Search NASA⌕ Search

SEARCH · Search NASA

Results for “direct bonding”

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 235 records · Page 13
All sourcesNASA NTRSDOE OSTI
DOE OSTI2025

Atmospheric-pressure ammonia synthesis on AuRu catalysts enabled by plasmon-controlled hydrogenation and nitrogen-species desorption

The Haber–Bosch process for ammonia synthesis contributes up to ~3% of global greenhouse gas emissions. Plasmonic catalysts strongly concentrate light and can alter the reaction intermediates via out-of-equilibrium processes, providing the potential for an alternative, less-energy-intensive pathway to synthesize ammonia. Here, in this study, we show that gold-ruthenium (AuRu) bimetallic nanoparticles can synthesize ammonia at room temperature and pressure using visible light. We create AuRu alloys with varying compositions and achieve ammonia production rates of ~60 μmol per gram of catalyst bed per hour. In situ infrared spectroscopy reveals that light accelerates the hydrogenation of nitrogen intermediates compared to conventional thermal catalysis. Through computational modelling, we demonstrate that photo-excited electrons enable associative hydrogenation pathways for nitrogen activation rather than direct nitrogen–nitrogen bond breaking. This light-assisted mechanism requires both hydrogen and light working together to overcome the nitrogen activation barrier, mimicking how biological enzymes produce ammonia naturally and providing fundamental insights for developing sustainable, energy-efficient chemical synthesis.

Yuan, Lin [Stanford Univ., CA (United States)] (OR↗
DOE OSTI2022

Probing charge density in materials with atomic resolution in real space

The charge distribution in materials at the nanoscale can often explain the origin of macroscopic properties such as localized conductivity or the plasmonic response and illuminate more fundamental changes in the microscopic structure such as changes in chemical bonding characteristics. Previously, direct visualization of the charge density with high spatial resolution was often a missing link in the formation of structure–property relationships, especially in heterogeneous materials systems. Furthermore, recent advancements in microscopy technology have enabled researchers to visualize the charge distribution in materials down to subatomic length scales. In this Technical Review, we discuss the developments in high-resolution real-space charge distribution imaging using diffraction techniques and electron microscopy, with a focus on the recent advancement of four-dimensional scanning transmission electron microscopy, electron holography, and applications to materials interfaces.

Electronic properties and materials↗
DOE OSTI2020

Subpicosecond HI elimination in the 266 nm photodissociation of branched iodoalkanes

Here, the 266 nm photodissociation dynamics of 1-iodopropane and 2-iodopropane were studied using photofragment translational energy spectroscopy using vacuum ultraviolet (VUV) photoionization and electron impact ionization detection of products. The photochemistry of 1-iodopropane was found to be similar to that of iodomethane and iodoethane, with dominant production of I*( 2 P 1/2 ), and no evidence (<0.21%) for HI + alkene formation. Significantly different behavior was observed for 2-iodopropane, with dominant production of ground state I( 2 P 3/2 ), and a HI yield >10.5%. The anisotropy (β) parameters for all channels approached the limiting value of 2.0, indicating that 1,2-HI elimination occurs on subpicosecond timescales, like direct C–I bond fission, following excitation to 3 Q 0 . The HI translational energy and angular distributions were similar to those for I( 2 P 3/2 ), suggesting that motion of the heavy I atom in HI is largely derived from the repulsive nature of the 1 Q 1 surface correlating to R + I with the light H atom picked up by ground state I late in the exit channel producing highly vibrationally excited HI.

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

Hydrogen ejection from hydrocarbons: Characterization and relevance in soot formation and interstellar chemistry

Polycyclic aromatic hydrocarbons (PAHs) play a major role in the chemistry of combustion, pyrolysis, and the interstellar medium. Production (or activation) of radical PAHs and propagation of their resulting reactions require efficient dehydrogenation, but the preferred method of hydrogen loss is not well understood. Unimolecular hydrogen ejection (i.e., direct C─H bond fission) and bimolecular radical abstraction are two main candidate pathways. We performed a computational study to characterize the role of H ejection, particularly as a driver for radical-centric hydrocarbon-growth mechanisms and particle formation. Electronic structure calculations establish that C─H bond strengths span a broad range of energies, which can be weaker than 30 kcal/mol in some C 9 and C 13 PAH radicals. At T > 1200 K, calculated thermal rates for hydrogen ejection from weak C─H bonds at zigzag sites on PAH radicals are significantly larger than typical H-abstraction rates. These results are highly relevant in the context of chain reactions of radical species and soot inception under fuel-rich combustion conditions. Furthermore, calculated microcanonical rates that include the additional internal energy released by bond formation (e.g., ring closure to yield C 9 H 9 ) yield significantly higher rates than those associated with full thermalization. These microcanonical considerations are relevant to the astrochemical processes associated with hydrocarbon growth and processing in the low-density interstellar environment.

08 HYDROGEN↗
DOE OSTI2021

Single-crystalline epitaxial TiO film: A metal and superconductor, similar to Ti metal

Titanium monoxide (TiO), an important member of the rock salt 3d transition-metal monoxides, has not been studied in the stoichiometric single-crystal form. It has been challenging to prepare stoichiometric TiO due to the highly reactive Ti 2+ . We adapt a closely lattice-matched MgO(001) substrate and report the successful growth of single-crystalline TiO(001) film using molecular beam epitaxy. This enables a first-time study of stoichiometric TiO thin films, showing that TiO is metal but in proximity to Mott insulating state. We observe a transition to the superconducting phase below 0.5 K close to that of Ti metal. Density functional theory (DFT) and a DFT-based tight-binding model demonstrate the extreme importance of direct Ti–Ti bonding in TiO, suggesting that similar superconductivity exists in TiO and Ti metal. Our work introduces the new concept that TiO behaves more similar to its metal counterpart, distinguishing it from other 3d transition-metal monoxides.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2020

Materials Data on CuH3C2NO4 by Materials Project

CuC2NH3O4 crystallizes in the orthorhombic Pbca space group. The structure is two-dimensional and consists of two CuC2NH3O4 sheets oriented in the (0, 0, 1) direction. Cu2+ is bonded to one N3- and five O2- atoms to form distorted corner-sharing CuNO5 octahedra. The corner-sharing octahedral tilt angles are 57°. The Cu–N bond length is 1.99 Å. There are a spread of Cu–O bond distances ranging from 2.00–2.58 Å. There are two inequivalent C3+ sites. In the first C3+ site, C3+ is bonded in a bent 120 degrees geometry to two O2- atoms. Both C–O bond lengths are 1.27 Å. In the second C3+ site, C3+ is bonded in a bent 120 degrees geometry to two O2- atoms. There is one shorter (1.26 Å) and one longer (1.28 Å) C–O bond length. N3- is bonded in a distorted trigonal non-coplanar geometry to one Cu2+ and three H1+ atoms. There is two shorter (1.02 Å) and one longer (1.03 Å) N–H bond length. There are three inequivalent H1+ sites. In the first H1+ site, H1+ is bonded in a single-bond geometry to one N3- atom. In the second H1+ site, H1+ is bonded in a single-bond geometry to one N3- atom. In the third H1+ site, H1+ is bonded in a single-bond geometry to one N3- atom. There are four inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted single-bond geometry to two equivalent Cu2+ and one C3+ atom. In the second O2- site, O2- is bonded in a distorted water-like geometry to one Cu2+ and one C3+ atom. In the third O2- site, O2- is bonded in a distorted water-like geometry to one Cu2+ and one C3+ atom. In the fourth O2- site, O2- is bonded in a bent 120 degrees geometry to one Cu2+ and one C3+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on CuH8C4(NO3)2 by Materials Project

CuC4H8(NO3)2 crystallizes in the monoclinic P2_1/c space group. The structure is two-dimensional and consists of one CuC4H8(NO3)2 sheet oriented in the (0, 0, 1) direction. Cu2+ is bonded in a distorted octahedral geometry to six O2- atoms. There are a spread of Cu–O bond distances ranging from 1.95–2.58 Å. There are two inequivalent C2+ sites. In the first C2+ site, C2+ is bonded in a trigonal planar geometry to one N3-, one H1+, and one O2- atom. The C–N bond length is 1.33 Å. The C–H bond length is 1.11 Å. The C–O bond length is 1.25 Å. In the second C2+ site, C2+ is bonded in a trigonal planar geometry to one H1+ and two O2- atoms. The C–H bond length is 1.11 Å. Both C–O bond lengths are 1.27 Å. N3- is bonded in a trigonal planar geometry to one C2+ and two H1+ atoms. There is one shorter (1.02 Å) and one longer (1.03 Å) N–H bond length. There are four inequivalent H1+ sites. In the first H1+ site, H1+ is bonded in a single-bond geometry to one N3- atom. In the second H1+ site, H1+ is bonded in a single-bond geometry to one N3- atom. In the third H1+ site, H1+ is bonded in a single-bond geometry to one C2+ atom. In the fourth H1+ site, H1+ is bonded in a single-bond geometry to one C2+ atom. There are three inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted single-bond geometry to one Cu2+ and one C2+ atom. In the second O2- site, O2- is bonded in a bent 120 degrees geometry to one Cu2+ and one C2+ atom. In the third O2- site, O2- is bonded in a bent 120 degrees geometry to one Cu2+ and one C2+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on K2CuH8(CO3)4 by Materials Project

K2CuH8(CO3)4 crystallizes in the monoclinic P2_1/c space group. The structure is two-dimensional and consists of two K2CuH8(CO3)4 sheets oriented in the (0, 1, 0) direction. K1+ is bonded in a 7-coordinate geometry to seven O2- atoms. There are a spread of K–O bond distances ranging from 2.81–2.95 Å. Cu2+ is bonded in a square co-planar geometry to four O2- atoms. There is two shorter (1.97 Å) and two longer (1.98 Å) Cu–O bond length. There are two inequivalent C3+ sites. In the first C3+ site, C3+ is bonded in a bent 120 degrees geometry to two O2- atoms. There is one shorter (1.25 Å) and one longer (1.30 Å) C–O bond length. In the second C3+ site, C3+ is bonded in a bent 120 degrees geometry to two O2- atoms. There is one shorter (1.24 Å) and one longer (1.30 Å) C–O bond length. There are four 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 0.99 Å. In the second 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 third H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.99 Å. 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. There are six inequivalent O2- sites. In the first O2- site, O2- is bonded in a bent 120 degrees geometry to one Cu2+ and one C3+ atom. In the second O2- site, O2- is bonded in a distorted single-bond geometry to three equivalent K1+ and one C3+ atom. In the third O2- site, O2- is bonded in a water-like geometry to one K1+ and two H1+ atoms. In the fourth O2- site, O2- is bonded in a water-like geometry to two equivalent K1+ and two H1+ atoms. In the fifth O2- site, O2- is bonded in a bent 120 degrees geometry to one Cu2+ and one C3+ atom. In the sixth O2- site, O2- is bonded in a distorted single-bond geometry to one K1+ and one C3+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on LiBH15C5NO3 by Materials Project

LiBC5NH15O3 crystallizes in the monoclinic P2_1/c space group. The structure is two-dimensional and consists of one LiBC5NH15O3 sheet oriented in the (0, 0, 1) direction. Li1+ is bonded to one N3-, two H1+, and two O2- atoms to form distorted LiH2NO2 trigonal bipyramids that share a cornercorner with one BH3N tetrahedra, corners with six CH2O2 tetrahedra, and an edgeedge with one BH3N tetrahedra. The Li–N bond length is 2.09 Å. There are one shorter (1.95 Å) and one longer (2.07 Å) Li–H bond lengths. There are one shorter (2.09 Å) and one longer (2.15 Å) Li–O bond lengths. B3+ is bonded to one N3- and three H1+ atoms to form BH3N tetrahedra that share corners with two CH3N tetrahedra, a cornercorner with one LiH2NO2 trigonal bipyramid, and an edgeedge with one LiH2NO2 trigonal bipyramid. The B–N bond length is 1.55 Å. There are a spread of B–H bond distances ranging from 1.23–1.26 Å. There are five inequivalent C2- sites. In the first C2- site, C2- is bonded to two H1+ and two O2- atoms to form CH2O2 tetrahedra that share corners with two CH2O2 tetrahedra and a cornercorner with one LiH2NO2 trigonal bipyramid. There is one shorter (1.09 Å) and one longer (1.11 Å) C–H bond length. There is one shorter (1.42 Å) and one longer (1.43 Å) C–O bond length. In the second C2- site, C2- is bonded to two H1+ and two O2- atoms to form CH2O2 tetrahedra that share corners with two CH2O2 tetrahedra and corners with two equivalent LiH2NO2 trigonal bipyramids. There is one shorter (1.09 Å) and one longer (1.10 Å) C–H bond length. Both C–O bond lengths are 1.43 Å. In the third C2- site, C2- is bonded to one N3- and three H1+ atoms to form CH3N tetrahedra that share a cornercorner with one BH3N tetrahedra, a cornercorner with one CH3N tetrahedra, and a cornercorner with one LiH2NO2 trigonal bipyramid. The C–N bond length is 1.46 Å. There is two shorter (1.10 Å) and one longer (1.11 Å) C–H bond length. In the fourth C2- site, C2- is bonded to one N3- and three H1+ atoms to form CH3N tetrahedra that share a cornercorner with one BH3N tetrahedra, a cornercorner with one CH3N tetrahedra, and a cornercorner with one LiH2NO2 trigonal bipyramid. The C–N bond length is 1.46 Å. There is two shorter (1.10 Å) and one longer (1.11 Å) C–H bond length. In the fifth C2- site, C2- is bonded to two H1+ and two O2- atoms to form CH2O2 tetrahedra that share corners with two CH2O2 tetrahedra and a cornercorner with one LiH2NO2 trigonal bipyramid. There is one shorter (1.09 Å) and one longer (1.11 Å) C–H bond length. There is one shorter (1.42 Å) and one longer (1.43 Å) C–O bond length. N3- is bonded in a tetrahedral geometry to one Li1+, one B3+, and two C2- atoms. There are fifteen inequivalent H1+ sites. In the first H1+ site, H1+ is bonded in a single-bond geometry to one C2- atom. In the second H1+ site, H1+ is bonded in an L-shaped geometry to one Li1+ and one B3+ atom. In the third H1+ site, H1+ is bonded in a single-bond geometry to one C2- atom. In the fourth H1+ site, H1+ is bonded in a single-bond geometry to one C2- atom. In the fifth H1+ site, H1+ is bonded in a single-bond geometry to one B3+ atom. In the sixth H1+ site, H1+ is bonded in a single-bond geometry to one C2- atom. In the seventh H1+ site, H1+ is bonded in a single-bond geometry to one C2- atom. In the eighth H1+ site, H1+ is bonded in a single-bond geometry to one C2- atom. In the ninth H1+ site, H1+ is bonded in a single-bond geometry to one C2- atom. In the tenth H1+ site, H1+ is bonded in a single-bond geometry to one C2- atom. In the eleventh H1+ site, H1+ is bonded in a single-bond geometry to one C2- atom. In the twelfth H1+ site, H1+ is bonded in a single-bond geometry to one C2- atom. In the thirteenth H1+ site, H1+ is bonded in a single-bond geometry to one C2- atom. In the fourteenth H1+ site, H1+ is bonded in a single-bond geometry to one C2- atom. In the fifteenth H1+ site, H1+ is bonded in an L-shaped geometry to one Li1+ and one B3+ atom. There are three inequivalent O2- sites. In the first O2- site, O2- is bonded in a trigonal planar geometry to one Li1+ and two C2- atoms. In the second O2- site, O2- is bonded in a water-like geometry to two C2- atoms. In the third O2- site, O2- is bonded in a trigonal planar geometry to one Li1+ and two C2- atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Hf2S by Materials Project

Hf2S is Molybdenite-like structured and crystallizes in the hexagonal P6_3/mmc space group. The structure is two-dimensional and consists of two Hf2S sheets oriented in the (0, 0, 1) direction. Hf is bonded in a 3-coordinate geometry to three equivalent S atoms. All Hf–S bond lengths are 2.63 Å. S is bonded to six equivalent Hf atoms to form distorted edge-sharing SHf6 pentagonal pyramids.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on GaTe by Materials Project

GaTe is black P-derived structured and crystallizes in the hexagonal P6_3/mmc space group. The structure is two-dimensional and consists of four GaTe sheets oriented in the (0, 0, 1) direction. Ga2+ is bonded in a distorted trigonal non-coplanar geometry to three equivalent Te2- atoms. All Ga–Te bond lengths are 2.71 Å. Te2- is bonded in a distorted trigonal non-coplanar geometry to three equivalent Ga2+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on TaS2 by Materials Project

TaS2 is Molybdenite-like structured and crystallizes in the trigonal R3m space group. The structure is two-dimensional and consists of three TaS2 sheets oriented in the (0, 0, 1) direction. Ta4+ is bonded to six equivalent S2- atoms to form distorted edge-sharing TaS6 pentagonal pyramids. All Ta–S bond lengths are 2.48 Å. S2- is bonded in a 3-coordinate geometry to three equivalent Ta4+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on NbS2 by Materials Project

NbS2 is Molybdenite-like structured and crystallizes in the hexagonal P6_3/mmc space group. The structure is two-dimensional and consists of two NbS2 sheets oriented in the (0, 0, 1) direction. Nb4+ is bonded to six equivalent S2- atoms to form distorted edge-sharing NbS6 pentagonal pyramids. All Nb–S bond lengths are 2.49 Å. S2- is bonded in a 3-coordinate geometry to three equivalent Nb4+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Ta2N by Materials Project

Ta2N is trigonal omega structured and crystallizes in the trigonal P-3m1 space group. The structure is two-dimensional and consists of one Ta2N sheet oriented in the (0, 0, 1) direction. Ta is bonded in a distorted T-shaped geometry to three equivalent N atoms. All Ta–N bond lengths are 2.18 Å. N is bonded to six equivalent Ta atoms to form edge-sharing NTa6 octahedra.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on NbSe2 by Materials Project

NbSe2 is trigonal omega structured and crystallizes in the trigonal P-3m1 space group. The structure is two-dimensional and consists of one NbSe2 sheet oriented in the (0, 0, 1) direction. Nb4+ is bonded to six equivalent Se2- atoms to form edge-sharing NbSe6 octahedra. All Nb–Se bond lengths are 2.62 Å. Se2- is bonded in a 3-coordinate geometry to three equivalent Nb4+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on NiTe by Materials Project

NiTe is lead oxide-like structured and crystallizes in the trigonal R-3m space group. The structure is two-dimensional and consists of three NiTe sheets oriented in the (0, 0, 1) direction. Ni2+ is bonded to four equivalent Te2- atoms to form a mixture of edge and corner-sharing NiTe4 tetrahedra. There are three shorter (2.50 Å) and one longer (2.54 Å) Ni–Te bond lengths. Te2- is bonded in a 4-coordinate geometry to four equivalent Ni2+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Zn(ReO4)2 by Materials Project

Zn(ReO4)2 crystallizes in the trigonal P-3 space group. The structure is two-dimensional and consists of one Zn(ReO4)2 sheet oriented in the (0, 0, 1) direction. Re7+ is bonded to four O2- atoms to form ReO4 tetrahedra that share corners with three equivalent ZnO6 octahedra. The corner-sharing octahedral tilt angles are 17°. There is one shorter (1.73 Å) and three longer (1.76 Å) Re–O bond length. Zn2+ is bonded to six equivalent O2- atoms to form ZnO6 octahedra that share corners with six equivalent ReO4 tetrahedra. All Zn–O bond lengths are 2.09 Å. There are two inequivalent O2- sites. In the first O2- site, O2- is bonded in a single-bond geometry to one Re7+ atom. In the second O2- site, O2- is bonded in a distorted linear geometry to one Re7+ and one Zn2+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Mn(SbS2)2 by Materials Project

MnSb2S4 crystallizes in the monoclinic C2/m space group. The structure is two-dimensional and consists of two MnSb2S4 sheets oriented in the (0, 0, 1) direction. Mn2+ is bonded to six S2- atoms to form MnS6 octahedra that share corners with four equivalent SbS5 square pyramids, edges with two equivalent MnS6 octahedra, and edges with six equivalent SbS5 square pyramids. There are two shorter (2.56 Å) and four longer (2.61 Å) Mn–S bond lengths. Sb3+ is bonded to five S2- atoms to form distorted SbS5 square pyramids that share corners with two equivalent MnS6 octahedra, edges with three equivalent MnS6 octahedra, and edges with four equivalent SbS5 square pyramids. The corner-sharing octahedral tilt angles are 12°. There are a spread of Sb–S bond distances ranging from 2.51–3.04 Å. There are two inequivalent S2- sites. In the first S2- site, S2- is bonded in a 3-coordinate geometry to one Mn2+ and two equivalent Sb3+ atoms. In the second S2- site, S2- is bonded to two equivalent Mn2+ and three equivalent Sb3+ atoms to form a mixture of distorted edge and corner-sharing SMn2Sb3 square pyramids.

36 MATERIALS SCIENCE↗