10043-11-5Relevant articles and documents
A room-temperature approach to boron nitride hollow spheres
Chen, Luyang,Gu, Yunle,Shi, Liang,Yang, Zeheng,Ma, Jianhua,Qian, Yitai
, p. 537 - 540 (2004)
Boron nitride hollow spheres were synthesized by the reaction of BBr 3 and NaNH2 at room temperature; X-ray powder diffraction pattern could be indexed as hexagonal BN with the lattice constants of a=2.482 and c=6.701?; high-resolution transmission electron microscopy image showed the hollow spheres consisted of BN nanoparticles, with diameter between 80 and 300 nm; a possible formation mechanism of BN hollow spheres was discussed.
One pot synthesis of ultrathin boron nitride nanosheet-supported nanoscale zerovalent iron for rapid debromination of polybrominated diphenyl ethers
Wang, Liancheng,Ni, Shou-Qing,Guo, Chunli,Qian, Yitai
, p. 6379 - 6387 (2013)
To minimize the aggregation and size effects of nanoscale zerovalent iron (nZVI), nZVI/boron nitride nanosheets (BNNSs) composites were fabricated via a one pot autoclave route on a gram-scale. BNNSs (1-6 nm) supported nZVI (4-40 nm) was prepared by heating NaBH4, FeCl3 and NaN3 at 400 °C. The BNNSs matrixes benefit the retention of the activity for nZVI. The high specific surface area (182 m2 g -1) and density of structural defects allows enrichment of the pollutants, leading to a relatively high conversion by the nearby supported nZVI. Meanwhile, the gram-scale bifunctional nZVI/BNNSs have both reductive and magnetic properties, which make them highly reactive towards the test polybromodiphenyl ethers (PBDEs) and also easy to separate. The reaction rate of nZVI/BNNSs is almost twice that of the nZVI made in our lab. This study indicates that gram-scale nZVI/BNNSs are highly efficient and effective materials that can be utilized to treat PBDEs-contaminated sites, followed by the sequential magnetic separation. The Royal Society of Chemistry 2013.
New Phase of sp3-Bonded BN: The 5H Polytype
Komatsu, Shojiro,Okada, Katsuyuki,Shimizu, Yoshiki,Moriyoshi, Yusuke
, p. 3289 - 3291 (1999)
A new phase of sp3-bonded BN, that is, 5H polytype, has been found. The representative lattice parameters a and c were determined to be 2.528 and 10.407 Angstroem, respectively. The new BN phase was prepared by chemical vapor deposition assisted with 193 nm laser irradiation of the surface. Source gases were diborane and ammonia diluted in argon and hydrogen. The substrate temperature was 850 degC.
Characterization of boron nitride films deposited from BCl3-NH3-H2 mixtures in chemical vapour infiltration conditions
Cholet, V.,Vandenbulcke, L.,Rouan, J. P.,Baillif, P.,Erre, R.
, (1994)
Boron nitride (BN) thin films deposited by isopressure and isothermal chemical vapour infiltration (ICVI) from BCl3-NH3-N2 mixtures have been characterized from a physicochemical point of view as functions of both the deposition conditions and the destabilizing action of moisture. As-deposited (deposited at 773 K and post-treated at 1273 K), the BN films are turbostractic (d002 = 0.36 nm, Lc = 1.5 nm), have a low density (1.4 g cm-3) and contain oxygen (about 20 at%). A first oxygen content (191.5 eV by XPS) is inserted in the films during the CVI step in relation to the hygroscopy of intermediate solid products and the quasi-equilibrium between the formation of BN and B2O3. A second oxygen content (192.5 eV) is due to the hydrolysis of BN by moisture which induces a very drastic transformation of BN. This destabilization affects both boron and nitrogen atoms and leads to the formation of ammonium borate hydrates. Different post-treatments have been investigated to stabilize the BN films and it appears that nitriding under ammonia is the most efficient.
A low-temperature coreduction route to boron nitride flakes and hollow spheres
Chen, Luyang,Gu, Yunle,Shi, Liang,Yang, Zeheng,Ma, Jianhua,Qian, Yitai
, p. 144 - 145 (2004)
Boron nitride flakes and hollow spheres were synthesized by coreduction of NH4Cl and BBr3 using sodium as reductant. X-ray powder diffraction (XRD) pattern could be indexed as hexagonal BN. The X-ray photoelectron spectra (XPS) were used to determine the composition ratio, which is B:N = 1:1.05. The transmission electron microscopy (TEM) images showed flake-like and hollow spherical morphology.
Large-scale fabrication of boron nitride nanohorn
Zhi, Chunyi,Bando, Yoshio,Tang, Chengchun,Golberg, Dmitri,Xie, Rongguo,Sekiguchi, Takashi
, (2005)
Boron nitride nanohorns (BNNHs) are synthesized in large scale. Their morphology and structure were investigated by scanning electron microscopy and transmission electron microscopy. The hollow conical structure and particular aggregation behavior are rev
Boron nitride microfibers grown by plasma-assisted laser chemical vapor deposition without a metal catalyst
Komatsu, Shojiro,Kazami, Daisuke,Tanaka, Hironori,Shimizu, Yoshiki,Moriyoshi, Yusuke,Shiratani, Masaharu,Okada, Katsuyuki
, (2006)
Boron nitride fibers were found to grow on polycrystalline nickel and Si(100) substrates by plasma-assisted laser chemical vapor deposition from B2 H6 + NH3 using an excimer laser at 193 nm. Their diameter was typically a few hundreds of nanometers, while the length was a few tens of micrometers. They were stoichiometric or boron-rich BN in chemical composition. When the substrate was rotated during deposition, spiral fibers were found to grow. We conclude that they grew with the help of laser light by other than the vapor - liquid - solid mechanism.
Band gap and chemically ordered domain structure of a graphene analogue BxCyNz
Venu,Kanuri,Raidongia,Hembram,Waghmare,Datta
, p. 2262 - 2265 (2010)
Chemically synthesized few layer graphene analogues of BxC yNz are characterized by aberration corrected transmission electron microscopy and high resolution electron energy loss spectroscopy (HREELS) to determine the local phase, electronic structure and band gap. HREELS band gap studies of a BxCyNz composition reveal absorption edges at 2.08, 3.43 and 6.01 eV, indicating that the B xCyNz structure may consist of domains of different compositions. The K-absorption edge energy position of the individual elements in BxCyNz is determined and compared with h-BN and graphite. An understanding of these experimental findings is developed with complementary first-principles based calculations of the various ordered configurations of BxCyNz.
Catalytic synthesis of bamboo-like multiwall BN nanotubes via SHS-annealing process
Zhang,Gu,Wang,Zhao,Qian,Li,Pan,Zhang
, p. 633 - 636 (2011)
Bamboo-like multiwall boron nitride (BN) nanotubes were synthesized via annealing porous precursor prepared by self-propagation high temperature synthesis (SHS) method. The as-synthesized BN nanotubes were characterized by the field emission scanning elec
Electronic and optical properties of boron nitride nanotubes
Oku, Takeo,Koi, Naruhiro,Suganuma, Katsuaki
, p. 1228 - 1231 (2008)
Boron nitride (BN) nanotubes were fabricated, and their electronic and optical properties were investigated by scanning tunneling microscopy (STM) and optical absorption at room temperature. STM images showed atomic arrangements of BN nanotubes, and its chirality was directly observed. The current-voltage characteristics of the BN nanotubes showed onset voltage at 5.0 V, and the optical absorption spectrum of BN nanotubes showed a peak at 4.8 eV.
Formation, structure, and structural properties of a new filamentary tubular form: Hollow conical-helix of graphitic boron nitride
Xu, Fang-Fang,Bando, Yoshio,Ma, Renzhi,Golberg, Dmitri,Li, Yubao,Mitome, Masanori
, p. 8032 - 8038 (2003)
A novel tubular form of graphitic boron nitride (BN) displaying a hollow conical-helix was discovered. It was generated via wrapping a single beltlike filament according to the geometry of an Archimedes spiral. Cone apex angles of helical-conical nanotubes (HCNTs) were found to exhibit specific values, each of which refers to a certain coincidence site lattice. A unique structural property of HCNTs was observed, displaying the transformation of apex angles during the annealing process. The observed apex angles were reduced with decreasing annealing temperature, which is in accordance with an estimated HCNT strain energy decrease for a given tubular radius. It is suggested that the curvature and apex angle of a HCNT are determined by a sole dynamic element, that is, enthalpy (ΔH), whereas the HCNT disclination configuration changes through helical sliding of the filament.
Synthesis of nitrogen-rich B-C-N materials from melamine and boron trichloride
Popov, Cyril,Saito, Kimitsugu,Yamamoto, Kazuhiro,Ouchi, Akihiko,Nakamura, Takako,Ohana, Yoritsugu,Koga, Yoshinori
, p. 1281 - 1286 (1998)
Nitrogen-rich B C N materials have been prepared by the reaction between melamine and boron trichloride at different temperatures. The composition of the materials was dependent on the synthesis and annealing temperatures: C6N10.8-11H9.4B1.5-1.7 (for products synthesized and annealed at 673 K), C6N9.3-9.4H3.8-3.9B2.2-2.5 (for those synthesized at 673 K and annealed at 873 K) and C6N9.2H3.6B1.2-1.3 (for those synthesized and annealed at 873 K). Fourier transform infrared spectroscopy and 13C nuclear magnetic resonance showed that the s-triazine rings from the melamine molecules were preserved in materials synthesized and annealed at 673 and 873 K. The sample obtained at 873 K had a graphite-like structure as suggested by X-ray and electron diffraction studies. The s-triazine rings were decomposed in the materials synthesized or annealed at 1223 K and the main product obtained was turbostratic boron nitride.
Over 1.0 mm-long boron nitride nanotubes
Chen, Hua,Chen, Ying,Liu, Yun,Fu, Lan,Huang, Cheng,Llewellyn, David
, p. 130 - 133 (2008)
Over 1.0 mm boron nitride nanotubes (BNNTs) were successfully synthesized by an optimized ball milling and annealing method. The annealing temperature of 1100 °C is crucial for the growth of the long BNNTs because at this temperature there is a fast nitrogen dissolution rate in Fe and the B/N ratio in Fe is 1. Such long BNNTs enable a reliable single tube configuration for electrical property characterization and consequently the average resistivity of the long BNNTs is determined to be 7.1 ± 0.9 × 104 Ω cm. Therefore, these BNNTs are promising insulators for three dimensional microelectromechanical system.
Turbostratic boron nitride coated on high-surface area metal oxide templates
Klitgaard, Soren K.,Egeblad, Kresten,Brorson, Michael,Herbst, Konrad,Christensen, Claus H.
, p. 4873 - 4876 (2007)
Boron nitride coatings on high-surface area MgAl2O4 and Al2O3 have been synthesized and characterized by transmission electron microscopy and by X-ray powder diffraction. The metal oxide templates were coated with boron nitride using a simple nitridation in a flow of ammonia starting from ammonium borate adsorbed on MgAl2O 4 or γ-Al2O3. This procedure resulted in the formation of a turbostratic boron nitride film with a thickness of a few individual BN layers. Wiley-VCH Verlag GmbH & Co. KGaA, 2007.
Attempts of boron nitride deposition on different substrates under the influence of the electric field present in the reaction zone
Pawlas-Foryst, Ewa,Przybylo, Witold,Kopyto, Marek,Fitzner, Krzysztof
, p. 915 - 923 (2001)
Attempts were undertaken to obtain deposits of hexagonal boron nitride under the influence of either the electric field or current of various frequency flowing through the substrate. It was demonstrated that magnetic field as well as electrical potential difference created in the reaction zone both influence the way BN layers are formed. The layers grow with the formation of fine crystallites in the center of the substrate with their size increasing while moving from the center of the substrate to its edges. Distinct correlation between the electric fields line density and the sizes of the crystallites was observed. The distribution of the crystallites depends on current frequency used. It was found that there is an optimal current frequency for which the substrate is covered with the homogeneous layer of BN. The adhesion of this deposit depends strongly on the kind of the substrate used.
Phase identification of boron nitride thin films by polarized infrared reflection spectroscopy
Plass,Fukarek,Maendl,Moeller
, p. 46 - 48 (1996)
Six different types of boron nitride films were investigated by polarized infrared reflection spectroscopy. Films with a highly cubic, mixed cubic and noncubic, and exclusively noncubic phase composition were synthesized using ion beam assisted deposition. Additionally, postdeposition argon ion irradiated cubic and noncubic boron nitride films as well as a nitrogen implanted boron sample were analyzed. Using this technique, besides the cubic phase, two different noncubic modifications, layered anisotropic and amorphous, could be distinguished. A preferential orientation of the normal axis of the sp2-bonded basal planes parallel to the substrate surface was observed.
Influence of Diborane Flow Rate on the Structure and Stability of CVD Boron Nitride Films
Gomez-Aleixandre, C.,Essafti, A.,Fernandez, M.,Fierro, J. L. G.,Albella, J. M.
, p. 2148 - 2153 (1996)
CVD boron nitride films have been deposited at 800 deg C from diborane, ammonia, and hydrogen gas mixtures, using different B2H6 flow rates.The effect of the / ratio in the gas mixture on the structure, composition, and the stability of the lay
Structure of boron nitride nanoscale cones: Ordered stacking of 240° and 300° disclinations
Bourgeois,Bando,Han,Sato
, p. 7686 - 7691 (2000)
Recently discovered boron nitride (BN) nanoscale cone particles are shown to consist of an ordered stacking of seamless conical shells. High-resolution transmission electron microscopy and nanobeam electron diffraction allowed the orientation of the BN hexagonal rings to be determined. In all but one case, the results conformed with a model of orderly stacked 240° disclinations, which is the smallest cone geometry ensuring the presence of B-N bonds only. One case of a nanoscale cone constituted of 300° disclinations was found, implying that structures containing line defects of non-B-N bonds may form. 2000 The American Physical Society.
Syntheses of metal nitrides, metal carbides and rare-earth metal dioxymonocarbodiimides from metal oxides and dicyandiamide
Lei,Zhao,Yang,Song,Cao,Li,Tang
, p. 130 - 137 (2008)
We design a facile and efficient solid-state reaction method by selecting an organic reagent dicyandiamide and metal oxides as precursors to prepare metal nitrides, carbides and rare-earth metal dioxymonocarbodiimides in sealed ampoules. Some fine divided nitride and carbide nanoparticles with small and uniform size can be easily obtained at the relatively low temperatures. It is interesting to find that dicyandiamide is not only a highly efficient nitridation reagent but also a highly efficient carburization reagent, and can be used as a precursor to directly synthesize rare-earth metal dioxymonocarbodiimides. A possible mechanism is proposed to explain the results of the reactions between the organic reagent and metal oxides.
DENSITY AND DEPOSITION RATE OF CHEMICAL-VAPOUR-DEPOSITED BORON NITRIDE.
Matsuda, Toshitsugu,Nakae, Hiroyuki,Hirai, Toshio
, (1988)
A study was made on the density and deposition rate characteristics of chemical vapour deposited boron nitride (CVD-BN) plates synthesized by use of the BCl//3-NH//3-H//2 system at a deposition temperature (T//d//e//p) of 1200 to 2000 degree C and a total gas pressure (P//t//o//t) of 5 to 60 torr. At a P//t//o//t of 5 torr, all the CVD-BN plates synthesized at each T//d//e//p above 1300 degree C had a density greater than 2. 0 g cm** minus **3 and showed no noticeable dependence on T//d//e//p. Over the P//t//o//t range from 10 to 60 torr, the density reached a maximum of 2. 08 g cm** minus **3 at a T//d//e//p of 2000 degree C. As T//d//e//p was lowered, density decreased to a minimum of 1. 40 g cm** minus **3. The deposition rate varied with both T//d//e//p and P//t//o//t and showed a maximum value under a certain P//t//o//t at a given T//d//e//p. The value of P//t//o//t where the deposition rate becomes maximum changed depending on the T//d//e//p. The maximum deposition rate was 0. 6 mm h** minus **1 for the CVD-BN plates when the density was less than 2. 0 g cm** minus **3 and 0. 4 mm h** minus **1 when the density was above 2. 0 g cm** minus **3. The effects of deposition conditions on the characteristics of density and deposition rate are discussed in terms of the structure and deposition mechanism.
Influence of isothermal chemical vapor deposition and chemical vapor infiltration conditions on the deposition kinetics and structure of boron nitride
Leparoux, Marc,Vandenbulcke, Lionel,Clinard, Christian
, p. 1187 - 1195 (1999)
An experimental study has been performed to gain some insight into the correlations between the deposition conditions and the structure of boron nitride (BN) coatings that are used in ceramic-matrix composites. BN has been deposited at 700°C from BCl3-NH3-H2 mixtures on various substrates, by using chemical vapor deposition (CVD) and isothermal-isobaric chemical vapor infiltration (ICVI) processes, simultaneously in the same reactor. A kinetic study has shown that the CVD process is governed either by a combination of mass transfer with chemical kinetics at low flow rates or by the heterogeneous kinetics only at high flow velocities. In contrast, the limiting contribution of mass transfer always is observed for the ICVI process. The influence of diffusion cages that are positioned around the fibrous preforms is reported. The structure of BN deposits has been studied as a function of the various deposition conditions via transmission electron microscopy. The chosen CVD conditions lead to a poor organization of the BN deposits. Fairly well-organized BN coatings are deposited on all fibers of a fibrous preform via ICVI. The results are discussed in terms of supersaturation and deposition yields. The use of diffusion cages and the adjustment of the inlet composition and mass flow rate seem to be very important to obtain the best BN organization and thickness uniformity.
Formation and atomic structure of boron nitride nanotubes with a cup-stacked structure
Oku, Takeo,Koi, Naruhiro,Suganuma, Katsuaki,Belosludov, Rodion V.,Kawazoe, Yoshiyuki
, p. 331 - 336 (2007)
Boron nitride (BN) nanotubes were synthesized by annealing Fe4N/B powder at 1000?{ring operator}C for 1 h in a nitrogen gas atmosphere, and large amounts of BN nanotubes with a cup-stacked structure were obtained after a purification process. The atomic structures of the cup-stacked BN nanotubes were investigated by high-resolution electron microscopy as well as molecular mechanics calculations, and compared with double walled BN nanotubes. The present results indicate that the cup-stacked structure with a cone angle of 20{ring operator} is more stable than the structure with an angle of 38{ring operator} and ordinary nanotube structures.
Conversion of dihydridodiammineboron(III) borohydride to ammonia-borane without hydrogen evolution
Mayer, Erwin
, p. 1954 - 1955 (1973)
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Purification of boron nitride nanotubes
Chen, Hua,Chen, Ying,Yu, Jun,Williams, James S.
, p. 315 - 319 (2006)
A purification process was developed for the first time for boron nitride (BN) nanotubes. BN nanotubes, prepared using a ball milling and annealing method, contain a high yield of nanotubes and a small amount of BN and metal catalyst particles. The metal particles can be dissolved in an HCl solution. Fine BN nanoparticles and thin layers were first converted to water soluble B2O3 via a partial oxidation treatment at 800 °C. The oxide particles and layers can then be dissolved in hot water. Thermogravimetric analysis has been used to determine an adequate oxidation temperature at which fine BN particles were oxidized.
Synthesis and structure of BN coatings on SiC nanofibers
Silenko,Shlapak,Pilipchuk,D'Yachkov,Solonin
, p. 1330 - 1333 (2011)
The Gibbs potential has been calculated as a function of temperature for a number of BN synthesis reactions. Detailed studies of BN chemical vapor deposition on SiC nanofibers were used to develop a technique for BN coating production from nontoxic precur
Cu-Catalyzed Chemoselective Reduction of N-Heteroaromatics with NH3·BH3 in Aqueous Solution
Gao, Chao,Xuan, Qingqing,Song, Qiuling
supporting information, p. 2504 - 2508 (2021/07/31)
An efficient catalytic system was successfully developed on reduction of N-heteroaromatics with H3N?BH3 as hydrogen source in CuSO4 solution, featuring excellent chemoselectivity as well as very broad functional group tolerance. Various challenging substrates, such as OH-, NH2-, Cl-, Br-, etc., contained quinolines, quinoxalines, 1,5-naphthyridines and quinazolines were all reduced smoothly. Mechanistic studies suggested that [Cu-H] intermediate might be generated from NH3?BH3, which was believed to form with H3N?BH3 in CuSO4 solution.
Boron-hyperdoped silicon for the selective oxidative dehydrogenation of propane to propylene
Chen, Junjie,Karakalos, Stavros G.,Kyriakidou, Eleni A.,Lance, Michael J.,Rohani, Parham,Swihart, Mark T.,Toops, Todd J.
supporting information, p. 9882 - 9885 (2020/09/09)
Boron containing catalysts have great potential in the oxidative dehydrogenation of propane. Herein, a series of 15, 25 and 42 atpercent boron-hyperdoped silicon catalysts synthesized by laser pyrolysis was studied. Boron-hyperdoped silicon samples showed >6 times higher propylene productivity than commercial h-BN at 450 °C.
OPEN-FLASK HYDROBORATION AND THE USE THEREOF
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Paragraph 0042, (2018/03/25)
The present disclosure generally relates to a process for hydroboration of an alkene or alkyne using ammonia borane (AB). In particular, the present invention relates to hydroboration of an alkene or alkyne in the presence of air or moisture, and a clean process for facile preparation of an alcohol by oxidizing the organoborane so formed with hydrogen peroxide. The products, including aminodialkylboranes, ammonia trialkylborane complexes, as well as various alcohols so prepared, are within the scope of this disclosure.
