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9 records
All sourcesNASA NTRSDOE OSTI
DOE OSTI2023

The Structure of Boron Monoxide

Boron monoxide (BO), prepared by the thermal condensation of tetrahydroxydiboron, was first reported in 1955; however, its structure could not be determined. With the recent attention on boron-based two-dimensional materials, such as borophene and hexagonal boron nitride, there is renewed interest in BO. A large number of stable BO structures have been computationally identified, but none are supported by experiments. The consensus is that the material likely forms a boroxine-based two-dimensional material. Herein, we apply advanced 11 B NMR experiments to determine the relative orientations of B(B)O 2 centers in BO. We find that the material is composed of D 2h -symmetric O 2 B–BO 2 units that organize to form larger B 4 O 2 rings. Further, powder diffraction experiments additionally reveal that these units organize to form two-dimensional layers with a random stacking pattern. This observation is in agreement with earlier density functional theory (DFT) studies that showed B 4 O 2 -based structures to be the most stable.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2025

Boron monoxide is a one-dimensional polymer

It was recently reported that boron monoxide (BO) is formed through the cross-linking of B 4 O 2 structural building units. Multiple theoretical phases agree with this description. Using pycnometry, multidimensional 17 O NMR spectroscopy, and plane-wave DFT calculations we determined the likely polymorph to be a one-dimensional polymer initially proposed in 1955.

Thuma, Joseph F. [Iowa State Univ., Ames, IA (Unit↗
DOE OSTI2020

Materials Data on CaGaBiB2O7 by Materials Project

CaGaBBiO6BO crystallizes in the tetragonal P-42_1m space group. The structure is three-dimensional and consists of four boron monoxide molecules and one CaGaBBiO6 framework. In the CaGaBBiO6 framework, Ca2+ is bonded to six O2- atoms to form distorted CaO6 octahedra that share a cornercorner with one CaO6 octahedra, a cornercorner with one BO4 tetrahedra, corners with two equivalent GaO4 tetrahedra, and edges with two equivalent BO4 tetrahedra. The corner-sharing octahedral tilt angles are 74°. There are a spread of Ca–O bond distances ranging from 2.24–2.66 Å. There are two inequivalent Ga3+ sites. In the first Ga3+ site, Ga3+ is bonded to four equivalent O2- atoms to form GaO4 tetrahedra that share corners with four equivalent CaO6 octahedra and corners with four equivalent BO4 tetrahedra. The corner-sharing octahedral tilt angles are 67°. All Ga–O bond lengths are 1.91 Å. In the second Ga3+ site, Ga3+ is bonded in a 4-coordinate geometry to four equivalent O2- atoms. All Ga–O bond lengths are 1.89 Å. B3+ is bonded to four O2- atoms to form BO4 tetrahedra that share a cornercorner with one CaO6 octahedra, a cornercorner with one BO4 tetrahedra, corners with two equivalent GaO4 tetrahedra, and edges with two equivalent CaO6 octahedra. The corner-sharing octahedral tilt angles are 48°. There are a spread of B–O bond distances ranging from 1.43–1.55 Å. Bi3+ is bonded in a 1-coordinate geometry to seven O2- atoms. There are a spread of Bi–O bond distances ranging from 2.13–2.90 Å. There are five inequivalent O2- sites. In the first O2- site, O2- is bonded in a 1-coordinate geometry to one Ca2+, one Ga3+, one Bi3+, and one O2- atom. The O–O bond length is 1.59 Å. In the second O2- site, O2- is bonded in a water-like geometry to two equivalent Bi3+ atoms. In the third O2- site, O2- is bonded in a 1-coordinate geometry to one Ca2+, one B3+, and two equivalent Bi3+ atoms. In the fourth O2- site, O2- is bonded in a 4-coordinate geometry to one Ca2+, one Ga3+, one B3+, and one Bi3+ atom. In the fifth O2- site, O2- is bonded in a 4-coordinate geometry to two equivalent Ca2+ and two equivalent B3+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Cs(BO)12 by Materials Project

Cs(BO)6(BO)6 crystallizes in the trigonal R-3m space group. The structure is zero-dimensional and consists of eighteen boron monoxide molecules and three Cs(BO)6 clusters. In each Cs(BO)6 cluster, Cs is bonded in a hexagonal planar geometry to six equivalent O atoms. All Cs–O bond lengths are 3.26 Å. B is bonded in a single-bond geometry to one O atom. The B–O bond length is 1.26 Å. O is bonded in a single-bond geometry to one Cs and one B atom.

36 MATERIALS SCIENCE↗
NASA NTRS1999

Continuous method of producing silicon carbide fibers

This invention pertains to a method for production of polycrystalline ceramic fibers from silicon oxycarbide (SiCO) ceramic fibers wherein the method comprises heating an amorphous ceramic fiber containing silicon and carbon in an inert environment comprising a boron oxide and carbon monoxide at a temperature sufficient to convert the amorphous ceramic fiber to a polycrystalline ceramic fiber. By having carbon monoxide present during the heating of the ceramic fiber, it is possible to achieve higher production rates on a continuous process.

Barnard, Thomas Duncan↗
DOE OSTI2021

One‐Pot Synthesis of Xanthone by Carbonylative Suzuki Coupling Reaction

Abstract Xanthone derivatives have a dibenzo‐y‐pyrone scaffold which has gained great interest in Medicinal Chemistry due to their diverse biological activities. Usually, its synthesis requires multi‐step synthetic routes using harsh conditions and high catalyst loadings. In this communication, we report for the first time a one‐pot synthesis of the xanthone scaffold based on a carbonylative Suzuki coupling. Iodophenol and (2‐methoxyphenyl)boronic acid were coupled under carbon monoxide, generated from a carbon monoxide surrogate. An experimental data‐based model was built to guide the reaction optimization. The optimized conditions were 1 mol% of a pincer complex as palladium catalyst, 5 equivalents of K 2 CO 3 as base, and DMF:water (7 : 3) as solvent. The robustness of the synthetic method, namely in terms of the reactants scope, was also evaluated. This approach provided the xanthone scaffold in high yields and provided a deep insight into the carbonylative Suzuki couplings.

Loureiro, Daniela R. P.↗
NASA NTRS1987

Silicon carbide sintered body manufactured from silicon carbide powder containing boron, silicon and carbonaceous additive

A silicon carbide powder of a 5-micron grain size is mixed with 0.15 to 0.60 wt% mixture of a boron compound, i.e., boric acid, boron carbide (B4C), silicon boride (SiB4 or SiB6), aluminum boride, etc., and an aluminum compound, i.e., aluminum, aluminum oxide, aluminum hydroxide, aluminum carbide, etc., or aluminum boride (AlB2) alone, in such a proportion that the boron/aluminum atomic ratio in the sintered body becomes 0.05 to 0.25 wt% and 0.05 to 0.40 wt%, respectively, together with a carbonaceous additive to supply enough carbon to convert oxygen accompanying raw materials and additives into carbon monoxide.

Tanaka, Hidehiko↗
NASA NTRS1979

Method of purifying metallurgical grade silicon employing reduced pressure atmospheric control

A method in which a quartz tube is charged with chunks of metallurgical grade silicon and/or a mixture of such chunks and high purity quartz sand, and impurities from a class including aluminum, boron, as well as certain transition metals including nickel, iron, and manganese is described. The tube is then evacuated and heated to a temperature within a range of 800 C to 1400 C. A stream of gas comprising a reactant, such as silicon tetrafluoride, is continuously delivered at low pressures through the charge for causing a metathetical reaction of impurities of the silicon and the reactant to occur for forming a volatile halide and leaving a residue of silicon of an improved purity. The reactant which included carbon monoxide gas and impurities such as iron and nickel react to form volatile carbonyls.

Ingle, W. M.↗
DOE OSTI2025

Prediction of an alternative high-pressure route to polymeric carbon dioxide as a metastable energetic material

The use of pressure to obtain new materials that can be recovered under ambient conditions is a central problem in high-pressure physics. Despite decades of research, this goal has only been achieved in the laboratory for a few notable examples, such as diamond and cubic boron nitride. An area of significant interest is the transformation under compression of light-element molecular compounds to extended covalent-bonded (polymeric) solids. Among them, CO 2 has been extensively studied because of its status as a prototypical simple molecular system with a rich phase diagram and due to its fundamental role in Earth’s physics and chemistry. One of its polymeric crystalline phases, accessible at extreme pressures and temperatures, has been recently quenched to ambient pressure, but below room temperature. Here we report ab initio calculations predicting that isothermal compression of a carbon monoxide and oxygen mixture (CO+O 2 ), rather than the compound CO 2 , lowers the onset of C-polymerization at room temperature from ~ 118 GPa to ~ 7 GPa (complete by ~ 23 GPa). Moreover, it leads to the formation of an intrinsically different polymer with enhanced metastability. We predict that this dense phase is an energetic material which can potentially be recovered to ambient pressure and temperature.

Paul, Reetam [Lawrence Livermore National Laborato↗