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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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At least 19 records
All sourcesNASA NTRSDOE OSTI
DOE OSTI2018

Long-Term Leaching Effect on Decay Resistance of Wood-Plastic Composites Treated with Boron Compounds

In this study, water absorption, thickness swelling and decay resistance of thermoplastic composites treated with three types of boron compounds was investigated. Spruce wood flour was treated with boric acid (BA), borax (BX) and mixture of BA–BX, and then was reinforced at two loading rate (20 and 40 wt%) in polymer matrix. Decay test of the composites was performed using with a brown rot fungus Coniophora puteana and a white rot fungus Trametes versicolor both for leached and unleached samples. The morphologic evaluations of decayed samples were done by scanning electron microscopy. Composites containing higher wood flour loading resulted in increased water absorption, thickness swelling, weight loss and moisture content. Fungal decay susceptibility of WPCs was influenced by leaching test for 60 days. Boron compound treated composites showed higher weight loss and moisture content than controls in decay test. All tested performance parameters were considerably increased in BX containing composites.

36 MATERIALS SCIENCE↗
DOE OSTI2019

Ab initio investigation of single-layer high thermal conductivity boron compounds

The discovery and design of materials with large thermal conductivities (κ L ) is important to address future heat management challenges, particularly as devices shrink to the nanoscale. This requires developing novel physical insights into the microscropic interactions and behaviors of lattice vibrations. In this work, we use ab initio phonon Boltzmann transport calculations to derive fundamental understanding of lattice thermal transport in two-dimensional (2D) monolayer hexagonal boron-based compounds, h-BX (X=N, P, As, Sb). Monolayer h-BAs, in particular, possesses structural and dispersion features similar to bulk cubic BAs and 2D graphene, which govern their ultrahigh room temperature κ L (1300 W/m K and 2000–4000 W/m K, respectively), yet here combine to give significantly lower κ L for monolayer h-BAs (400 W/m K at room temperature). This report explores this discrepancy, and thermal transport in the monolayer h-BX systems in general, via comparison of the microscopic mechanisms that govern phonon transport. Specifically we present calculations of phonon dispersions, velocities, scattering phase space and rates, and κ L of h-BX monolayers as a function of temperature, size, defects, and other fundamental parameters. From these calculations, we make predictions of the thermal conductivities of h-BX monolayers, and more generally develop deeper fundamental understanding of phonon thermal transport in 2D and bulk materials.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2024

Ultrathin Boron Growth onto Nanodiamond Surfaces via Electrophilic Boron Precursors

Diamond as a templating substrate is largely unexplored, and the unique properties of diamond, including its large bandgap, thermal conductance, and lack of cytotoxicity, makes it versatile in emergent technologies in medicine and quantum sensing. Surface termination of an inert diamond substrate and its chemical reactivity are key in generating new bonds for nucleation and growth of an overlayer material. Oxidized high-pressure high temperature (HPHT) nanodiamonds (NDs) are largely terminated by alcohols that act as nucleophiles to initiate covalent bond formation when an electrophilic reactant is available. In this work, we demonstrate a templated synthesis of ultrathin boron on ND surfaces using trigonal boron compounds. Boron trichloride (BCl 3 ), boron tribromide (BBr 3 ), and borane (BH 3 ) were found to react with ND substrates at room temperature in inert conditions. BBr 3 and BCl 3 were highly reactive with the diamond surface, and sheet-like structures were produced and verified with electron microscopy. Surface-sensitive spectroscopies were used to probe the molecular and atomic structure of the ND constructs’ surface, and quantification showed the boron shell was less than 1 nm thick after 1–24 h reactions. Observation of the reaction supports a self-terminating mechanism, similar to atomic layer deposition growth, and is likely due to the quenching of alcohols on the diamond surface. X-ray absorption spectroscopy revealed that boron-termination generated midgap electronic states that were originally predicted by density functional theory (DFT) several years ago. DFT also predicted a negative electron surface, which has yet to be confirmed experimentally here. The boron-diamond nanostructures were found to aggregate in dichloromethane and were dispersed in various solvents and characterized with dynamic light scattering for future cell imaging or cancer therapy applications using boron neutron capture therapy (BNCT). The unique templating mechanism based on nucleophilic alcohols and electrophilic trigonal precursors allows for covalent bond formation and will be of interest to researchers using diamond for quantum sensing, additive manufacturing, BNCT, and potentially as an electron emitter.

36 MATERIALS SCIENCE↗
DOE OSTI2019

Solid-state hydrogen rich boron–nitrogen compounds for energy storage

Boron compounds have a rich history in energy storage applications, ranging from high energy fuels for advanced aircraft to hydrogen storage materials for fuel cell applications. In this paper we review some of the aspects of energy storage materials comprised of electron-poor boron materials combined with electron-rich nitrogen elements with the goal of moderate temperature release of hydrogen. The parent compounds of ammonium borohydride, ammonia borane, and diammoniate of diborane provide approaches for storing high gravimetric and volumetric densities of hydrogen. Here we provide a review with a historical perspective and current developments in the area of solid state B and N containing compounds. This review highlights developments in synthesis of ammonia borane and its derivatives over the last 80 years. Thermodynamics and kinetics of hydrogen release in the solid state are discussed. By changing either substituents on the boron and nitrogen atoms or the physical environment by embedding in mesoporous scaffolds, the thermodynamics can be modified to reduce the exothermicity of hydrogen release and minimize formation of volatile impurities. Several mechanistic studies are reviewed identifying the key distinctions between homopolar and heteropolar H 2 release. Strategies for economical and efficient regeneration of the hydrogen storage materials via chemical transformation are critically reviewed. The limited efficiency of these chemical regeneration has limited some of the potential applications.

25 ENERGY STORAGE↗
DOE OSTI2025

Data-Driven Approach for Controlled Icosahedral Boron- Rich Compound Growth

This final technical report summarizes the research accomplishments and research highlights at the end of the funding period. This project aimed to leverage existing and new computational data produced from first-principles and molecular dynamics simulations to understand the thermodynamic, mechanical, and electronic properties of icosahedral boron compounds. The goal is to achieve targeted material properties by controlling the synthesis routes of these boron-rich compounds.

36 MATERIALS SCIENCE↗
DOE OSTI2023

Prediction of superconductivity in metallic boron–carbon compounds from 0 to 100 GPa by high-throughput screening

Boron–carbon compounds have been shown to have feasible superconductivity. In our earlier paper [Zheng et al., Phys. Rev. B, 2023, 107, 014508], we identified a new conventional superconductor of LiB 3 C at 100 GPa. Here, we aim to extend the investigation of possible superconductivity in this structural framework by replacing Li atoms with 27 different cations from periods 3, 4, and 5 under pressures ranging from 0 to 100 GPa. Using the high-throughput screening method of zone-center electron–phonon interaction, we found that ternary compounds like CaB 3 C, SrB 3 C, TiB 3 C, and VB 3 C are promising candidates for superconductivity. The consecutive calculations using the full Brillouin zone confirm that they have a T c of <31 K at moderate pressures. In conclusion, our study demonstrates that fast screening of superconductivity by calculating zone-center electron–phonon coupling strength is an effective strategy for high-throughput identification of new superconductors.

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

High-fidelity Recognition of Organotrifluoroborate Anions (R-BF 3 - ) as Designer Guest Molecules

The recognition of boron compounds is well developed as boronic acids but untapped as organotrifluoroborate anions (R-BF 3 - ). Here, we are exploring the development of these and other designer anions as anion-recognition motifs by considering them as substituted versions of the parent inorganic ion. To this end, we demonstrate strong and reliable binding of organic trifluoroborates, R-BF 3 - , by cyanostar macrocycles that are size-complementary to the inorganic BF 4 - progenitors. We find that recognition is modulated by the substituent's sterics and that the affinities are retained using the common K + salts of R-BF 3 - anions.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2016

Use of Monte Carlo simulation to quantify CIPS risk

Crud Induced Power Shift (CIPS), caused by the accumulation of boron compounds in corrosion product deposits on high power fuel assemblies, is an important operational issue for Pressurized Water Reactors (PWRs). The Boron-induced Offset Analysis (BOA) computer code has been developed by EPRI in collaboration with Westinghouse to help utility engineers avoid onset of CIPS. The code, used with an established procedure, predicts the maximum boron mass that will be accumulated in the upcoming cycle for a given core design and plant chemistry and operating program. The calculated boron mass above a given threshold predicts the risk of CIPS to the upcoming cycle. BOA has been successful in correctly predicting the risk for onset or lack of CIPS in many cycles. However, like most codes modeling complex physical phenomena, it is subject to uncertainties in several of the inputs used to describe these phenomena. The current BOA procedure results in a single 'best estimate' prediction, which has been judged to provide engineers with a practical way to assess CIPS risk. As such, however, there is a probability that the actual plant CIPS performance may be underestimated. This paper describes a method to assess the probability (with an associated confidence level) of no CIPS, mild to moderate CIPS, or severe CIPS using BOA for a given core design. This is accomplished through the use of a Monte Carlo simulation. The simulation is applied to several plant examples, and the results are evaluated in terms of the likelihood of mild or severe CIPS. A suggested set of criteria for decision making regarding CIPS risk is presented in the conclusion. (authors)

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗
DOE OSTI2019

Unique reactivity of B in B[Ge 9 Y 3 ] 3 (Y = H, CH 3 , BO, CN): formation of a Lewis base

Boron compounds usually exhibit Lewis acidity at the boron center due to the presence of vacant p-orbitals. We show that this chemistry can be altered by an appropriate choice of ligands to decorate the boron center. To elucidate this effect, we studied the interactions of boron with two classes of ligands, one based on penta-substituted phenyl species (C 6 X 5 , X = F, BO, CN) and the other based on Zintl-ion-based groups (Ge 9 Y 3 , Y = H, CH 3 , BO, CN). An in-depth analysis of the charges and Fukui function values at the local atomic sites of the substituted boron derivatives B(C 6 X 5 ) 3 and B[Ge 9 Y 3 ] 3 shows that the B-center in the former is electrophilic, while it is nucleophilic in the latter. The chemical stability of the B[Ge 9 Y 3 ] 3 species is shown to be due to the presence of strong 2c-2e bonds between the B and Ge centers. Thus, the general notion of the Lewis acid nature of a boron center depends upon the choice of the ligand.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2016

The Effectiveness of Gd Contents of Fuel Basket Wall in UNF Shipping and Storage Cask - 16598

A more effective basket structure, which employs the single wall basket structure and more effective neutron absorbing materials compared to the conventional 3 wall structure with boron neutron absorber, is under development. The criticality of the cask was evaluated as a function of the Gd and B contents in the plate and the Gd-containing SS plate thickness while maintaining the basic geometry the same as the reference cask which uses boron compound as neutron absorber. The KENO-VI code in SCALE with the data library ENDF/B-VII 238-group was used. In all the range of interest, the k{sub eff} values are below 0.4 which is much lower than licensing limit of 0.95. As Gd content increases, the k{sub eff} exponentially decreases. The Gd added SS shows higher performance than B added case in low atomic percent region. The B case curve showed less steep slope than the Gd case. The results of the wall thickness effect calculation indicated that the k{sub eff} decreases with thickness increase until ∼6 mm and it increases as thickness increases over ∼7 mm. (authors)

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗
DOE OSTI2016

A New Light Weight Structural Material for Nuclear Structures

Radiation shielding materials are commonly used in nuclear facilities to attenuate the background ionization radiations to a minimum level for creating a safer workplace, meeting regulatory requirements and maintaining high quality performance. The conventional radiation shielding materials have a number of drawbacks: heavy concrete contains a high amount of elements that are not desirable for an effective shielding such as oxygen, silicon, and calcium; a well known limitation of lead is its low machinability and toxicity, which is causing a major environmental concern. Therefore, an effective and environmentally friendly shielding material with increased attenuation and low mass density is desirable. Close-cell composite metal foams (CMFs) and open-cell Al foam with fillers are light-weight candidate materials that we have studied in this project. Close-cell CMFs possess several suitable properties that are unattainable by conventional radiation shielding materials such as low density and high strength for structural applications, high surface area to volume ratio for excellent thermal isolation with an extraordinary energy absorption capability. Open-cell foam is made up of a network of interconnected solid struts, which allows gas or fluid media to pass through it. This unique structure provided a further motive to investigate its application as radiation shields by infiltrating original empty pores with high hydrogen or boron compounds, which are well known for their excellent neutron shielding capability. The resulting open-cell foam with fillers will not only exhibit light weight and high specific surface area, but also possess excellent radiation shielding capability and good processability. In this study, all the foams were investigated for their radiation shielding efficiency in terms of X-ray, gamma ray and neutron. X-ray transmission measurements were carried out on a high-resolution microcomputed tomography (microCT) system. Gamma-emitting sources: 3.0mCi 60 Co, 1.8mCi 137 Cs, 13.5mCi 241 Am, and 5.0mCi 133 Ba were used for gamma-ray attenuation analysis. The evaluations of neutron transmission measurements were conducted at the Neutron Powder Diffractometer beam facility at North Carolina State University. The experimental results were verified theoretically through XCOM and Monte Carlo Z-particle Transport Code (MCNP). A mechanical investigation was performed by means of quasi-static compressive testing. Thermal characterizations were carried out through effective thermal conductivity and thermal expansion analyses in terms of high temperature guarded-comparative-longitudinal heat flow technique and thermomechanical analyzer (TMA), respectively. The experimental results were compared with analytical results obtained from, respectively, Brailsford and Major’s model and modified Turner’s model for verification. Flame test was performed in accordance with United States Nuclear Regulatory Commission (USNRC) standard. CMF sample and a 304L stainless steel control sample were subjected to a fully engulfing fire with an average flame temperature of 800°C for a period of 30 minutes. Finite Element Analysis was conducted to secure the credibility of the experimental results. This research indicates the potential of utilizing the light-weight close-cell CMFs and open-cell Al foam with fillers as shielding material replacing current heavy structures with additional advantage of high-energy absorption and excellent thermal characteristics.

36 MATERIALS SCIENCE↗
DOE OSTI2021

Spontaneous dynamical disordering of borophenes in MgB2 and related metal borides

Abstract Layered boron compounds have attracted significant interest in applications from energy storage to electronic materials to device applications, owing in part to a diversity of surface properties tied to specific arrangements of boron atoms. Here we report the energy landscape for surface atomic configurations of MgB 2 by combining first-principles calculations, global optimization, material synthesis and characterization. We demonstrate that contrary to previous assumptions, multiple disordered reconstructions are thermodynamically preferred and kinetically accessible within exposed B surfaces in MgB 2 and other layered metal diborides at low boron chemical potentials. Such a dynamic environment and intrinsic disordering of the B surface atoms present new opportunities to realize a diverse set of 2D boron structures. We validated the predicted surface disorder by characterizing exfoliated boron-terminated MgB 2 nanosheets. We further discuss application-relevant implications, with a particular view towards understanding the impact of boron surface heterogeneity on hydrogen storage performance.

36 MATERIALS SCIENCE↗
DOE OSTI2016

Modulating the spin transport behaviors in ZBNCNRs by edge hydrogenation and position of BN chain

Using the density functional theory and the nonequilibrium Green’s function method, we study the spin transport behaviors in zigzag boron-nitrogen-carbon nanoribbons (ZBNCNRs) by modulating the edge hydrogenation and the position of B-N nanoribbons (BNNRs) chain. The different edge hydrogenations of the ZBNCNRs and the different position relationships of the BNNRs have been considered systematically. Our results show that the metallic, semimetallic and semiconductive properties of the ZBNCNRs can be modulated by the different edge hydrogenations and different position relationships of BN chains. And our proposaled ZBNCNRs devices act as perfect spin-filters with nearly 100% spin polarization. These effects would have potential applications for boron-nitrogen-carbon-based nanomaterials in spintronics nano-devices.

77 NANOSCIENCE AND NANOTECHNOLOGY↗
DOE OSTI2016

Development of Cement Solidification Technique for Sodium Borate Waste Produced in PWR Plants - 16061

A cement solidification process for treating sodium borate waste produced in pressurized water reactor (PWR) plants was studied. It is known that the setting and hardening reaction of cement is retarded by the presence of boron compounds. This technique was developed to obtain high uniaxial compressive strength more than 10 MPa which can satisfy various countries disposal regulations. As examples of disposal regulations, France requires 8 MPa for homogeneous solidified products. The sodium/ boron (Na/B) ratio was controlled to about 1 by adding NaOH to simulated liquid waste for the purpose of improving the workablility and mechanical strength. To obtain high volume reduction, simulated liquid waste was dehydrated and powdered by using a wiped film evaporator. Ordinary portland cement (OPC) was used for the solidification. The viscosity of cement mixture was controlled by the water/cement ratio. The resulting viscosity became less than 25 dPa.s, and it was possible to continuously mix the mixture. Solidified cement with containing 73 kg/m{sup 3} of boron had a uniaxial compressive strength of more than 10 MPa. (authors)

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2016

Submicron R{sub 2}Fe{sub 14}B particles

Mechanochemical synthesis of submicron R{sub 2}Fe{sub 14}B particles with R = Dy, Nd, Pr has been performed successfully via high energy ball milling of rare-earth oxides, iron oxide and boron oxide in the presence of a reducing agent (Ca) and a dispersant material (CaO), followed by annealing at 800 - 900 °C. In the R = Nd system, we were able to fabricate particles embedded in a CaO matrix with coercivity (H{sub c}) of 10.3 kOe after annealing at 900 °C for 5 min. After washing off the dispersant, the H{sub c} was decreased to below 1 kOe because of hydrogen absorption that leads to the formation of the hydrated R{sub 2}Fe{sub 14}BH{sub x} phase that has a lower anisotropy. Upon removal of the hydrogen the coercivity was increased to 3.3 kOe. The average size of the Nd{sub 2}Fe{sub 14}B particles increases from 100 nm in a sample synthesized at 800 °C to 158 nm at 900 °C. The isotropic Dy{sub 2}Fe{sub 14}B particles showed a higher coercivity of 21 kOe in washed samples after annealing at 900 °C for 5 min. An average size of 71 nm is measured in samples synthesized at 800 °C and 107 nm at 900 °C. Fitting the high field M(H) measurements in Nd{sub 2}Fe{sub 14}B to the law of approach to saturation gave values for the magnetocrystalline anisotropy for the washed sample 2.23 × 10{sup 7} erg/cm{sup 3} and for the vacuum annealed sample 4.15 × 10{sup 7} erg/cm{sup 3}, both of which are lower than the bulk values. This would explain the lower values of H{sub c} observed in the particles.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2017

Validation and Comparison of the Therapeutic Efficacy of Boron Neutron Capture Therapy Mediated By Boron-Rich Liposomes in Multiple Murine Tumor Models

Boron neutron capture therapy (BNCT) was performed at the University of Missouri Research Reactor in mice bearing CT26 colon carcinoma flank tumors and the results were compared with previously performed studies with mice bearing EMT6 breast cancer flank tumors. We implanted mice with CT26 tumors subcutaneously in the caudal flank and were given two separate tail vein injections of unilamellar liposomes composed of cholesterol, 1,2-distearoyl-sn-glycer-3-phosphocholine, and K[nido-7-CH 3 (CH 2 ) 15 –7,8-C 2 B 9 H 11 ] in the lipid bilayer and encapsulated Na 3 [1-(2`-B 10 H 9 )-2-NH 3 B 10 H 8 ] within the liposomal core. Mice were irradiated 30 hours after the second injection in a thermal neutron beam for various lengths of time. The tumor size was monitored daily for 72 days. In spite of relatively lower tumor boron concentrations, as compared to EMT6 tumors, a 45 minute neutron irradiation BNCT resulted in complete resolution of the tumors in 50% of treated mice, 50% of which never recurred. Median time to tumor volume tripling was 38 days in BNCT treated mice, 17 days in neutron-irradiated mice given no boron compounds, and 4 days in untreated controls. Tumor response in mice with CT26 colon carcinoma was markedly more pronounced than in previous reports of mice with EMT6 tumors, a difference which increased with dose. The slope of the dose response curve of CT26 colon carcinoma tumors is 1.05 times tumor growth delay per Gy compared to 0.09 times tumor growth delay per Gy for EMT6 tumors, indicating that inherent radiosensitivity of tumors plays a role in boron neutron capture therapy and should be considered in the development of clinical applications of BNCT in animals and man.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2017

“Ni{sub 5}TiO{sub 7}” is Ni{sub 5}TiO{sub 4}(BO{sub 3}){sub 2}

It is shown that the compound known as Ni{sub 5}TiO{sub 7} and considered as a promising catalyst and oxidation product of alloys does not exist and its XRD pattern actually corresponds to Ni{sub 5}TiO{sub 4}(BO{sub 3}){sub 2} - Graphical abstract: XRD pattern of “Ni{sub 5}TiO{sub 7}” (top) is identical to that for Ni{sub 5}TiO{sub 4}(BO{sub 3}){sub 2} (bottom) based on single-crystal structural data. - Highlights: • Popular catalyst known as Ni{sub 5}TiO{sub 7} is actually Ni{sub 5}TiO{sub 4}(BO{sub 3}){sub 2}. • B{sub 2}O{sub 3} came from the flux used for crystal growth. • Some authors reporting this phase did not use any boron compounds.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2019

A Tunable Optimized Low-Temperature Sensor Based on the Hybrid Photonic Crystals (F{sub 4}/Bg{sub 5}/F{sub 4}) and (Bg{sub 5}/F{sub 4}/Bg{sub 5})

In this paper, we present a novel type of low-temperature sensor based precisely on the symmetrical hybrid photonic crystals. Thanks to the two-fluid model and the transfer matrix method, we study the temperature sensitivity of the hybrid multilayers (F{sub 4}/Bg{sub 5}/F{sub 4}) and (Bg{sub 5}/F{sub 4}/Bg{sub 5}) where F{sub 4} represents the fourth iteration of the quasi-periodic Fibonacci sequence and Bg5 designates the multilayer Bragg mirror (HLS){sub 5}. We assume that the layers H, L, and S indicate precisely the dielectric materials of Bi{sub 4}Ge{sub 3}O{sub 12}, SiO{sub 2}, and YaBO{sub 2}CuO{sub 7} superconductor one. The analysis of the transmittance spectra shows that the hybrid photonic crystal is more sensitive to the temperature than the periodic one. A higher sensibility value is reached due to the possible combination of the periodic and quasi-periodic sequences. Our investigation reveals that the photonic crystal (F{sub 4}/Bg{sub 5}/F{sub 4}) is more sensitive to low temperature compared to (Bg{sub 5}/F{sub 4}/Bg{sub 5}). The sensitivity is significantly affected by the position of quasi-periodic sequences. The sensitivity of such photonic crystals can be adequately controlled by applying a symmetrical chirping. The designed structures pave the way toward the achievement of a potential low-temperature sensor.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗