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At least 19 records
All sourcesNASA NTRSDOE OSTI
DOE OSTI2023

Hydrogen Storage with Aluminum Formate, ALF: Experimental, Computational, and Technoeconomic Studies

Long-duration storage of hydrogen is necessary for coupling renewable H 2 with stationary fuel cell power applications. In this work, aluminum formate (ALF), which adopts the ReO 3 -type structure, is shown to have remarkable H 2 storage performance at non-cryogenic (>120 K) temperatures and low pressures. The most promising performance of ALF is found between 120 K and 160 K and at 10 bar to 20 bar. The study illustrates H 2 adsorption performance of ALF over the 77 K to 296 K temperature range using gas isotherms, in situ neutron powder diffraction, and DFT calculations, as well as technoeconomic analysis (TEA), illustrating ALF’s competitive performance for long-duration storage versus compressed hydrogen and leading metal–organic frameworks. In the TEA, it is shown that ALF’s storage capacity, when combined with a temperature/pressure swing process, has advantages versus compressed H 2 at a fraction of the pressure (15 bar versus 350 bar). In conclusion, given ALF’s performance in the 10 bar to 20 bar regime under moderate cooling, it is particularly promising for use in safe storage systems serving fuel cells.

08 HYDROGEN↗
DOE OSTI2025

Hydrogen Storage with Aluminum Formate, ALF: Experimental, Computational, and Technoeconomic Studies

Long-duration storage of hydrogen is necessary for coupling renewable H2 with stationary fuel cell power applications. In this presentation, I will discuss how aluminum formate, Al(HCOO)3 (ALF), which adopts an ReO3-type structure, is shown to have remarkable H2 storage performance at non-cryogenic (> 120 K) temperatures and low pressures. The most promising performance of ALF is found between 120 K and 160 K and at 10 bar to 20 bar. The talk will cover and illustrate the H2 adsorption performance of ALF over the 77 K to 296 K temperature range using gas isotherms, in situ neutron powder diffraction, and DFT calculations, as well as technoeconomic analysis (TEA), illustrating ALF’s competitive performance for long-duration storage versus compressed hydrogen and leading metal–organic frameworks. In the TEA, it is shown that ALF’s storage capacity, when combined with a temperature/pressure swing process, has advantages versus compressed H2 at a fraction of the pressure (15 bar versus 350 bar). Given ALF’s performance in the 10 bar to 20 bar regime under moderate cooling, it is particularly promising for use in safe storage systems serving fuel cells, and is currently the only MOF that works in this moderate temperature range/ low pressure regime to be cost competitive with compressed H2 gas for large scale H2 storage.[1]

Chemistry↗
DOE OSTI2021

Comparison of AlF 3 thin films grown by thermal and plasma enhanced atomic layer deposition

Films of aluminum fluoride (AlF 3 ) deposited by thermal and plasma enhanced atomic layer deposition (PEALD) have been compared using in situ multiwavelength ellipsometry (MWE) and monochromatic x-ray photoelectron spectroscopy (XPS). The AlF 3 films were grown using cyclic exposures of trimethylaluminum, hydrogen fluoride, and H radicals from a remote H 2 inductively coupled plasma. Films were characterized in situ using MWE and XPS for growth rate, film composition, and impurity incorporation. The MWE showed a growth rate of 1.1 and 0.7 Å per cycle, at 100 °C, for thermal and plasma enhanced ALD AlF 3 films, respectively. Carbon incorporation was below the XPS detection limit. The plasma enhanced ALD AlF 3 film showed the presence of Al-Al chemical states, in the Al 2p scans, suggesting the presence of Al-rich clusters with a concentration of 14%. The Al-rich clusters are thought to originate during the hydrogen plasma step of the PEALD process. Finally, the Al-rich clusters were not detected in thermal ALD AlF 3 films using the same precursors and substrate temperature.

36 MATERIALS SCIENCE↗
NASA NTRS1994

Exotic fluoride molecules in IRC +10216: Confirmation of AlF and searches for MgF and CaF

Three new rotational transitions of aluminum fluoride (AlF) at 0.8 and 1.2 mm have been observed. The J = 10-9, J = 8-7, and J = 7-6 lines of AlF at 230, 263, and 329 GHz, respectively, were seen toward IRC +10216 using the Caltech Submillimter Observatory (CSO). Combined with the earlier data obtained for this species at IRAM at 2 and 3 mm, these measurements confirm the presence of the metal halide in this carbon-rich circumstellar shell. Analysis of the CSO and IRAM data suggests that AlF arises from a source with a diameter of theta(sub s) approximately = 5-10 sec and hence is present chiefly in the inner envelope of IRC +10216. In this region, the molecule has a column density of (0.3-1.1) x 10(exp 15)/sq cm, which indicates a fractional abundance of at least approximately 10(exp -9), relative to H2. Searches for the metal fluoride species CaF and MgF have also been conducted toward IRC +10216, but with negative results. The column density upper limits for MgF and CaF are N(sub tot) less than (1-4) x 10(exp 14)/sq cm. Relative abundances of these metal fluoride molecules can be understood in terms of chemical thermodynamic equilibrium. The presence of AlF in IRC +10216 also indicates that large quantities of fluorine must be present in the inner stellar envelope, suggesting that this element may be produced not primarily in explosive nucleosynthesis but rather in helium shell flashes, as indicated also by HF spectroscopy of red giant stars.

Ziurys, L. M.↗
NASA NTRS1988

Theoretical studies of AlF, AlCl, and AlBr

Spectroscopic constants have been obtained for the lowest six singlet and lowest five triplet states of AlF and AlCl. The results suggest that the correct ordering of the triplet manifold in these molecules is: a 3Pi, b 3Sigma(+), c 3Sigma(+), d 3Pi, and e 3Delta. Radiative lifetimes have been determined for the excited states, and the A 1Pi to X 1Sigma(+) transition in AlF, AlCl, and AlBr has been examined in detail. A-X transition moment functions, Einstein coefficients, and A 1Pi vibrational lifetimes have been obtained for AlF and AlCl.

Langhoff, Stephen R.↗
NASA NTRSDate not supplied

Environmental and Polarization Characterizations of E-Beam Plasma-Based AlF 3 -Passivated Aluminum Mirrors for Astronomical Telescopes

Astronomical space telescopes to study astrophysical phenomena from the far ultraviolet (FUV) to the near infrared (NIR) will require mirror coatings with high reflectance over this entire spectral region. While coatings for the optical and NIR part of the spectrum are fairly well developed with proven performance, the FUV range has presented significant challenges, particularly below 120nm. Recent developments in electron-beam (e-Beam) generated plasma treatment in a SF 6 environments has enabled the effective passivation of aluminum (Al) coatings for applications in the FUV, by native oxide removal and the formation of a AlF 3 passivation layer which could be tuned to any desired AlF 3 thickness. These results have been produced through a collaboration between the Goddard Space Flight Center (GSFC) and the Naval Research Laboratory (NRL). The passivation experiments have been carried out using the Large Area Plasma Processing System (LAPPS) at NRL using bare aluminum samples and provided by the coating group at GSFC. This novel procedure has demonstrated improved Al mirrors with state-of-the-art FUV reflectivity (e.g. R=91% at 121.6nm). In this paper, we will be reporting on environmental testing, micro-roughness, as well as polarization studies of these E-beam treated samples. These characterizations are being done in order to advance the Technology Readiness Level (TRL) for these Al+AlF 3 mirror coatings produced at LAPPS. The ultimate goal is to demonstrate the promise of using this coating technology to deliver reflectance performance plus stability and uniformity over a large area for a future IR/O/UV space telescope observatory.

FUV reflectance↗
DOE OSTI2021

Borderline first-order magnetic phase transition in AlFe 2 B 2

The thermal evolution of lattice parameters coupled with heat capacity data provide insight into tailorable magnetism-structure attributes in the orthorhombic compound AlFe 2 B 2 that was synthesized with and without small additions of gallium. Temperature-dependent X-ray powder diffraction experiments conducted through the magnetic phase transition reveal that the a- and b-parameters of both samples increase with increasing temperature while the c-parameter decreases. While a weak volumetric thermal expansion is noted over a range of temperatures well below and above the magnetic phase transition, anomalous behavior was observed within the phase transition region itself to reveal a magnetostructural phase transition with borderline first-order character in the Ga-modified sample but of more second-order character in the Ga-free sample. It is established that the nearest-neighbor Fe-Fe interatomic distance within the (ab)-plane plays a dominant role in influencing the magneto-functional response of these compounds. The magnetocaloric properties are discussed in the context of temperature-induced changes of the interatomic bonding that are influenced by the hypothesized presence of iron antisite defects in the AlFe 2 B 2 lattice.

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

Materials Data on AlFe by Materials Project

FeAl is Tetraauricupride structured and crystallizes in the cubic Pm-3m space group. The structure is three-dimensional. Fe is bonded in a body-centered cubic geometry to eight equivalent Al atoms. All Fe–Al bond lengths are 2.49 Å. Al is bonded in a body-centered cubic geometry to eight equivalent Fe atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on AlFe by Materials Project

FeAl crystallizes in the hexagonal P6/mmm space group. The structure is one-dimensional and consists of one FeAl ribbon oriented in the (0, 0, 1) direction. Fe is bonded in a distorted linear geometry to two equivalent Al atoms. Both Fe–Al bond lengths are 2.45 Å. Al is bonded in a distorted linear geometry to two equivalent Fe atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Sc(AlFe)6 by Materials Project

Sc(FeAl)6 crystallizes in the orthorhombic Immm space group. The structure is three-dimensional. Sc is bonded in a 8-coordinate geometry to twelve Fe and eight Al atoms. There are four shorter (3.20 Å) and eight longer (3.25 Å) Sc–Fe bond lengths. There are a spread of Sc–Al bond distances ranging from 2.80–2.94 Å. There are two inequivalent Fe sites. In the first Fe site, Fe is bonded in a 12-coordinate geometry to two equivalent Sc, four Fe, and six Al atoms. There are two shorter (2.47 Å) and two longer (2.48 Å) Fe–Fe bond lengths. There are two shorter (2.51 Å) and four longer (2.57 Å) Fe–Al bond lengths. In the second Fe site, Fe is bonded in a 12-coordinate geometry to two equivalent Sc, four equivalent Fe, and six Al atoms. There are four shorter (2.56 Å) and two longer (2.59 Å) Fe–Al bond lengths. There are three inequivalent Al sites. In the first Al site, Al is bonded in a 10-coordinate geometry to one Sc, six Fe, and three Al atoms. There are one shorter (2.69 Å) and two longer (2.83 Å) Al–Al bond lengths. In the second Al site, Al is bonded in a 8-coordinate geometry to one Sc, six Fe, and one Al atom. The Al–Al bond length is 2.83 Å. In the third Al site, Al is bonded in a 6-coordinate geometry to two equivalent Sc, six Fe, and two equivalent Al atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Hf(AlFe)6 by Materials Project

Fe6Al6Hf crystallizes in the orthorhombic Immm space group. The structure is three-dimensional. Hf is bonded in a 8-coordinate geometry to twelve Fe and eight Al atoms. There are four shorter (3.19 Å) and eight longer (3.24 Å) Hf–Fe bond lengths. There are two shorter (2.82 Å) and six longer (2.93 Å) Hf–Al bond lengths. There are two inequivalent Fe sites. In the first Fe site, Fe is bonded in a 12-coordinate geometry to two equivalent Hf, four Fe, and six Al atoms. There are two shorter (2.47 Å) and two longer (2.48 Å) Fe–Fe bond lengths. There are two shorter (2.50 Å) and four longer (2.57 Å) Fe–Al bond lengths. In the second Fe site, Fe is bonded in a 12-coordinate geometry to two equivalent Hf, four equivalent Fe, and six Al atoms. There are a spread of Fe–Al bond distances ranging from 2.55–2.60 Å. There are three inequivalent Al sites. In the first Al site, Al is bonded in a 10-coordinate geometry to one Hf, six Fe, and three Al atoms. There are one shorter (2.67 Å) and two longer (2.83 Å) Al–Al bond lengths. In the second Al site, Al is bonded in a 8-coordinate geometry to one Hf, six Fe, and one Al atom. The Al–Al bond length is 2.78 Å. In the third Al site, Al is bonded in a 6-coordinate geometry to two equivalent Hf, six Fe, and two equivalent Al atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Pr(AlFe)6 by Materials Project

Pr(FeAl)6 crystallizes in the orthorhombic Immm space group. The structure is three-dimensional. Pr is bonded in a 8-coordinate geometry to twelve Fe and eight Al atoms. There are four shorter (3.26 Å) and eight longer (3.32 Å) Pr–Fe bond lengths. There are a spread of Pr–Al bond distances ranging from 2.93–3.07 Å. There are two inequivalent Fe sites. In the first Fe site, Fe is bonded to two equivalent Pr, four Fe, and six Al atoms to form a mixture of distorted face, edge, and corner-sharing FePr2Al6Fe4 cuboctahedra. There are two shorter (2.51 Å) and two longer (2.52 Å) Fe–Fe bond lengths. There are a spread of Fe–Al bond distances ranging from 2.53–2.64 Å. In the second Fe site, Fe is bonded to two equivalent Pr, four equivalent Fe, and six Al atoms to form a mixture of distorted face, edge, and corner-sharing FePr2Al6Fe4 cuboctahedra. There are a spread of Fe–Al bond distances ranging from 2.60–2.73 Å. There are three inequivalent Al sites. In the first Al site, Al is bonded in a 10-coordinate geometry to one Pr, six Fe, and three Al atoms. There are one shorter (2.65 Å) and two longer (2.82 Å) Al–Al bond lengths. In the second Al site, Al is bonded in a 7-coordinate geometry to one Pr, six Fe, and two equivalent Al atoms. Both Al–Al bond lengths are 2.96 Å. In the third Al site, Al is bonded in a 12-coordinate geometry to two equivalent Pr, six Fe, and four Al atoms.

36 MATERIALS SCIENCE↗
NASA NTRS1972

Design study of an air pump and integral lift engine ALF-504 using the Lycoming 502 core

Design studies were conducted for an integral lift fan engine utilizing the Lycoming 502 fan core with the final MQT power turbine. The fan is designed for a 12.5 bypass ratio and 1.25:1 pressure ratio, and provides supercharging for the core. Maximum sea level static thrust is 8370 pounds with a specific fuel consumption of 0.302 lb/hr-lb. The dry engine weight without starter is 1419 pounds including full-length duct and sound-attenuating rings. The engine envelope including duct treatment but not localized accessory protrusion is 53.25 inches in diameter and 59.2 inches long from exhaust nozzle exit to fan inlet flange. Detailed analyses include fan aerodynamics, fan and reduction gear mechanical design, fan dynamic analysis, engine noise analysis, engine performance, and weight analysis.

Rauch, D.↗
DOE OSTI2021

Multifunctional Separator Allows Stable Cycling of Potassium Metal Anodes and of Potassium Metal Batteries

Here, this is the first report of a multifunctional separator for potassium-metal batteries (KMBs). Here, double-coated tape-cast microscale AlF 3 on polypropylene (AlF 3 @PP) yields state-of-the-art electrochemical performance: symmetric cells are stable after 1000 cycles (2000 h) at 0.5 mA cm –2 and 0.5 mAh cm –2 , with 0.042 V overpotential. Stability is maintained at 5.0 mA cm –2 for 600 cycles (240 h), with 0.138 V overpotential. Postcycled plated surface is dendrite-free, while stripped surface contains smooth solid electrolyte interphase (SEI). Conventional PP cells fail rapidly, with dendrites at plating, and “dead metal” and SEI clumps at stripping. Potassium hexacyanoferrate(III) cathode KMBs with AlF 3 @PP display enhanced capacity retention (91% at 100 cycles vs 58%). AlF 3 partially reacts with K to form an artificial SEI containing KF, AlF 3 , and Al 2 O 3 phases. The AlF 3 @PP promotes complete electrolyte wetting and enhances uptake, improves ion conductivity, and increases ion transference number. The higher of K + transference number is ascribed to the strong interaction between AlF 3 and FSI – anions, as revealed through 19 F NMR. The enhancement in wetting and performance is general, being demonstrated with ester- and ether-based solvents, with K-, Na-, or Li- salts, and with different commercial separators. In full batteries, AlF 3 prevents Fe crossover and cycling-induced cathode pulverization.

NMB↗
NASA NTRSDate not supplied

Exposure of Highly Reflective Far-Ultraviolet Coatings to LEO Environment for TRL Advancement for the Habitable Worlds Observatory

Over the past several years, our team at the NASA Goddard Space Flight Center (GSFC), in collaboration with the Jet Propulsion Laboratory (JPL) and the Naval Research Laboratory (NRL), have developed several new protected Al coating technologies with improved Far-Ultraviolet (FUV) reflectance performance and more robust environmental stability. These include Al protected with lithium-based fluoride (LiF) coatings such as hot deposited LiF (eLiF), XeF 2 -passivated LiF coatings (XeLiF), Li 3 AlF 6 overcoats, AlF 3 (plasma passivated), and XeF 2 passivated MgF 2 coatings (XeMgF 2 ). However, despite these developments, relatively little experimental information exists regarding the long-term stability of these coatings after simultaneous exposure to the Low Earth Orbit (LEO) environment. To evaluate their environmental durability and advance their Technology Readiness Level (TRL), representative samples of these coating technologies, Al+XeLiF, Al+eLiF, Al+Li 3 AlF 6 , Al+AlF 3 , Al+XeMgF 2 , and bare Al as reference samples, were flown onboard the International Space Station (ISS) as part of the Materials International Space Station Experiment 20 (MISSE-20). The MISSE platform is operated by Aegis Aerospace for relatively long-duration (e.g. 6 months) external exposure experiments in a space environment. The coatings were deposited on ULE and Zerodur substrates, and witness samples deposited on the same coatings runs, but on glass slides were left on Earth as control. A subset of the flight samples were fitted with MgF 2 windows to reduce direct exposure to atomic oxygen (AO) and charged particles, and still let through UV and other types of radiation on these samples. After approximately 6 months of exposure in the forward-facing (RAM) direction, the samples were returned to Earth and characterized by performing FUV/NUV/VIS/NIR reflectance measurements to quantify degradation, spectroscopic ellipsometry to evaluate coating thickness and optical constants, atomic force microscopy (AFM) to quantify surface roughness evolution during the flight in the ISS. The MgF 2 protective windows were also analyzed through FUV transmission measurements. Comparison with the witness samples left on the ground and with the flown bare Al samples (with just the naturally occurring Al 2 O 3 layer) provided a quantitative assessment of coating thickness variations, optical performance degradation, and morphological changes induced by prolonged exposure to the LEO environment.

Far Ultraviolet (FUV)↗