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All sourcesNASA NTRSDOE OSTI
DOE OSTI2020

Materials Data on B2O3 by Materials Project

B2O3 crystallizes in the trigonal P3_121 space group. The structure is three-dimensional. B3+ is bonded in a trigonal planar geometry to three O2- atoms. There are a spread of B–O bond distances ranging from 1.37–1.39 Å. There are two inequivalent O2- sites. In the first O2- site, O2- is bonded in a bent 150 degrees geometry to two equivalent B3+ atoms. In the second O2- site, O2- is bonded in a bent 120 degrees geometry to two equivalent B3+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on B2O3 by Materials Project

B2O3 crystallizes in the orthorhombic Cmc2_1 space group. The structure is three-dimensional. B3+ is bonded to four O2- atoms to form corner-sharing BO4 tetrahedra. There are a spread of B–O bond distances ranging from 1.38–1.53 Å. There are two inequivalent O2- sites. In the first O2- site, O2- is bonded in a bent 150 degrees geometry to two equivalent B3+ atoms. In the second O2- site, O2- is bonded in a trigonal planar geometry to three equivalent B3+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Cs2(B2O3)9 by Materials Project

Cs2(B2O3)9 crystallizes in the monoclinic P2_1 space group. The structure is three-dimensional. there are two inequivalent Cs sites. In the first Cs site, Cs is bonded in a 10-coordinate geometry to ten O atoms. There are a spread of Cs–O bond distances ranging from 3.15–3.61 Å. In the second Cs site, Cs is bonded in a 10-coordinate geometry to ten O atoms. There are a spread of Cs–O bond distances ranging from 3.15–3.61 Å. There are eighteen inequivalent B sites. In the first B site, B is bonded in a bent 120 degrees geometry to two O atoms. There is one shorter (1.38 Å) and one longer (1.40 Å) B–O bond length. In the second B site, B is bonded in a trigonal planar geometry to three O atoms. There are a spread of B–O bond distances ranging from 1.36–1.39 Å. In the third B site, B is bonded in a trigonal planar geometry to three O atoms. There are a spread of B–O bond distances ranging from 1.36–1.40 Å. In the fourth B site, B is bonded in a trigonal planar geometry to three O atoms. There are a spread of B–O bond distances ranging from 1.34–1.40 Å. In the fifth B site, B is bonded in a trigonal planar geometry to three O atoms. There are a spread of B–O bond distances ranging from 1.33–1.41 Å. In the sixth B site, B is bonded in a trigonal planar geometry to three O atoms. There are a spread of B–O bond distances ranging from 1.33–1.43 Å. In the seventh B site, B is bonded in a bent 120 degrees geometry to two O atoms. There is one shorter (1.38 Å) and one longer (1.40 Å) B–O bond length. In the eighth B site, B is bonded in a trigonal planar geometry to three O atoms. There are a spread of B–O bond distances ranging from 1.36–1.39 Å. In the ninth B site, B is bonded in a trigonal planar geometry to three O atoms. There are a spread of B–O bond distances ranging from 1.33–1.41 Å. In the tenth B site, B is bonded in a trigonal planar geometry to three O atoms. There are a spread of B–O bond distances ranging from 1.33–1.43 Å. In the eleventh B site, B is bonded in a trigonal planar geometry to three O atoms. There are a spread of B–O bond distances ranging from 1.36–1.40 Å. In the twelfth B site, B is bonded in a trigonal planar geometry to three O atoms. There are a spread of B–O bond distances ranging from 1.34–1.40 Å. In the thirteenth B site, B is bonded in a tetrahedral geometry to four O atoms. All B–O bond lengths are 1.48 Å. In the fourteenth B site, B is bonded in a tetrahedral geometry to four O atoms. All B–O bond lengths are 1.49 Å. In the fifteenth B site, B is bonded in a trigonal planar geometry to three O atoms. There is one shorter (1.34 Å) and two longer (1.39 Å) B–O bond length. In the sixteenth B site, B is bonded in a trigonal planar geometry to three O atoms. There are a spread of B–O bond distances ranging from 1.35–1.40 Å. In the seventeenth B site, B is bonded in a trigonal planar geometry to three O atoms. There is one shorter (1.35 Å) and two longer (1.39 Å) B–O bond length. In the eighteenth B site, B is bonded in a trigonal planar geometry to three O atoms. There is one shorter (1.34 Å) and two longer (1.39 Å) B–O bond length. There are twenty-seven inequivalent O sites. In the first O site, O is bonded in a bent 120 degrees geometry to one Cs and two B atoms. In the second O site, O is bonded in a bent 120 degrees geometry to one Cs and two B atoms. In the third O site, O is bonded in a bent 150 degrees geometry to two B atoms. In the fourth O site, O is bonded in a bent 120 degrees geometry to two B atoms. In the fifth O site, O is bonded in a bent 120 degrees geometry to two B atoms. In the sixth O site, O is bonded in a bent 120 degrees geometry to one Cs and two B atoms. In the seventh O site, O is bonded in a bent 120 degrees geometry to one Cs and two B atoms. In the eighth O site, O is bonded in a bent 120 degrees geometry to two B atoms. In the ninth O site, O is bonded in a bent 120 degrees geometry to two B atoms. In the tenth O site, O is bonded in a bent 120 degrees geometry to one Cs and two B atoms. In the eleventh O site, O is bonded in a bent 120 degrees geometry to one Cs and two B atoms. In the twelfth O site, O is bonded in a bent 150 degrees geometry to one Cs and two B atoms. In the thirteenth O site, O is bonded in a bent 150 degrees geometry to one Cs and two B atoms. In the fourteenth O site, O is bonded in a bent 120 degrees geometry to one Cs and two B atoms. In the fifteenth O site, O is bonded in a distorted bent 120 degrees geometry to one Cs and two B atoms. In the sixteenth O site, O is bonded in a bent 120 degrees geometry to one Cs and two B atoms. In the seventeenth O site, O is bonded in a distorted bent 120 degrees geometry to one Cs and two B atoms. In the eighteenth O site, O is bonded in a bent 120 degrees geometry to one Cs and two B atoms. In the nineteenth O site, O is bonded in a bent 120 degrees geometry to one Cs and two B atoms. In the twentieth O site, O is bonded in a bent 120 degrees geometry to one Cs and two B atoms. In the twenty-first O site, O is bonded in a bent 120 degrees geometry to one Cs and two B atoms. In the twenty-second O site, O is bonded in a bent 150 degrees geometry to one Cs and two B atoms. In the twenty-third O site, O is bonded in a bent 150 degrees geometry to one Cs and two B atoms. In the twenty-fourth O site, O is bonded in a bent 120 degrees geometry to two B atoms. In the twenty-fifth O site, O is bonded in a bent 120 degrees geometry to two B atoms. In the twenty-sixth O site, O is bonded in a bent 120 degrees geometry to one Cs and two B atoms. In the twenty-seventh O site, O is bonded in a bent 120 degrees geometry to one Cs and two B atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Coated U3Si2 pellets with enhanced water and steam oxidation resistance

A method of forming a water resistant boundary on a fissile material for use in a water cooled nuclear reactor is described. The method comprises coating the fissile material, such as a pellet of U3Si2 and/or the grain boundaries, to a desired thickness with a suitable coating material, such as atomic layer deposition or a thermal spray process. The coating material may be any non-reactive material with a solubility at least as low as that of UO2. Exemplary coating materials include ZrSiO4, FeCrAl, Cr, Zr, Al—Cr, CrAl, ZrO2, CeO2, TiO2, SiO2, UO2, ZrB2, Na2O—B2O3—SiO2—Al2O3 glass, Al2O3, Cr2O3, carbon, and SiC, and combinations thereof. The water resistant layer may be overlayed with a burnable absorber layer, such as ZrB2 or B2O3—SiO2 glass.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗
DOE OSTI2023

Dynamically Formed Active Sites on Liquid Boron Oxide for Selective Oxidative Dehydrogenation of Propane

Boron-based catalysts have been shown to be both active and selective for driving the oxidative dehydrogenation of propane (ODHP) without the use of precious metals. This reaction occurs at temperatures that melt the oxide catalyst which challenges our ability to identify the liquid structures of the boron oxide phase under reaction conditions, hindering the understanding of its active sites and reaction mechanism. By combining ab initio molecular dynamics simulation, in-situ Raman characterization, and microkinetic modeling, we propose that the di-coordinated boron sites (BO2) in liquid boron oxide are the active species for O2 activation under reaction conditions. The formed peroxy-like species (>B-O-O-B<) can be viewed as a moderate oxidant for ODHP. The dynamical >B-O* dangling bond originated from >B-O-O-B< site as well as the liquid B2O3 structure itself, plays a critical role in the abstraction of H atoms from propane (C3H7 radical formation). Microkinetic modeling reveals C3H7 radical formation to be the main rate controlling step (~75% degree of rate control) with the dehydration of boron hydroxyls (B-OHs) to recover the di-coordinated boron active sites controlling the remainder of the rate (~25% degree of rate control). Moreover, the activation barriers are found to strongly depend upon the surface B-OH concentration. These findings provide significant insights into the active site and reaction mechanisms on boron-based catalysts for ODHP and underlie the importance of understanding the liquid nature of the catalyst to account for the catalytic activity.

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

Glass-bonded ceramic waste forms for immobilization of radioiodine from caustic scrubber wastes

Glass-bonded sodalite composite waste forms have been developed for the immobilization of liquid radioactive wastes resulting from off-gas treatment during aqueous reprocessing of used nuclear fuel, with a particular focus on 129I. The proposed composite waste form is comprised of aluminosilicate ceramic phases containing volatile radionuclides bonded with a glassy matrix. In this work, a suite of ten candidate low-temperature glass binders (ZnO-Bi2O3-based glasses and a Na2O-B2O3-SiO2 glass) were examined. Six glasses were mixed with caustic scrubber waste simulant previously converted into a sodalite-rich material (to provide glass fractions of 10 and 20 wt.%), uniaxially pressed into pellets, and sintered at 350 °C or 550 °C for 8 h in air. Iodine retention after heat treatment was assessed by neutron activation analysis, showing retention of 67-100 % of expected iodine. The aqueous durabilities of the resulting materials were then determined, following the ASTM C1308 standard test, showing iodine releases of 1 to 23 g m-2 after 4 d. The cumulative iodine release for the best performing system (a zinc-bismuth-borate glass binder) was <1 g m-2, and its iodine retention from processing was 67 %. The iodine releases compared favorably with other waste forms. In parallel, this best-performing composition was also consolidated via hot isostatic pressing (HIP) in a stainless-steel canister at 550 °C for 2 h under 100 MPa pressure. The HIPed sample was produced at the ~20 g scale and showed improved densification and minimal reaction with the canister.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗
DOE OSTI2026

Effects of B 2 O 3 on the Growth, Structural, and Magneto-Optical Properties of Yttrium Iron Garnet Single-Crystal Fibers

This study explores the fabrication of yttrium iron garnet (YIG) single crystal fibers using the laser heated pedestal growth (LHPG) method with the experimental addition of B 2 O 3 . The incorporation of B 2 O 3 facilitates the fiber fabrication process by lowering the required growth temperatures and likely modifying melt viscosity behavior, consistent with the established fluxing behavior of B2O3 and the comparative viscosity trend observed in the TMA−VFT analysis, thereby improving process efficiency while maintaining fiber quality. Structural characterization using EBSD and SC-XRD reveals a transition from polycrystalline to single-crystal behavior, with improved alignment along the [111] direction without altering the garnet structure. Magnetic measurements show increases in saturation magnetization in B 2 O 3 -assisted fibers. Three-dimensional anisotropy energy modeling, based on EBSD-derived Euler angles, indicates that the enhanced crystallinity and orientation contribute to reorientation of MCA energy distribution due to improved crystallographic alignment. Faraday rotation measurements show that the B 2 O 3 -assisted sample exhibits a rotation angle closer to reported values for high-quality YIG, suggesting improved phase purity and crystallographic quality. These findings demonstrate that B 2 O 3 -assisted LHPG growth is a scalable and nontoxic approach to producing high-performance YIG fibers for integrated photonic and magnetic field sensing applications.

Crystal structure↗
DOE OSTI2025

First-Principles Simulations Correlating X-ray Absorption Spectroscopy Features to Point Defects in h -BN

Hexagonal boron nitride (h-BN) is a promising material for a range of emerging applications in electronics, quantum information technology, and energy storage. Soft X-ray absorption spectroscopy (XAS) is powerful to reveal atomic details of BN, especially in the presence of defects. However, correlating XAS spectral features with specific defect types remains elusive. In this Letter, we report B K-edge XAS measurements of sputter-deposited turbostratic h-BN films and use a combination of first-principles spectroscopic simulations and analysis of detailed electronic structure and local charge transfer characteristics to elucidate their unique spectroscopic features. Our results show that the two main defect-related peaks, between the main π* resonances of h-BN and B2O3, as typically observed in BN films deposited by energetic condensation or bombarded with energetic ions, are associated with electronic states of H-passivated B atoms bonded to one and two oxygen impurity atoms, respectively. These conclusions hold significant implications for applications relying on defect-mediated properties of h-BN.

chemical structure↗