumes.

Finnegan, D. L.↗
NASA NTRS1989

Imaging infrared: Scene simulation, modeling, and real image tracking; Proceedings of the Meeting, Orlando, FL, Mar. 30, 31, 1989

Various papers on scene simulation, modeling, and real image tracking using IR imaging are presented. Individual topics addressed include: tactical IR scene generator, dynamic FLIR simulation in flight training research, high-speed dynamic scene simulation in UV to IR spectra, development of an IR sensor calibration facility, IR celestial background scene description, transmission measurement of optical components at cryogenic temperatures, diffraction model for a point-source generator, silhouette-based tracking for tactical IR systems, use of knowledge in electrooptical trackers, detection and classification of target formations in IR image sequences, SMPRAD: simplified three-dimensional cloud radiance model, IR target generator, recent advances in testing of thermal imagers, generic IR system models with dynamic image generation, modeling realistic target acquisition using IR sensors in multiple-observer scenarios, and novel concept of scene generation and comprehensive dynamic sensor test.

Triplett, Milton J.↗
NASA NTRS2009

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 ~ 1.5 keV, or with two thermal components with temperatures of 1.5 and 0.2 keV. 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 ill 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 ~ 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↗
NASA NTRS2017

Ionizing Radiation Affects Gene Expression in Mouse Skin and Bone

Future long-duration space exploration beyond low earth orbit will increase human exposure to space radiation and microgravity conditions as well as associated risks to skeletal health. In animal studies, radiation exposure (greater than 1 Gy) is associated with pathological changes in bone structure, enhanced bone resorption, reduced bone formation and decreased bone mineral density, which can lead to skeletal fragility. Definitive measurements and detection of bone loss typically require large and specialized equipment which can make their application to long duration space missions logistically challenging. Towards the goal of developing non-invasive and less complicated monitoring methods to predict astronauts' health during spaceflight, we examined whether radiation induced gene expression changes in skin may be predictive of the responses of skeletal tissue to radiation exposure. We examined oxidative stress and growth arrest pathways in mouse skin and long bones by measuring gene expression levels via quantitative polymerase chain reaction (qPCR) after exposure to total body irradiation (IR). To investigate the effects of irradiation on gene expression, we used skin and femora (cortical shaft) from the following treatment groups: control (normally loaded, sham-irradiated), and IR (0.5 Gy 56Fe 600 MeV/n and 0.5 Gy 1H 150 MeV/n), euthanized at one and 11 days post-irradiation (IR). To determine the extent of bone loss, tibiae were harvested and cancellous microarchitecture in the proximal tibia quantified ex vivo using microcomputed tomography (microCT). Statistical analysis was performed using Student's t-test. At one day post-IR, expression of FGF18 in skin was significantly greater (3.8X) than sham-irradiated controls, but did not differ at 11 days post IR. Expression levels of other genes associated with antioxidant response (Nfe2l2, FoxO3 and Sod1) and the cell cycle (Trp53, Cdkn1a, Gadd45g) did not significantly differ between the control and IR groups at either time point. Radiation exposure resulted in a 27.0% increase in FGF18-positive hair follicles at one day post-IR and returned to basal levels at 11 days post-IR. A similar trend was observed from FGF18 gene expression analysis of skin. In bone (femora), there was an increase in the expression of the pro-osteoclastogenic cytokine, MCP-1, one day after IR compared to non-irradiated controls. FGF18 expression in skin and MCP- 1 expression in bone were found to be positively correlated (P less than 0.002, r=0.8779). Further, microcomputed tomography analysis of tibia from these animals showed reduced cancellous bone volume (-9.9%) at 11 days post- IR. These results suggest that measurements of early radiation induced changes in FGF18 gene expression in skin may have value for predicting subsequent loss of cancellous bone mass. Further research may lead to the development of a relatively simple diagnostic tool for bone loss, with the advantage that hair follicles and skin are relatively easy to acquire from human subjects.

space radiation↗
DOE OSTI2020

Materials Data on Mg13Ir3 by Materials Project

Mg13Ir3 crystallizes in the trigonal R-3c space group. The structure is three-dimensional. there are four inequivalent Mg sites. In the first Mg site, Mg is bonded in a linear geometry to two equivalent Ir atoms. Both Mg–Ir bond lengths are 2.73 Å. In the second Mg site, Mg is bonded in a bent 150 degrees geometry to two equivalent Ir atoms. Both Mg–Ir bond lengths are 2.75 Å. In the third Mg site, Mg is bonded in a trigonal planar geometry to three equivalent Ir atoms. All Mg–Ir bond lengths are 2.77 Å. In the fourth Mg site, Mg is bonded in a 2-coordinate geometry to two equivalent Ir atoms. There are one shorter (2.71 Å) and one longer (2.83 Å) Mg–Ir bond lengths. Ir is bonded in a 9-coordinate geometry to nine Mg atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on LaTm(Ge2Ir)2 by Materials Project

TmLa(IrGe2)2 crystallizes in the orthorhombic Immm space group. The structure is three-dimensional. Tm is bonded in a 8-coordinate geometry to six equivalent Ir and nine Ge atoms. There are two shorter (3.23 Å) and four longer (3.27 Å) Tm–Ir bond lengths. There are a spread of Tm–Ge bond distances ranging from 2.97–3.49 Å. La is bonded in a 8-coordinate geometry to four equivalent Ir and ten Ge atoms. All La–Ir bond lengths are 3.26 Å. There are a spread of La–Ge bond distances ranging from 3.32–3.44 Å. Ir is bonded in a 10-coordinate geometry to three equivalent Tm, two equivalent La, and five Ge atoms. There are a spread of Ir–Ge bond distances ranging from 2.49–2.60 Å. There are three inequivalent Ge sites. In the first Ge site, Ge is bonded in a 8-coordinate geometry to three equivalent Tm, one La, three equivalent Ir, and one Ge atom. The Ge–Ge bond length is 2.70 Å. In the second Ge site, Ge is bonded in a 2-coordinate geometry to one Tm, four equivalent La, and two equivalent Ir atoms. In the third Ge site, Ge is bonded in a 9-coordinate geometry to two equivalent Tm, four equivalent La, two equivalent Ir, and one Ge atom. The Ge–Ge bond length is 2.60 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on HoGe2Ir by Materials Project

HoIrGe2 crystallizes in the orthorhombic Immm space group. The structure is three-dimensional. there are two inequivalent Ho sites. In the first Ho site, Ho is bonded in a 8-coordinate geometry to six equivalent Ir and nine Ge atoms. There are four shorter (3.23 Å) and two longer (3.29 Å) Ho–Ir bond lengths. There are a spread of Ho–Ge bond distances ranging from 2.95–3.51 Å. In the second Ho site, Ho is bonded in a 8-coordinate geometry to four equivalent Ir and ten Ge atoms. All Ho–Ir bond lengths are 3.17 Å. There are a spread of Ho–Ge bond distances ranging from 3.25–3.41 Å. Ir is bonded in a 10-coordinate geometry to five Ho and five Ge atoms. There are a spread of Ir–Ge bond distances ranging from 2.47–2.63 Å. There are three inequivalent Ge sites. In the first Ge site, Ge is bonded in a 8-coordinate geometry to four Ho, three equivalent Ir, and one Ge atom. The Ge–Ge bond length is 2.72 Å. In the second Ge site, Ge is bonded in a 9-coordinate geometry to six Ho, two equivalent Ir, and one Ge atom. The Ge–Ge bond length is 2.48 Å. In the third Ge site, Ge is bonded in a 2-coordinate geometry to five Ho and two equivalent Ir atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on ErGe2Ir by Materials Project

ErIrGe2 crystallizes in the orthorhombic Immm space group. The structure is three-dimensional. there are two inequivalent Er sites. In the first Er site, Er is bonded in a 12-coordinate geometry to six equivalent Ir and nine Ge atoms. There are four shorter (3.23 Å) and two longer (3.29 Å) Er–Ir bond lengths. There are a spread of Er–Ge bond distances ranging from 2.94–3.51 Å. In the second Er site, Er is bonded in a 8-coordinate geometry to four equivalent Ir and ten Ge atoms. All Er–Ir bond lengths are 3.16 Å. There are a spread of Er–Ge bond distances ranging from 3.23–3.41 Å. Ir is bonded in a 10-coordinate geometry to five Er and five Ge atoms. There are a spread of Ir–Ge bond distances ranging from 2.47–2.62 Å. There are three inequivalent Ge sites. In the first Ge site, Ge is bonded in a 8-coordinate geometry to four Er, three equivalent Ir, and one Ge atom. The Ge–Ge bond length is 2.71 Å. In the second Ge site, Ge is bonded in a 9-coordinate geometry to six Er, two equivalent Ir, and one Ge atom. The Ge–Ge bond length is 2.48 Å. In the third Ge site, Ge is bonded in a 2-coordinate geometry to five Er and two equivalent Ir atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on TbGe2Ir by Materials Project

TbIrGe2 crystallizes in the orthorhombic Immm space group. The structure is three-dimensional. there are two inequivalent Tb sites. In the first Tb site, Tb is bonded in a 8-coordinate geometry to six equivalent Ir and nine Ge atoms. There are four shorter (3.25 Å) and two longer (3.28 Å) Tb–Ir bond lengths. There are a spread of Tb–Ge bond distances ranging from 2.96–3.51 Å. In the second Tb site, Tb is bonded in a 8-coordinate geometry to four equivalent Ir and ten Ge atoms. All Tb–Ir bond lengths are 3.19 Å. There are a spread of Tb–Ge bond distances ranging from 3.27–3.42 Å. Ir is bonded in a 10-coordinate geometry to five Tb and five Ge atoms. There are a spread of Ir–Ge bond distances ranging from 2.48–2.64 Å. There are three inequivalent Ge sites. In the first Ge site, Ge is bonded in a 8-coordinate geometry to four Tb, three equivalent Ir, and one Ge atom. The Ge–Ge bond length is 2.74 Å. In the second Ge site, Ge is bonded in a 9-coordinate geometry to six Tb, two equivalent Ir, and one Ge atom. The Ge–Ge bond length is 2.49 Å. In the third Ge site, Ge is bonded in a 2-coordinate geometry to five Tb and two equivalent Ir atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Nd5Ir3 by Materials Project

Nd5Ir3 crystallizes in the tetragonal P4/ncc space group. The structure is three-dimensional. there are two inequivalent Nd sites. In the first Nd site, Nd is bonded to five Ir atoms to form distorted NdIr5 trigonal bipyramids that share corners with four equivalent NdIr4 tetrahedra, corners with eleven equivalent NdIr5 trigonal bipyramids, an edgeedge with one NdIr4 tetrahedra, edges with six equivalent NdIr5 trigonal bipyramids, and faces with two equivalent NdIr5 trigonal bipyramids. There are a spread of Nd–Ir bond distances ranging from 2.98–3.28 Å. In the second Nd site, Nd is bonded to four equivalent Ir atoms to form NdIr4 tetrahedra that share corners with sixteen equivalent NdIr5 trigonal bipyramids, edges with two equivalent NdIr4 tetrahedra, and edges with four equivalent NdIr5 trigonal bipyramids. All Nd–Ir bond lengths are 2.95 Å. There are two inequivalent Ir sites. In the first Ir site, Ir is bonded in a 8-coordinate geometry to eight Nd atoms. In the second Ir site, Ir is bonded in a 8-coordinate geometry to eight equivalent Nd atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on NdGe2Ir by Materials Project

NdIrGe2 crystallizes in the orthorhombic Immm space group. The structure is three-dimensional. there are two inequivalent Nd sites. In the first Nd site, Nd is bonded in a 8-coordinate geometry to six equivalent Ir and nine Ge atoms. There are two shorter (3.28 Å) and four longer (3.31 Å) Nd–Ir bond lengths. There are a spread of Nd–Ge bond distances ranging from 3.03–3.50 Å. In the second Nd site, Nd is bonded in a 8-coordinate geometry to four equivalent Ir and ten Ge atoms. All Nd–Ir bond lengths are 3.25 Å. There are a spread of Nd–Ge bond distances ranging from 3.33–3.46 Å. Ir is bonded in a 10-coordinate geometry to five Nd and five Ge atoms. There are a spread of Ir–Ge bond distances ranging from 2.49–2.68 Å. There are three inequivalent Ge sites. In the first Ge site, Ge is bonded in a 9-coordinate geometry to six Nd, two equivalent Ir, and one Ge atom. The Ge–Ge bond length is 2.53 Å. In the second Ge site, Ge is bonded in a 2-coordinate geometry to five Nd and two equivalent Ir atoms. In the third Ge site, Ge is bonded in a 8-coordinate geometry to four Nd, three equivalent Ir, and one Ge atom. The Ge–Ge bond length is 2.78 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Mg3Ir by Materials Project

Mg3Ir crystallizes in the hexagonal P6_3cm space group. The structure is three-dimensional. there are four inequivalent Mg sites. In the first Mg site, Mg is bonded in a 2-coordinate geometry to two equivalent Ir atoms. There are one shorter (2.74 Å) and one longer (2.77 Å) Mg–Ir bond lengths. In the second Mg site, Mg is bonded in a trigonal planar geometry to three equivalent Ir atoms. All Mg–Ir bond lengths are 2.69 Å. In the third Mg site, Mg is bonded in a distorted trigonal planar geometry to three equivalent Ir atoms. All Mg–Ir bond lengths are 2.66 Å. In the fourth Mg site, Mg is bonded in a distorted trigonal planar geometry to three equivalent Ir atoms. There are one shorter (2.74 Å) and two longer (2.83 Å) Mg–Ir bond lengths. Ir is bonded in a 8-coordinate geometry to eight Mg atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on ZrIr by Materials Project

ZrIr crystallizes in the orthorhombic Cmcm space group. The structure is three-dimensional. there are two inequivalent Zr sites. In the first Zr site, Zr is bonded in a 5-coordinate geometry to seven Ir atoms. There are a spread of Zr–Ir bond distances ranging from 2.71–3.24 Å. In the second Zr site, Zr is bonded in a body-centered cubic geometry to eight Ir atoms. There are a spread of Zr–Ir bond distances ranging from 2.73–2.90 Å. There are two inequivalent Ir sites. In the first Ir site, Ir is bonded in a 8-coordinate geometry to eight Zr atoms. In the second Ir site, Ir is bonded in a 7-coordinate geometry to seven Zr atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on TaIr by Materials Project

IrTa is Tetraauricupride-like structured and crystallizes in the orthorhombic Pmma space group. The structure is three-dimensional. there are two inequivalent Ta sites. In the first Ta site, Ta is bonded in a 12-coordinate geometry to eight Ir atoms. There are a spread of Ta–Ir bond distances ranging from 2.79–2.87 Å. In the second Ta site, Ta is bonded in a 12-coordinate geometry to eight Ir atoms. There are a spread of Ta–Ir bond distances ranging from 2.77–2.84 Å. There are two inequivalent Ir sites. In the first Ir site, Ir is bonded in a 12-coordinate geometry to eight Ta atoms. In the second Ir site, Ir is bonded in a 12-coordinate geometry to eight Ta atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on YGe2Ir by Materials Project

YIrGe2 crystallizes in the orthorhombic Immm space group. The structure is three-dimensional. there are two inequivalent Y sites. In the first Y site, Y is bonded in a 8-coordinate geometry to six equivalent Ir and nine Ge atoms. There are four shorter (3.25 Å) and two longer (3.28 Å) Y–Ir bond lengths. There are a spread of Y–Ge bond distances ranging from 2.96–3.50 Å. In the second Y site, Y is bonded in a 8-coordinate geometry to four equivalent Ir and ten Ge atoms. All Y–Ir bond lengths are 3.19 Å. There are a spread of Y–Ge bond distances ranging from 3.27–3.41 Å. Ir is bonded in a 10-coordinate geometry to five Y and five Ge atoms. There are a spread of Ir–Ge bond distances ranging from 2.48–2.63 Å. There are three inequivalent Ge sites. In the first Ge site, Ge is bonded in a 9-coordinate geometry to six Y, two equivalent Ir, and one Ge atom. The Ge–Ge bond length is 2.49 Å. In the second Ge site, Ge is bonded in a 8-coordinate geometry to four Y, three equivalent Ir, and one Ge atom. The Ge–Ge bond length is 2.73 Å. In the third Ge site, Ge is bonded in a 2-coordinate geometry to five Y and two equivalent Ir atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Tm5Ir3 by Materials Project

Tm5Ir3 crystallizes in the tetragonal P4/ncc space group. The structure is three-dimensional. there are two inequivalent Tm sites. In the first Tm site, Tm is bonded to five Ir atoms to form distorted TmIr5 trigonal bipyramids that share corners with four equivalent TmIr4 tetrahedra, corners with eleven equivalent TmIr5 trigonal bipyramids, an edgeedge with one TmIr4 tetrahedra, edges with six equivalent TmIr5 trigonal bipyramids, and faces with two equivalent TmIr5 trigonal bipyramids. There are a spread of Tm–Ir bond distances ranging from 2.86–3.09 Å. In the second Tm site, Tm is bonded to four equivalent Ir atoms to form TmIr4 tetrahedra that share corners with sixteen equivalent TmIr5 trigonal bipyramids, edges with two equivalent TmIr4 tetrahedra, and edges with four equivalent TmIr5 trigonal bipyramids. All Tm–Ir bond lengths are 2.82 Å. There are two inequivalent Ir sites. In the first Ir site, Ir is bonded in a 8-coordinate geometry to eight Tm atoms. In the second Ir site, Ir is bonded in a 8-coordinate geometry to eight equivalent Tm atoms.

36 MATERIALS SCIENCE↗