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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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18 records
All sourcesNASA NTRSDOE OSTI
DOE OSTI2025

Machine learning guided search for energetically favorable metal borocarbide ternary compounds

In this work, we employ machine-learning (ML) combined with first principles calculations to efficiently search for the energetically favorable metal borocarbide (M-B-C) ternary compounds with M being the group 1–3 metal elements. Using a crystal graph convolutional neural network (CGCNN) ML approach followed by first-principles calculations, we predicted 47 energetically favorable stable and metastable ternary Na-B-C, Ca-B-C, and La-B-C ternary compounds with their decomposition energy (E d ) below or within 100 meV/atom from the currently known convex hulls. Phonon spectra and electronic structures of the 14 energetically favorable stable structures are also investigated by first-principles calculations. By substituting the metal atoms in the 29 energetically favorable non-equivalent template structures of Na (Ca, La)-B-C with other group 1–3 elements in the periodic table, we further obtain 22 stable structures and 52 metastable structures (E d ≤100 meV/atom with respect to the known convex hulls) for Li-B-C, K-B-C, Rb-B-C, Mg-B-C, Sr-B-C, Ba-B-C, Sc-B-C and Y-B-C ternary compounds. New convex hulls including our newly predicted stable ternary structures and the known stable structures are constructed for the M-B-C systems. The results obtained by our ML guided first-principles calculations enrich our knowledge in the structure and energy landscape of metal borocarbide ternary compounds and provide useful guidance for further experimental synthesis and discovery.

36 MATERIALS SCIENCE↗
DOE OSTI2024

Integrated modeling of boron powder injection for real-time plasma-facing component conditioning

An integrated modeling framework for investigating the application of solid boron (B) powder injection for real-time surface conditioning of plasma-facing components (PFCs) in tokamak environments is presented. Utilizing the DIII-D impurity powder dropper (IPD) setup, this study simulates B powder injection scenarios ranging from milligrams to tens of milligrams per second, corresponding to boron flux rates of 10 20 –10 21 B/s in standard L-mode conditions. The comprehensive modeling approach combines EMC3-EIRENE for simulating the deuterium plasma background and the Dust Injection Simulator (DIS) for the ablation and transport of the boron powder particles. EMC3 trace impurity fluid modeling results show substantial boron transport to the inboard lower divertor, predominantly influenced by the main ion plasma flow. The dependency on powder particle size (5-250 µm) was found to be insignificant for the scenario considered. The effects of erosion and redeposition were considered to reconcile the discrepancies with experimental observations, which saw substantial deposition on the outer divertor plasma-facing components. For this purpose, the WallDYN3D code was updated to include boron sources within the plasma domain and integrated into the modeling framework. The mixed-material migration modeling shows evolving boron deposition patterns, suggesting the formation of mixed B-C layers or predominantly B coverage depending on the powder mass flow rate. While the modeling outcomes at lower B injection rates tend to align with DIII-D experimental observations, the prediction of near-pure boron layers at higher rates has yet to be experimentally verified in the carbon environment of the DIII-D tokamak. The extensive reach of boron layers found in the modeling suggests the need for modeling that encompasses the entire wall geometry for more accurate experimental correlations. This integrated approach sets a precedent for analyzing and applying real-time in-situ boron coating techniques in advanced tokamak scenarios, potentially extendable to ITER.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2020

Direct functionalization of C-H bonds by electrophilic anions

Bond formation between two of the most inert molecules, alkanes and [B12X12]2- (X = Cl, Br), is performed in a two step process. Fragmentation of [B12X12]2- in the gas phase generates highly reactive [B12X11]- ions which spontaneously react with alkanes. The reaction mechanism was investigated using tandem mass spectrometry and gas-phase vibrational spectroscopy combined with electronic structure calculations. This effort revealed the unprecedented and counterintuitive electrophilic substitution of a proton in an alkane by a negatively charged ion resulting in a B-C bond formation. The product is a dianionic [B12X11CnH2n+1]2- species, in which H+ is electrostatically bound to the dianion. High flux ion soft-landing was performed to co-deposit [B12X11]- and complex organic molecules (phthalates) in thin layers on surfaces. Molecular structure analysis of the product films revealed that C-H functionalization by [B12X11]- occured in the presence of other more reactive functional groups. This observation demonstrates the utility of highly reactive fragment ions for defined bond formation processes and may pave the way to the use of gas phase ion chemistry for chemical synthesis in the condensed phase.

Warneke, Jonas↗
DOE OSTI2020

Observations of wall conditioning by means of boron powder injection in DIII-D H-mode plasmas

In this paper, we report observations from the DIII-D tokamak indicating that boron (B) powder injection in tokamak plasmas improves wall conditions similarly to glow discharge boronization (GDB). Isotopically enriched B powder (B 11 > 95%) was introduced gravitationally in a sequence of H-mode plasma discharges at rates up to ~160 mg s -1 for durations up to 3 s. Boron injection to cumulative amounts ≤0.1 g appeared to improve wall conditions similarly to boronization, with indications of reduced wall fueling, reduced recycling at the outer strike point and reduced impurity content at breakdown. Post-mortem analysis of graphite samples exposed to far scrape-off layer plasma fluxes during boron injection confirm the formation of a B-C layer, with average surface composition B:C ~ 1. The results suggest that injecting boron-rich powders in tokamak plasmas can effectively replenish boron films on carbon plasma facing components to improve wall conditions and extend the duration of the beneficial effects of GDB.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2023

Superconductivity in the Li-B-C system at 100 GPa

Layer Li-B-C compounds have been shown to have feasible superconductivity. Using the adaptive genetic algorithm, we predict the structures of the Li-B-C system at 100 GPa. Here we identify several low-enthalpy metallic phases with stoichiometries of Li B 2 C, Li B 3 C, Li 2 BC 2 , Li 3 B 2 C 3 , Li 3 BC, and Li 5 BC. Using a fast screening method of electron-phonon interaction, we find that Li B 3 C is a promising candidate for superconductivity. The consecutive calculations using the full Brillouin zone confirm the existence of the strong electron-phonon coupling (EPC) in this system. The anharmonic B-C phonon modes near the zone center provide the major contribution to the EPC. The EPC constant is 1.40, and the estimated critical temperature is 22 K. In this paper, we indicate that superconductivity can also happen without a layered structural motif in the Li-B-C system. We also demonstrate an effective strategy for crystal structure prediction of superconducting materials.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2023

Synthesis and Thermal Oxidation Resistance of Boron-Rich Boron–Carbide Material

A boron-rich boron–carbide material (B4+δC) was synthesized by spark plasma sintering of a ball-milled mixture of high-purity boron powder and graphitic carbon at a pressure of 7 MPa and a temperature of 1930 °C. This high-pressure, high-temperature synthesized material was recovered and characterized by X-ray diffraction, X-ray photoelectron spectroscopy, Raman spectroscopy, Vickers hardness measurements, and thermal oxidation studies. The X-ray diffraction studies revealed a single-phase rhombohedral structure (space group R-3m) with lattice parameters in hexagonal representation as a = 5.609 ± 0.007 Å and c = 12.082 ± 0.02 Å. The experimental lattice parameters result in a value of δ = 0.55, or the composition of the synthesized compound as B4.55C. The high-resolution scans of boron binding energy reveal the existence of a B-C bond at 188.5 eV. Raman spectroscopy reveals the existence of a 386 cm−1 vibrational mode representative of C-B-B linear chain formation due to excess boron in the lattice. The measured Vickers microhardness at a load of 200 gf shows a high hardness value of 33.8 ± 2.3 GPa. Thermal gravimetric studies on B4.55C were conducted at a temperature of 1300 °C in a compressed dry air environment, and its behavior is compared to other high-temperature ceramic materials such as high-entropy transition metal boride. The high neutron absorption cross section, high melting point, high mechanical strength, and thermal oxidation resistance make this material ideal for applications in extreme environments.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on BC by Materials Project

BC1 is Wurtzite structured and crystallizes in the hexagonal P6_3mc space group. The structure is three-dimensional. B3+ is bonded to four equivalent C3- atoms to form corner-sharing BC4 tetrahedra. There is one shorter (1.57 Å) and three longer (1.68 Å) B–C bond length. C3- is bonded to four equivalent B3+ atoms to form corner-sharing CB4 tetrahedra.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on B4C by Materials Project

B4C crystallizes in the trigonal R-3m space group. The structure is three-dimensional. there are two inequivalent B sites. In the first B site, B is bonded in a distorted single-bond geometry to two B and one C atom. Both B–B bond lengths are 1.71 Å. The B–C bond length is 1.64 Å. In the second B site, B is bonded in a 5-coordinate geometry to five B atoms. There is two shorter (1.77 Å) and two longer (1.79 Å) B–B bond length. There are two inequivalent C sites. In the first C site, C is bonded to three equivalent B and one C atom to form distorted corner-sharing CB3C tetrahedra. The C–C bond length is 1.31 Å. In the second C site, C is bonded in a linear geometry to two equivalent C atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on B13C2 by Materials Project

B13C2 crystallizes in the trigonal R-3m space group. The structure is three-dimensional. there are three inequivalent B sites. In the first B site, B is bonded in a linear geometry to two equivalent C atoms. Both B–C bond lengths are 1.44 Å. In the second B site, B is bonded in a single-bond geometry to three equivalent B and one C atom. There is one shorter (1.79 Å) and two longer (1.82 Å) B–B bond length. The B–C bond length is 1.61 Å. In the third B site, B is bonded in a 6-coordinate geometry to six B atoms. There is one shorter (1.77 Å) and two longer (1.79 Å) B–B bond length. C is bonded to four B atoms to form corner-sharing CB4 trigonal pyramids.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on B4C by Materials Project

B4C crystallizes in the trigonal R-3m space group. The structure is three-dimensional. there are two inequivalent B sites. In the first B site, B is bonded in a distorted single-bond geometry to three equivalent B and one C atom. All B–B bond lengths are 1.79 Å. The B–C bond length is 1.66 Å. In the second B site, B is bonded in a 6-coordinate geometry to six B atoms. There is one shorter (1.72 Å) and two longer (1.83 Å) B–B bond length. There are two inequivalent C sites. In the first C site, C is bonded in a linear geometry to two equivalent C atoms. Both C–C bond lengths are 1.33 Å. In the second C site, C is bonded to three equivalent B and one C atom to form corner-sharing CB3C tetrahedra.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on B4C by Materials Project

B4C crystallizes in the trigonal R-3m space group. The structure is three-dimensional. there are two inequivalent B sites. In the first B site, B is bonded in a single-bond geometry to two equivalent B and one C atom. There is one shorter (1.57 Å) and one longer (1.90 Å) B–B bond length. The B–C bond length is 1.61 Å. In the second B site, B is bonded in a 4-coordinate geometry to four B atoms. Both B–B bond lengths are 1.65 Å. There are two inequivalent C sites. In the first C site, C is bonded in a linear geometry to two equivalent C atoms. Both C–C bond lengths are 1.38 Å. In the second C site, C is bonded to three equivalent B and one C atom to form distorted corner-sharing CB3C tetrahedra.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on BC5 by Materials Project

BC5 crystallizes in the trigonal P3m1 space group. The structure is three-dimensional. B3+ is bonded to four C+0.60- atoms to form BC4 tetrahedra that share corners with six equivalent BC4 tetrahedra and corners with six CC4 tetrahedra. There is one shorter (1.61 Å) and three longer (1.63 Å) B–C bond length. There are five inequivalent C+0.60- sites. In the first C+0.60- site, C+0.60- is bonded to one B3+ and three equivalent C+0.60- atoms to form corner-sharing CBC3 tetrahedra. All C–C bond lengths are 1.56 Å. In the second C+0.60- site, C+0.60- is bonded to four C+0.60- atoms to form CC4 tetrahedra that share corners with three equivalent BC4 tetrahedra and corners with nine CC4 tetrahedra. The C–C bond length is 1.55 Å. In the third C+0.60- site, C+0.60- is bonded to four C+0.60- atoms to form CC4 tetrahedra that share corners with three equivalent BC4 tetrahedra and corners with nine CC4 tetrahedra. There is one shorter (1.50 Å) and three longer (1.57 Å) C–C bond length. In the fourth C+0.60- site, C+0.60- is bonded to four C+0.60- atoms to form corner-sharing CC4 tetrahedra. In the fifth C+0.60- site, C+0.60- is bonded to three equivalent B3+ and one C+0.60- atom to form distorted corner-sharing CB3C tetrahedra.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on BC7 by Materials Project

BC7 crystallizes in the cubic P-43m space group. The structure is three-dimensional. B3+ is bonded to four equivalent C+0.43- atoms to form BC4 tetrahedra that share corners with twelve equivalent CC4 tetrahedra. All B–C bond lengths are 1.60 Å. There are two inequivalent C+0.43- sites. In the first C+0.43- site, C+0.43- is bonded to four equivalent C+0.43- atoms to form CC4 tetrahedra that share corners with four equivalent BC4 tetrahedra and corners with eight equivalent CC4 tetrahedra. All C–C bond lengths are 1.56 Å. In the second C+0.43- site, C+0.43- is bonded to one B3+ and three equivalent C+0.43- atoms to form distorted corner-sharing CBC3 tetrahedra.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on BC7 by Materials Project

BC7 is beta beryllia-like structured and crystallizes in the tetragonal P-4m2 space group. The structure is three-dimensional. B3+ is bonded to four equivalent C+0.43- atoms to form BC4 tetrahedra that share corners with four equivalent BC4 tetrahedra and corners with eight equivalent CC4 tetrahedra. All B–C bond lengths are 1.65 Å. There are four inequivalent C+0.43- sites. In the first C+0.43- site, C+0.43- is bonded to four equivalent C+0.43- atoms to form corner-sharing CC4 tetrahedra. All C–C bond lengths are 1.54 Å. In the second C+0.43- site, C+0.43- is bonded to four C+0.43- atoms to form corner-sharing CC4 tetrahedra. Both C–C bond lengths are 1.56 Å. In the third C+0.43- site, C+0.43- is bonded to two equivalent B3+ and two equivalent C+0.43- atoms to form corner-sharing CB2C2 tetrahedra. Both C–C bond lengths are 1.53 Å. In the fourth C+0.43- site, C+0.43- is bonded to four C+0.43- atoms to form CC4 tetrahedra that share corners with four equivalent BC4 tetrahedra and corners with eight CC4 tetrahedra.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on BC by Materials Project

BC1 is Boron Nitride-like structured and crystallizes in the hexagonal P-6m2 space group. The structure is two-dimensional and consists of one BC1 sheet oriented in the (0, 0, 1) direction. B3+ is bonded in a trigonal planar geometry to three equivalent C3- atoms. All B–C bond lengths are 1.55 Å. C3- is bonded in a trigonal planar geometry to three equivalent B3+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on BC5 by Materials Project

BC5 crystallizes in the orthorhombic Imm2 space group. The structure is three-dimensional. B3+ is bonded to four C+0.60- atoms to form BC4 tetrahedra that share corners with two equivalent BC4 tetrahedra and corners with ten equivalent CC4 tetrahedra. There is two shorter (1.61 Å) and two longer (1.68 Å) B–C bond length. There are three inequivalent C+0.60- sites. In the first C+0.60- site, C+0.60- is bonded to one B3+ and three equivalent C+0.60- atoms to form distorted corner-sharing CBC3 tetrahedra. There is two shorter (1.54 Å) and one longer (1.56 Å) C–C bond length. In the second C+0.60- site, C+0.60- is bonded to four C+0.60- atoms to form CC4 tetrahedra that share corners with five equivalent BC4 tetrahedra and corners with seven equivalent CC4 tetrahedra. The C–C bond length is 1.53 Å. In the third C+0.60- site, C+0.60- is bonded to two equivalent B3+ and two equivalent C+0.60- atoms to form distorted corner-sharing CB2C2 tetrahedra.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on BC5 by Materials Project

BC5 crystallizes in the tetragonal I-4m2 space group. The structure is three-dimensional. B3+ is bonded to four equivalent C+0.60- atoms to form BC4 tetrahedra that share corners with four equivalent BC4 tetrahedra and corners with eight equivalent CC4 tetrahedra. All B–C bond lengths are 1.65 Å. There are three inequivalent C+0.60- sites. In the first C+0.60- site, C+0.60- is bonded to two equivalent B3+ and two equivalent C+0.60- atoms to form corner-sharing CB2C2 tetrahedra. Both C–C bond lengths are 1.53 Å. In the second C+0.60- site, C+0.60- is bonded to four equivalent C+0.60- atoms to form corner-sharing CC4 tetrahedra. All C–C bond lengths are 1.56 Å. In the third C+0.60- site, C+0.60- is bonded to four C+0.60- atoms to form CC4 tetrahedra that share corners with four equivalent BC4 tetrahedra and corners with eight equivalent CC4 tetrahedra.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on B9C by Materials Project

B9C crystallizes in the tetragonal I4/mmm space group. The structure is zero-dimensional and consists of eighteen boron, metallic molecules and two medicinal charcoal molecules.

36 MATERIALS SCIENCE↗