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Results for “BORON COMPOUNDS”

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↗
NASA NTRS1978

Work function measurement of lanthanum-boron compounds

The relationship between emission properties and sample composition is studied for lanthanum-boron compounds. Specifically, the La-B system is considered between 1400 and 2100 K and between LaB(4.24) and LaB(29.2) to determine the phase relationship, chemical activity of the compounds, vapor composition, and vaporization rate. The results indicate that: (1) a blue-colored phase near LaB(9) exists between a purple-colored LaB(6) and elemental boron, (2) vaporization is sufficiently more rapid than diffusion so that great compositional differences exist between the surface and the interior, (3) an activation energy lowers the boron vaporization rate from LaB(6), and (4) a steady-state surface composition between LaB(6.04) and LaB(6.07) exists for freely vaporizing materials as a function of interior composition, purity, and temperature. It is noted that the ultimate life of a thermionic diode is governed by electrode vaporization rate whereas efficiency is governed by the electrode work function.

Jacobson, D. L.↗
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↗
NASA NTRS1988

Feasibility studies of the growth of 3-5 compounds of boron by MOCVD

Boron-arsenic and boron-phosphorus films have been grown on Si sapphire and silicon-on-sapphire (SOS) by pyrolyzing Group 3 alkyls of boron, i.e., trimethylborane (TMB) and triethylborane (TEB), in the presence of AsH3 and PH3, respectively, in an H2 atmosphere. No evidence for reaction between the alkyls and the hydrides on mixing at room temperature was found. However, the films were predominantly amorphous. The film growth rate was found to depend on the concentration of alkyl boron compound and was essentially constant when TEB and AsH3 were pyrolyzed over the temperature range 550 C to 900 C. The films were found to contain mainly carbon impurities (the amount varying with growth temperature), some oxygen, and were highly stressed and bowed on Si substrates, with some crazing evident in thin (2 micron) B-P and thick (5 micron) B-As films. The carbon level was generally higher in films grown using TEB as the boron source. Films grown from PH3 and TMB showed a higher carbon content than those grown from AsH3 and TMB. Based on their B/As and B/P ratios, films with nominal compositions B sub12-16 As2 and B sub1.1-1.3 P were grown using TMB as the boron source.

Manasevit, H. M.↗
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↗
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 NTRS1989

The use of metalorganics in the preparation of semiconductor materials. VIII - Feasibility studies of the growth of Group III-Group V compounds of boron by MOCVD

The MOCVD growth of B-As and B-P films on Si, sapphire, and Si-on-sapphire substrates is described; in this process, trimethylborane (TMB) or triethylborane (TEB) is pyrolyzed in the presence of AsH3 or PH3 in an H2 atmosphere. The procedures employed are outlined, and the results are presented in graphs, tables, and micrographs. It is found that the growth rate of the primarily amorphous films is dependent on the TMB or TEB concentration but approximately constant for TEB and AsH3 at 550-900 C. The nominal compositions of films grown using TMB are given as B(12-16)As2 and B(1-1.3)P. Carbon impurities and significant stress, bowing, and crazing are observed in the films grown on Si substrates, with the highest carbon content in the films grown from TMB and PH3.

Manasevit, H. M.↗
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↗