Search NASA⌕ Search

SEARCH · Search NASA

Results for “BROMINE”

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 127 records · Page 7
All sourcesNASA NTRSDOE OSTI
DOE OSTI2020

Covalent surface modifications and superconductivity of two-dimensional metal carbide MXenes

Versatile chemical transformations of surface functional groups in two-dimensional transition-metal carbides (MXenes) open up a previously unexplored design space for this broad class of functional materials. We introduce a general strategy to install and remove surface groups by performing substitution and elimination reactions in molten inorganic salts. Successful synthesis of MXenes with oxygen, imido, sulfur, chlorine, selenium, bromine, and tellurium surface terminations, as well as bare MXenes (no surface termination), was demonstrated. These MXenes show distinctive structural and electronic properties. For example, the surface groups control interatomic distances in the MXene lattice, and Ti n +1 C n ( n = 1, 2) MXenes terminated with telluride (Te 2− ) ligands show a giant (>18%) in-plane lattice expansion compared with the unstrained titanium carbide lattice. The surface groups also control superconductivity of niobium carbide MXenes.

Kamysbayev, Vladislav↗
DOE OSTI2020

Rational synthesis of atomically precise graphene nanoribbons directly on metal oxide surfaces

Atomically precise graphene nanoribbons (GNRs) attract great interest because of their highly tunable electronic, optical, and transport properties. However, on-surface synthesis of GNRs is typically based on metal surface–assisted chemical reactions, where metallic substrates strongly screen their designer electronic properties and limit further applications. In this work, we present an on-surface synthesis approach to forming atomically precise GNRs directly on semiconducting metal oxide surfaces. The thermally triggered multistep transformations preprogrammed in our precursors’ design rely on highly selective and sequential activations of carbon-bromine (C-Br) and carbon-fluorine (C-F) bonds and cyclodehydrogenation. The formation of planar armchair GNRs terminated by well-defined zigzag ends is confirmed by scanning tunneling microscopy and spectroscopy, which also reveal weak interaction between GNRs and the rutile titanium dioxide substrate.

36 MATERIALS SCIENCE↗
DOE OSTI2022

Compositional texture engineering for highly stable wide-bandgap perovskite solar cells

The development of highly stable and efficient wide-bandgap (WBG) perovskite solar cells (PSCs) based on bromine-iodine (Br–I) mixed-halide perovskite (with Br greater than 20%) is critical to create tandem solar cells. However, issues with Br–I phase segregation under solar cell operational conditions (such as light and heat) limit the device voltage and operational stability. This challenge is often exacerbated by the ready defect formation associated with the rapid crystallization of Br-rich perovskite chemistry with antisolvent processes. We combined the rapid Br crystallization with a gentle gas-quench method to prepare highly textured columnar 1.75–electron volt Br–I mixed WBG perovskite films with reduced defect density. Here, with this approach, we obtained 1.75–electron volt WBG PSCs with greater than 20% power conversion efficiency, approximately 1.33-volt open-circuit voltage (V oc ), and excellent operational stability (less than 5% degradation over 1100 hours of operation under 1.2 sun at 65°C). When further integrated with 1.25–electron volt narrow-bandgap PSC, we obtained a 27.1% efficient, all-perovskite, two-terminal tandem device with a high V oc of 2.2 volts.

14 SOLAR ENERGY↗
DOE OSTI2025

Substituent effect on napthodithiophene-fused porphyrins: Understanding the unusual trend of fluorescence quantum yield quenching

A series of π-extended porphyrins containing thiophene units was prepared to investigate an unusual trend observed in the fluorescence quantum yield of naphtho[2,1-b:3,4-b']dithiophene-fused porphyrins. Monobenzoporphyrins carrying 2-thiophenyl (vinyl thiophene porphyrin) groups (2VTP, 2VTBr and Br2VTP) (numbering 2 and 3 refers to the position of sulfur on the thiophene ring) were synthesized through a Heck-based cascade reaction followed by a newly developed bromination method. These were converted to naphtho[2,1-b:3,4-b']dithiophene-fused porphyrin derivatives (FBr2VTP and F2VTBr) via ring closure with an intramolecular Scholl reaction. Increasingly larger Stokes shifts with a higher number of bromo groups were observed in the unfused π-extended molecular systems, reflecting the heavy atom effect. Fluorescence spectroscopy further confirmed the unusual trend seen in the previous work: structural rigidification in naphtho[2,1-b:3,4-b']dithiophene-fused porphyrins leads to longer fluorescence lifetimes but unexpectedly lowers the quantum yield. Adding one bromo group to the naphtho[2,1-b:3,4-b']dithiophene unit does not change this trend. Furthermore, the presence of two bromo groups prevents the quantum yield from dropping. DFT, TDDFT, and NICS analyses suggest a drastic change in aromaticity in the pyrrole ring where the naphtho[2,1-b:3,4-b']dithiophene is fused in FBr2VTP, which might contribute to the quantum yield reductions.

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

Theoretical analysis of the role of complex transition dipole phase in XUV transient-absorption probing of charge migration

We theoretically investigate the role of complex dipole phase in the attosecond probing of charge migration. The iodobromoacetylene ion (ICCBr + ) is considered as an example, in which one can probe charge migration by accessing both the iodine and bromine ends of the molecule with different spectral windows of an extreme-ultraviolet (XUV) pulse. The analytical expression for transient absorption shows that the site-specific information of charge migration is encoded in the complex phase of cross dipole products for XUV transitions between the I-4 d and Br-3 d spectral windows. Ab-initio quantum chemistry calculations on ICCBr + reveal that there is a constant π phase difference between the I-4 d and Br-3 d transient-absorption spectral windows, irrespective of the fine-structure energy splittings. Transient absorption spectra are simulated with a multistate model including the complex dipole phase, and the results correctly reconstruct the charge-migration dynamics via the quantum beats in the two element spectral windows, exhibiting out-of-phase oscillations.

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

Process optimization of caustic scrubber and iodine-129 immobilization in sodalite-based waste forms

Caustic scrubbers are proposed to remove vaporized iodine from nuclear fuel reprocessing plants. Resulting caustic slurries of radioactive iodine ( 129 I) and other anions can be captured and immobilized into the cage structures of sodalite-type minerals. Here, mixed anion sodalites were hydrothermally synthesized from a simulated caustic scrubber solution containing hydroxide/water, carbonate, chlorine, bromine, iodine, nitrate, and nitrite ions with added kaolinite. Experiments were conducted with twenty-five different sets of process conditions. Resulting powders were characterized by quantitative X-ray diffraction (XRD) and multi-functional thermal analysis, including gravimetry, calorimetry, and mass spectrometry. Using statistical analysis, process variables were tailored to maximize conversion of kaolinite into cage silicates, immobilize caustic scrubber anions, and minimize amorphous content. Further, chemical analysis showed the incorporation of all the targeted ions into the solids. Detailed investigation of a batch characterized after washing (creating secondary waste) and one without washing but subsequent calcination is given. This work contributes to defining the constraints required for subsequent consolidation process steps of the waste form to avoid volatilization.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2020

Materials Data on Br by Materials Project

Br is Protactinium structured and crystallizes in the orthorhombic Cmce space group. The structure is zero-dimensional and consists of four bromine molecules. Br is bonded in a distorted single-bond geometry to one Br atom. The Br–Br bond length is 2.39 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on TeAuBr8 by Materials Project

AuTeBr7Br crystallizes in the triclinic P-1 space group. The structure is zero-dimensional and consists of one bromine molecule and one AuTeBr7 cluster. In the AuTeBr7 cluster, Au2+ is bonded in a rectangular see-saw-like geometry to four Br1- atoms. There are a spread of Au–Br bond distances ranging from 2.46–2.50 Å. Te6+ is bonded in a distorted octahedral geometry to six Br1- atoms. There are a spread of Te–Br bond distances ranging from 2.53–3.15 Å. There are seven inequivalent Br1- sites. In the first Br1- site, Br1- is bonded in a distorted L-shaped geometry to one Au2+ and one Te6+ atom. In the second Br1- site, Br1- is bonded in a distorted water-like geometry to one Au2+ and one Te6+ atom. In the third Br1- site, Br1- is bonded in a distorted L-shaped geometry to one Au2+ and one Te6+ atom. In the fourth Br1- site, Br1- is bonded in a single-bond geometry to one Au2+ atom. In the fifth Br1- site, Br1- is bonded in a single-bond geometry to one Te6+ atom. In the sixth Br1- site, Br1- is bonded in a single-bond geometry to one Te6+ atom. In the seventh Br1- site, Br1- is bonded in a single-bond geometry to one Te6+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on BrCl by Materials Project

BrCl is alpha carbon monoxide-like structured and crystallizes in the hexagonal P6_3mc space group. The structure is zero-dimensional and consists of two bromine chloride molecules. Br is bonded in a single-bond geometry to one Cl atom. The Br–Cl bond length is 2.17 Å. Cl is bonded in a single-bond geometry to one Br atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Br by Materials Project

Br is Cubic alpha N2-like structured and crystallizes in the orthorhombic Fddd space group. The structure is zero-dimensional and consists of sixty-four bromine molecules. Br is bonded in a single-bond geometry to one Br atom. The Br–Br bond length is 2.32 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on PBr2 by Materials Project

P(Br)2 is High Pressure Cadmuum Telluride structured and crystallizes in the tetragonal P4/mmm space group. The structure is zero-dimensional and consists of one bromine molecule and one phosphine molecule.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on YbMoBrO4 by Materials Project

Yb2Mo2O8BrBr crystallizes in the triclinic P-1 space group. The structure is three-dimensional and consists of one bromine molecule and one Yb2Mo2O8Br framework. In the Yb2Mo2O8Br framework, there are two inequivalent Yb3+ sites. In the first Yb3+ site, Yb3+ is bonded in a 5-coordinate geometry to five O2- and one Br1- atom. There are a spread of Yb–O bond distances ranging from 2.26–2.53 Å. The Yb–Br bond length is 2.96 Å. In the second Yb3+ site, Yb3+ is bonded in a 7-coordinate geometry to seven O2- atoms. There are a spread of Yb–O bond distances ranging from 2.28–2.74 Å. There are two inequivalent Mo6+ sites. In the first Mo6+ site, Mo6+ is bonded in a tetrahedral geometry to four O2- atoms. There are a spread of Mo–O bond distances ranging from 1.78–1.83 Å. In the second Mo6+ site, Mo6+ is bonded in a tetrahedral geometry to four O2- atoms. There are a spread of Mo–O bond distances ranging from 1.77–1.84 Å. There are eight inequivalent O2- sites. In the first O2- site, O2- is bonded in a 3-coordinate geometry to one Yb3+, one Mo6+, and one Br1- atom. The O–Br bond length is 2.61 Å. In the second O2- site, O2- is bonded in a linear geometry to one Yb3+ and one Mo6+ atom. In the third O2- site, O2- is bonded in a 3-coordinate geometry to two Yb3+ and one Mo6+ atom. In the fourth O2- site, O2- is bonded in a 3-coordinate geometry to two Yb3+ and one Mo6+ atom. In the fifth O2- site, O2- is bonded in a distorted linear geometry to one Yb3+ and one Mo6+ atom. In the sixth O2- site, O2- is bonded in a 2-coordinate geometry to two Yb3+ and one Mo6+ atom. In the seventh O2- site, O2- is bonded in a linear geometry to one Yb3+ and one Mo6+ atom. In the eighth O2- site, O2- is bonded in a 3-coordinate geometry to two Yb3+ and one Mo6+ atom. Br1- is bonded in a 2-coordinate geometry to one Yb3+ and one O2- atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on PdRuBr4N5Cl by Materials Project

PdRuN3Br2N2BrBrCl crystallizes in the orthorhombic Pnma space group. The structure is zero-dimensional and consists of four bromine chloride molecules, four hydrobromic acid molecules, four nitrogen gas molecules, four palladium on carbon molecules, and four RuN3Br2 clusters. In each RuN3Br2 cluster, Ru6+ is bonded in a trigonal non-coplanar geometry to three N3- atoms. There is one shorter (1.66 Å) and two longer (1.85 Å) Ru–N bond length. There are two inequivalent N3- sites. In the first N3- site, N3- is bonded in a distorted bent 120 degrees geometry to one Ru6+ and one Br2+ atom. The N–Br bond length is 1.86 Å. In the second N3- site, N3- is bonded in a single-bond geometry to one Ru6+ atom. Br2+ is bonded in a single-bond geometry to one N3- atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on C15BrCl6 by Materials Project

(C)9(CCl)6Br crystallizes in the triclinic P-1 space group. The structure is zero-dimensional and consists of two bromine molecules, twenty-four chloromethane molecules, six ethyne molecules, and twenty-four methane molecules.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on CoPtBr4N5Cl by Materials Project

CoPtN3Br2N2BrBrCl crystallizes in the orthorhombic Pnma space group. The structure is zero-dimensional and consists of four bromine chloride molecules, four hydrobromic acid molecules, four nitrogen molecules, and four CoPtN3Br2 clusters. In each CoPtN3Br2 cluster, Co2+ is bonded in a trigonal planar geometry to three N3- atoms. There is one shorter (1.63 Å) and two longer (1.72 Å) Co–N bond length. Pt6+ is bonded in a single-bond geometry to one N3- atom. The Pt–N bond length is 1.86 Å. There are two inequivalent N3- sites. In the first N3- site, N3- is bonded in a bent 150 degrees geometry to one Co2+ and one Pt6+ atom. In the second N3- site, N3- is bonded in a distorted water-like geometry to one Co2+ and one Br2+ atom. The N–Br bond length is 1.90 Å. Br2+ is bonded in a single-bond geometry to one N3- atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on H3CBrClF by Materials Project

CH3ClBrF crystallizes in the orthorhombic Pnma space group. The structure is zero-dimensional and consists of four bromine fluoride molecules and four chloromethane molecules.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Nb(Br3O)2 by Materials Project

NbBr4O2(Br)2 crystallizes in the orthorhombic Pmn2_1 space group. The structure is zero-dimensional and consists of two bromine molecules, two hydrogen peroxide molecules, and two tetrabromoniobium molecules.

36 MATERIALS SCIENCE↗
DOE OSTI2023

Phase I Final Technical Report _ RDUSA

During Phase I of this proposal our team focused on meeting the goals proposed in the Phase I project which included identifying the integration approaches and fundamental materials properties (composition, bonding, defects, structure, doping, etc.) defining response to X-ray energies between 10-100KeV and sensitivity >100 μC Gyair-1 cm-2 in perovskite systems with formula CsPbX3 and CsPb2X5 [where X = chlorine (Cl), bromine (Br), iodine (I), or a combination of any of these elements] to enable high-efficiency, low-cost, X-ray detection systems. In the sections below, we summarize the research results that confirm the feasibility of our technical approach. In summary, we have demonstrated X-ray sensitivity >500 μC Gyair-1 cm-2 in the energy range of 10-100 keV using CsPbBr3 films of thicknesses ranging from 8 μm to 500 μm, which is above the technical requirements outlined in the call for proposal.

36 MATERIALS SCIENCE↗