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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.

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At least 181 records · Page 10
All sourcesNASA NTRSDOE OSTI
DOE OSTI2020

Materials Data on Hg2Br2N by Materials Project

Hg2NBr2 crystallizes in the monoclinic C2 space group. The structure is three-dimensional. there are three inequivalent Hg2+ sites. In the first Hg2+ site, Hg2+ is bonded to five Br1- atoms to form corner-sharing HgBr5 trigonal bipyramids. There are a spread of Hg–Br bond distances ranging from 2.63–3.12 Å. In the second Hg2+ site, Hg2+ is bonded in a distorted linear geometry to two equivalent N2- and four Br1- atoms. Both Hg–N bond lengths are 2.08 Å. There are a spread of Hg–Br bond distances ranging from 3.26–3.62 Å. In the third Hg2+ site, Hg2+ is bonded in a distorted linear geometry to two equivalent N2- and four Br1- atoms. Both Hg–N bond lengths are 2.08 Å. There are a spread of Hg–Br bond distances ranging from 3.26–3.62 Å. N2- is bonded in a trigonal planar geometry to three Hg2+ atoms. There are three inequivalent Br1- sites. In the first Br1- site, Br1- is bonded to eight Hg2+ atoms to form distorted corner-sharing BrHg8 hexagonal bipyramids. In the second Br1- site, Br1- is bonded in a 1-coordinate geometry to three Hg2+ atoms. In the third Br1- site, Br1- is bonded in a 1-coordinate geometry to three Hg2+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on PH4IN4 by Materials Project

(H2)2PN4I crystallizes in the tetragonal P4/nbm space group. The structure is one-dimensional and consists of eight hydrogen molecules and four PN4I ribbons oriented in the (0, 0, 1) direction. In each PN4I ribbon, P5+ is bonded in a hexagonal planar geometry to four equivalent N2- and two equivalent I1- atoms. All P–N bond lengths are 2.46 Å. Both P–I bond lengths are 2.75 Å. N2- is bonded in a 2-coordinate geometry to one P5+ and one N2- atom. The N–N bond length is 1.13 Å. I1- is bonded in a linear geometry to two equivalent P5+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Mg(BrN3)2 by Materials Project

MgN6(Br)2 crystallizes in the cubic Fm-3m space group. The structure is three-dimensional and consists of eight hydrobromic acid molecules and one MgN6 framework. In the MgN6 framework, Mg2+ is bonded in an octahedral geometry to six equivalent N2- atoms. All Mg–N bond lengths are 2.81 Å. N2- is bonded in a 5-coordinate geometry to one Mg2+ and four equivalent N2- atoms. All N–N bond lengths are 1.71 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Tm2N3 by Materials Project

Tm2N3 is Corundum-like structured and crystallizes in the cubic Ia-3 space group. The structure is three-dimensional. there are two inequivalent Tm3+ sites. In the first Tm3+ site, Tm3+ is bonded to six equivalent N2- atoms to form a mixture of distorted edge and corner-sharing TmN6 octahedra. The corner-sharing octahedral tilt angles are 57°. All Tm–N bond lengths are 2.31 Å. In the second Tm3+ site, Tm3+ is bonded to six equivalent N2- atoms to form a mixture of distorted edge and corner-sharing TmN6 octahedra. The corner-sharing octahedra tilt angles range from 56–57°. There are a spread of Tm–N bond distances ranging from 2.29–2.36 Å. N2- is bonded to four Tm3+ atoms to form a mixture of distorted edge and corner-sharing NTm4 tetrahedra.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Ho2N3 by Materials Project

Ho2N3 is Corundum-like structured and crystallizes in the cubic Ia-3 space group. The structure is three-dimensional. there are two inequivalent Ho3+ sites. In the first Ho3+ site, Ho3+ is bonded to six equivalent N2- atoms to form a mixture of distorted edge and corner-sharing HoN6 octahedra. The corner-sharing octahedra tilt angles range from 56–58°. There are a spread of Ho–N bond distances ranging from 2.32–2.38 Å. In the second Ho3+ site, Ho3+ is bonded to six equivalent N2- atoms to form a mixture of distorted edge and corner-sharing HoN6 octahedra. The corner-sharing octahedral tilt angles are 58°. All Ho–N bond lengths are 2.34 Å. N2- is bonded to four Ho3+ atoms to form a mixture of distorted edge and corner-sharing NHo4 tetrahedra.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on RbPNO2 by Materials Project

RbPNO2 crystallizes in the trigonal R-3 space group. The structure is three-dimensional. Rb1+ is bonded in a 9-coordinate geometry to two equivalent N2- and seven O2- atoms. There are one shorter (3.13 Å) and one longer (3.30 Å) Rb–N bond lengths. There are a spread of Rb–O bond distances ranging from 2.90–3.53 Å. P5+ is bonded to two equivalent N2- and two O2- atoms to form corner-sharing PN2O2 tetrahedra. There is one shorter (1.66 Å) and one longer (1.67 Å) P–N bond length. There is one shorter (1.51 Å) and one longer (1.53 Å) P–O bond length. N2- is bonded in a distorted bent 120 degrees geometry to two equivalent Rb1+ and two equivalent P5+ atoms. There are two inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted single-bond geometry to three equivalent Rb1+ and one P5+ atom. In the second O2- site, O2- is bonded in a single-bond geometry to four equivalent Rb1+ and one P5+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on CoAg(N3O4)2 by Materials Project

CoAgN2(NO2)4 crystallizes in the tetragonal P4/nnc space group. The structure is one-dimensional and consists of eight nitrous acid molecules and two CoAgN2 ribbons oriented in the (0, 0, 1) direction. In each CoAgN2 ribbon, Co3+ is bonded in a linear geometry to two equivalent N2+ atoms. Both Co–N bond lengths are 1.67 Å. Ag1+ is bonded in a linear geometry to two equivalent N2+ atoms. Both Ag–N bond lengths are 2.01 Å. N2+ is bonded in a linear geometry to one Co3+ and one Ag1+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on CN2 by Materials Project

CN2 crystallizes in the tetragonal I-42d space group. The structure is three-dimensional. C4+ is bonded to four equivalent N2- atoms to form corner-sharing CN4 tetrahedra. All C–N bond lengths are 1.48 Å. N2- is bonded in a distorted trigonal planar geometry to two equivalent C4+ and one N2- atom. The N–N bond length is 1.36 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2024

Dual-pump Coherent anti-Stokes Raman scattering measurements in H 2 /CH 4 Counterflow Flames

Temperature and major species concentration measurements are reported in a Williams Seshadri counterflow burner using dual-pump coherent anti-Stokes Raman scattering (DPCARS). Hencken burner H2/Air flames with equivalence ratio of 0.8-1.4 were used to characterize the accuracy of the system. The mean errors for temperature, XH2/XN2 mole fraction ratio, and XO2/XN2 mole fraction ratio are 1.0%, 14.7%, and 5.5%, respectively. The counterflow burner uses a CH4, H2, and N2 mixture as fuel and synthetic air as oxidizer. Measurements were performed along the counterflow burner central axis for two different fuel compositions: 4% H2/86% CH4/10% N2 and 87%H2/3% CH4/10% N2. The measured temperature and species mole fractions agree well with the 1-D opposed-flow diffusion flame simulation. One observation is that the fuel inlet temperature is higher than 300 K, which suggests the possibility of the stagnation plane residing closer to the fuel side. Lastly, these measurements provide valuable data for testing and validation of advanced 2-D flame models.

Murdock, Benjamin K.↗
DOE OSTI2020

Membranes for fluid separation

Membranes, methods of making the membranes, and methods of using the membranes are described herein. The membranes can comprise a gas permeable support and a continuous phase comprising a selective inorganic material disposed within the gas permeable support. In some embodiments, the membranes can exhibit a CO2:N2 selectivity of at least 10 at 24° C. The membranes can be bendable, such that when the membranes are wrapped around a 1.5-inch diameter cylinder and returned to a planar conformation, the CO2:N2 selectivity of the membranes is at least 25% of the CO2:N2 selectivity of the membranes prior to having been wrapped around the cylinder.

36 MATERIALS SCIENCE↗
DOE OSTI2024

Transition from an incommensurate spin density wave to a commensurate magnetic order in a triangular lattice compound Ho 2 PdAl 6 Ge 4

Rare-earth (RE) intermetallics on a triangular lattice are promising candidates for generating interesting magnetic phases due to the complex interplay between Ruderman-Kittel-Kasuya-Yoshida (RKKY) interaction and geometrical frustration. Here, in this work, we report the exotic magnetic structure of a layered compound Ho 2 PdAl 6 Ge 4 with triangular lanthanide nets. Magnetization and heat capacity measurements in zero magnetic field reveal two magnetic phase transitions at T N1 = 10.8 K and T N2 = 6.0 K. Neutron powder diffraction demonstrates a commensurate antiferromagnetic phase with k 1 = (0, 0, 1.5) below T N2 . With increasing temperature, another incommensurate vector appears and therefore, the magnetic structure of the intermediate state is identified as an unusual incommensurate spin density wave with two propagation vectors k 1 = (0, 0, 1.5) and k 2 = (0.0492, 0.0492, 1.5). The magnetic moments in the intermediate state rotate continuously and form an unusual S-shaped wave arrangement in the ab plane, sharing similarities with typical cycloid and helix magnetic orders. These results identify Ho 2 PdAl 6 Ge 4 as a candidate for exploring field-induced topological magnetic phases such as skyrmions, opening the way for further investigations on the family of RE 2 PdAl 6 Ge 4 materials.

36 MATERIALS SCIENCE↗
DOE OSTI2024

Effect of post-deposition heat treatment on microstructure and mechanical properties of NASA HR-1 cold spray coatings

The primary goal of this work was to examine the impact of heat treatment on the evolution of microstructure and mechanical properties of NASA HR-1 cold spray coatings. Coatings were produced employing a high pressure cold spray system using N2 and He process gases and the effect of process gas and deposition temperature on the microstructure and mechanical properties of the coatings was examined. Microstructural characterization was performed using optical microscopy, scanning electron microscopy, micro X-ray computed tomography, and electron backscatter diffraction. NASA HR-1 coatings produced with He process gas exhibited improved plastic deformation and resulted in the lowest porosity compared to those deposited with N2 process gas. All coatings showed brittle failure with limited ductility in the as-deposited condition. Heat treatment of the NASA HR-1 cold spray coatings was performed at 550°C and 950°C for 1 h to improve the mechanical strength of the coatings. Heat treatment improved the particle bonding and enhanced the mechanical properties of the cold spray coatings. Heat treatment performed at 550°C resulted in higher mechanical strength of coatings, whereas the heat treatment performed at 950°C resulted in recrystallized microstructure and improved ductility of the coatings. However, heat treatment at 950°C resulted in forming the Eta (η) phase and Ni-Ti intermetallics in all the NASA HR-1 cold spray coatings. Here, the overall results suggest that using He as process gas contributed to reduced porosity and enhanced mechanical properties of the cold spray coatings.

21 SPECIFIC NUCLEAR REACTORS AND ASSOCIATED PLANTS↗
DOE OSTI2020

Machine Learning Analysis of Direct Dynamics Trajectory Outcomes for Thermal Deazetization of 2,3-Diazabicyclo[2.2.1]hept-2-ene

Experimentally, the thermal gas-phase deazetization of 2,3-diazabicyclo[2.2.1]hept-2-ene (1) results in the loss of N2 and the formation of bicyclo products 3 (exo) and 4 (endo) in a nonstatistical ratio, with preference for the exo product. Here, we report unrestricted M06-2X quasiclassical trajectories initialized from the concerted N2 ejection transition state that were able to replicate the experimental preference to form 3. We found that the 3:4 ratio results from the relative amounts of very fast (ballistic) exotype trajectories versus trajectories that lead to the 1,3-diradical intermediate 2. These quasiclassical trajectories provided a set of transition-state vibrational, velocity, momenta, and geometric features for the machine learning analysis. Additionally, a selection of popular supervised classification algorithms (e.g., random forest) provided poor prediction of trajectory outcomes based on only transition-state vibrational quanta and energy features. However, these machine learning models provided more accurate predictions using atomic velocities and atomic positions, attaining ~70% accuracy using initial conditions and between 85 and 95% accuracy at later reaction time steps. This increased accuracy allowed the feature importance analysis to reveal that, at the later-time analysis, the methylene bridge out-of-plane bending is correlated with trajectory outcomes for the formation of either the exo product or toward the diradical intermediate. Possible reasons for the struggle of machine learning algorithms to classify trajectories based on transition-state features is the heavily overlapping feature values, the finite but very large possible vibrational mode combinations, and the possibility of chaos as trajectories propagate. We examined this chaos by comparing a set of nearly identical trajectories that differed by only a very small scaling of the kinetic energies resulting from the transition-state reaction coordinate.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2022

Evaluation of a Third Generation Single-Component Water-Lean Diamine Solvent for Post-Combustion CO 2 Capture

Here this study describes a comprehensive evaluation of a recently developed water-lean diamine solvent, N1-(2-ethoxyethyl)-N2, N2-diisopropylethane-1,2-diamine (2-EEDIPEDA), to probe its potential post-combustion CO 2 capture performance. This evaluation includes (1) fundamental sorption characterization such as vapor-liquid equilibria, sorption kinetics and viscosity impacts; (2) continuous capture characterization using laboratory scale flow system using flue gas simulant; as well as (3) technoeconomic analysis of the capture process at industrial scale with projections for critical capture performance metrics. Using this evaluation, we compare the performance of 2-EEDIPEDA to our current leading water-lean amine-based solvent, 2-EEMPA, using the same baseline process plant configuration/pricing. From this comparison, we observe lower total cost of capture as low as $46.8/tonne CO 2 with 2-EEDIPEDA (20% cheaper than CANSOLV), as a direct result of solvent chemistry tuning leading to notable cost savings.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2024

Mechanistically Guided Materials Chemistry: Synthesis of Ternary Nitrides, CaZrN 2 and CaHfN 2

Recent computational studies have predicted many new ternary nitrides, revealing synthetic opportunities in this underexplored phase space. However, synthesizing new ternary nitrides is difficult, in part because intermediate and product phases often have high cohesive energies that inhibit diffusion. Here, we report the synthesis of two new phases, calcium zirconium nitride (CaZrN 2 ) and calcium hafnium nitride (CaHfN 2 ), by solid state metathesis reactions between Ca 3 N2 and MCl 4 (M = Zr, Hf). Although the reaction nominally proceeds to the target phases in a 1:1 ratio of the precursors via Ca 3 N 2 + MCl4 → CaMN 2 + 2 CaCl 2 , reactions prepared this way result in Ca-poor materials (Ca x M 2–x N2, x < 1). A small excess of Ca 3 N 2 (ca. 20 mol %) is needed to yield stoichiometric CaMN 2 , as confirmed by high-resolution synchrotron powder X-ray diffraction. In situ synchrotron X-ray diffraction studies reveal that nominally stoichiometric reactions produce Zr 3+ intermediates early in the reaction pathway, and the excess Ca 3 N 2 is needed to reoxidize Zr 3+ intermediates back to the Zr 4+ oxidation state of CaZrN 2 . Analysis of computationally derived chemical potential diagrams rationalizes this synthetic approach and its contrast from the synthesis of MgZrN 2 . These findings additionally highlight the utility of in situ diffraction studies and computational thermochemistry to provide mechanistic guidance for synthesis.

36 MATERIALS SCIENCE↗
DOE OSTI2022

Spectrally filtered ps–ns emission dynamics of atmospheric-pressure nanosecond pulsed plasmas

The temporal dynamics of atmospheric-pressure nanosecond pulsed plasma discharges in a pin-to-pin electrode configuration are studied using streak-camera line imaging of the interelectrode gap with a time resolution as short as ~25 ps. Discharge emission initiates homogeneously throughout the interelectrode gap with no detectable streamer propagation and then temporally decays in two distinct phases. Plasma emission bands attributed to various electronic transitions are tracked for single discharges in air and N 2 . Spectral filtering of the excited molecular states reveals that the N 2 (C–B) and N 2 (B–A) emission bands evolve in distinct early and late phases, respectively, with a time separation of ~15–20 ns. Furthermore, significant differences in the temporal dynamics of plasma discharges in air and N2 are observed. High levels of excited-state atomic oxygen and NO appear after the initial decay of the N 2 (C) state and coincide primarily with the latter phases of plasma evolution in air environments. From temporal traces of discharge emission, the formation and relaxation timescales of the electronically excited states of N 2 are quantified in pure N2 and air environments with sub-nanosecond resolution. The streak-OES (optical emission spectroscopy) technique enables quantitative time-resolved studies of key chemical species for model validation in ultra-short-pulsed plasmas.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2022

Numerical study of pure rotational fs/ps CARS coherence beating at high pressure and for multi-species rotation-vibration non-equilibrium thermometry

Coherent anti-Stokes Raman scattering (CARS) has long been the gold standard for non-intrusively measuring gas temperature in reacting flows such as flames and plasmas. Recently, the development of ultrafast hybrid fs/ps CARS has enabled the exploitation of coherence beating between neighboring spectral lines to simultaneously measure rotational and vibrational temperatures from a single pure rotational spectrum. However, the influence of non-Boltzmann vibrational state distributions and limitations due to collisional dephasing at pressures greater than 1 atm remains unclear. In this work, we use spectral simulations to investigate the effects of non-Boltzmann vibrational state distributions and the applicability of coherence beating at pressures up to 10 atm. We show that short probe pulses can be leveraged to quantify non-Boltzmann vibrational state distributions of N2. Furthermore, we demonstrate that fs/ps CARS coherence beating can simultaneously provide sensitive measurements of rotational and vibrational temperatures of both O2 and N2 in air. A sensitivity analysis was conducted to qualitatively explain the accuracy and precision comparisons between probe delays.

Chen, Timothy Y. (ORCID:0000000330269767)↗
DOE OSTI2024

Improving gas adsorption modeling for MOFs by local calibration of Hubbard U parameters

While computational screening with density functional theory (DFT) is frequently employed for the screening of metal–organic frameworks (MOFs) for gas separation and storage, commonly applied generalized gradient approximations (GGAs) exhibit self-interaction errors, which hinder the predictions of adsorption energies. We investigate the Hubbard U parameter to augment DFT calculations for full periodic MOFs, targeting a more precise modeling of gas molecule–MOF interactions, specifically for N2, CO2, and O2. We introduce a calibration scheme for the U parameter, which is tailored for each MOF, by leveraging higher-level calculations on the secondary building unit (SBU) of the MOF. When applied to the full periodic MOF, the U parameter calibrated against hybrid HSE06 calculations of SBUs successfully reproduces hybrid-quality calculations of the adsorption energy of the periodic MOF. The mean absolute deviation of adsorption energies reduces from 0.13 eV for a standard GGA treatment to 0.06 eV with the calibrated U, demonstrating the utility of the calibration procedure when applied to the full MOF structure. Furthermore, attempting to use coupled cluster singles and doubles with perturbative triples calculations of isolated SBUs for this calibration procedure shows varying degrees of success in predicting the experimental heat of adsorption. It improves accuracy for N2 adsorption for cases of overbinding, whereas its impact on CO2 is minimal, and ambiguities in spin state assignment hinder consistent improvements of O2 adsorption. Our findings emphasize the limitations of cluster models and advocate the use of full periodic MOF systems with a calibrated U parameter, providing a more comprehensive understanding of gas adsorption in MOFs.

Chemistry↗