scholarly journals High-Yield Synthesis of Cubic and Hexagonal Boron Nitride Nanoparticles by Laser Chemical Vapor Decomposition of Borazine

2013 ◽  
Vol 2013 ◽  
pp. 1-5 ◽  
Author(s):  
A. Hidalgo ◽  
V. Makarov ◽  
G. Morell ◽  
B. R. Weiner
Keyword(s):  
Electron Microscopy ◽  
Boron Nitride ◽  
Hexagonal Boron Nitride ◽  
Chemical Vapor ◽  
High Yield ◽  
X Ray Diffraction ◽  
Transmission Electron ◽  
Chemical Vapor Decomposition ◽  
Electron Energy Loss ◽  
Bn Nanostructures

We report a new method for the synthesis of boron nitride nanostructures (nBN) using laser chemical vapor decomposition (LCVD). Borazine was used as precursor and excited with two simultaneous radiations, the fundamental and second YAG laser harmonics. If only one of the two radiations is employed, no reaction takes place. Abundant BN powder is obtained after one hour of laser radiation. The BN yield obtained with the LCVD technique is about 83% by weight. The BN material was characterized using scanning electron microscopy, transmission electron microscopy, electron energy loss spectroscopy, Raman spectroscopy, Fourier transform infrared spectroscopy, and X-ray diffraction. They all indicate that the BN powder consists of a mixture of hexagonal and cubic BN nanostructures. No other BN phases or stoichiometries were found. The size of the resulting BN nanostructures is in the range of 20–100 nm and their B : N composition is 1 : 1. A simplified mechanism involving laser-excited states followed by photoinduced removal of hydrogen is proposed to understand the synthesis of BN nanopowder by LCVD of borazine.

scholarly journals Catalyst-Free Bottom-Up Synthesis of Few-Layer Hexagonal Boron Nitride Nanosheets

2015 ◽  
Vol 2015 ◽  
pp. 1-8 ◽  
Author(s):  
Shena M. Stanley ◽  
Amartya Chakrabarti ◽  
Joshua J. DeMuth ◽  
Vanessa E. Tempel ◽  
Narayan S. Hosmane
Keyword(s):  
Electron Microscopy ◽  
Boron Nitride ◽  
Hexagonal Boron Nitride ◽  
X Ray Diffraction ◽  
Bottom Up ◽  
X Ray ◽  
Boron Nitride Nanosheets ◽  
Catalyst Free ◽  
Transmission Electron ◽  
Novel Catalyst

A novel catalyst-free methodology has been developed to prepare few-layer hexagonal boron nitride nanosheets using a bottom-up process. Scanning electron microscopy and transmission electron microscopy (both high and low resolution) exhibit evidence of less than ten layers of nanosheets with uniform dimension. X-ray diffraction pattern and other additional characterization techniques prove crystallinity and purity of the product.

scholarly journals Synthesis of Three-Dimensionally Interconnected Hexagonal Boron Nitride Networked Cu-Ni Composite

2021 ◽  
Vol 59 (7) ◽  
pp. 505-513
Author(s):  
Zahid Hussain ◽  
Hye-Won Yang ◽  
Byung-Sang Choi
Keyword(s):  
Electron Microscopy ◽  
Boron Nitride ◽  
Hexagonal Boron Nitride ◽  
Compaction Pressure ◽  
Chemical Properties ◽  
Chemical Vapor ◽  
Organic Chemical ◽  
Transmission Electron ◽  
Ni Alloy ◽  
Composite Energy

A three-dimensionally interconnected hexagonal boron nitride (3Di-hBN) networked Cu-Ni (3DihBN-Cu-Ni) composite was successfully synthesized in situ using a simple two-step process which involved the compaction of mixed Cu-Ni powders (70 wt.% Cu and 30 wt.% Ni) into a disc followed by metal-organic chemical vapor deposition (MOCVD) at 1000 oC. During MOCVD, the Cu-Ni alloy grains acted as a template for the growth of hexagonal boron nitride (hBN) while decaborane and ammonia were used as precursors for boron and nitrogen, respectively. Boron and nitrogen atoms diffused into the Cu-Ni solution during the MOCVD process and precipitated out along the Cu-Ni interfaces upon cooling, resulting in the formation of the 3Di hBN-Cu-Ni composite. Energy-dispersive spectroscopic analysis confirmed the presence of boron and nitrogen atoms at the interfaces of Cu-Ni alloy grains. Optical microscopy examination indicated that there was a minimum amount of bulk hBN at a certain compaction pressure (280 MPa) and sintering time (30 min). Scanning electron microscopy and transmission electron microscopy revealed that an interconnected network of hBN layers surrounding the Cu-Ni grains developed in the 3Di-hBN-Cu-Ni composite. This 3Di-hBN network is expected to enhance the mechanical, thermal, and chemical properties of the 3Di-hBN-Cu-Ni composite. Moreover, the foam-like 3Di-hBN extracted from 3Di-hBN-Cu-Ni composite could have further applications in the fields of biomedicine and energy storage.

scholarly journals Получение гетерогенных наночастиц Al/BN в микроволновой плазме

2020 ◽  
Vol 46 (10) ◽  
pp. 25
Author(s):  
Ш. Корте ◽  
М.К. Кутжанов ◽  
А.М. Ковальский ◽  
А.С. Конопацкий ◽  
Д.Г. Квашнин ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Boron Nitride ◽  
Microwave Plasma ◽  
Hexagonal Boron Nitride ◽  
Shear Stresses ◽  
X Ray Diffraction ◽  
Short Term ◽  
X Ray ◽  
Transmission Electron

In this work, the interaction of a mixture of Al and BN nanopowder with hydrogen microwave plasma was studied. Using X-ray diffraction analysis, scanning and transmission electron microscopy, the formation of AlN and AlB2 nanocrystals as a result of short-term (~ 30 ms) interaction of Al vapor with h-BN was established. Obtained results also indicate the formation of hydrogenated hexagonal boron nitride h-BN-H. The critical shear stresses were calculated for the interfaces between BN and Al, AlB2, and AlN. Approaches for increasing the strength of the composite materials based on hexagonal boron nitride and aluminum are discussed.

Thickness and Rotational Effects in Simulated HRTEM Images of Graphene on Hexagonal Boron Nitride

2014 ◽  
Vol 20 (6) ◽  
pp. 1753-1763
Author(s):  
Avery J. Green ◽  
Alain C. Diebold
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Boron Nitride ◽  
Hexagonal Boron Nitride ◽  
Substrate Thickness ◽  
Epitaxial Relationship ◽  
Transmission Electron ◽  
Electron Energy Loss ◽  
Simulated Images ◽  
Multilayer Stacks

AbstractRecent studies have shown that when graphene is placed on a thin hexagonal boron nitride (h-BN) substrate, unlike when it is placed on a typical SiO2 surface, it can closely approach the ideal carrier mobility observed in suspended graphene samples. This study further examines the epitaxial relationship between graphene and h-BN substrate with high-resolution transmission electron microscopy simulation. Virtual monolayer and multilayer stacks of h-BN were produced with a monolayer of graphene on top, on bottom, and in between h-BN layers, in order to study this interface. Once the simulations were performed, the phase contrast image and Moiré pattern created by this heterostack were analyzed for local and global intensity minima and maxima. In addition, h-BN substrate thickness and rotations between h-BN and graphene were probed and analyzed. The simulated images produced in this work will be used to help understand subsequent transmission electron microscopy images and electron energy-loss studies.

Laser Deposited Cubic Boron Nitride Films

1990 ◽  
Vol 191 ◽  
Author(s):  
Gary L. Doll ◽  
Jeffrey A. Sell ◽  
Lourdes Salamanca-riba ◽  
Ashwin K. Ballal
Keyword(s):  
Electron Microscopy ◽  
Boron Nitride ◽  
Hexagonal Boron Nitride ◽  
Cubic Boron Nitride ◽  
Emission Spectra ◽  
Optical Emission ◽  
Film Deposition ◽  
X Ray Diffraction ◽  
Transmission Electron ◽  
Boron Nitride Films

ABSTRACTWe report the successful growth of cubic boron nitride thin films on single crystal 100 silicon by using pulsed excimer laser ablation of a hexagonal boron nitride bulk target. Optical emission spectra were obtained during the film deposition giving insight into the deposition mechanism. The deposited films were characterized by transmission electron microscopy, scanning electron microscopy, optical microscopy, x-ray diffraction, and Auger electron microscopy. Regions of the films were found to exhibit epitaxy with the substrate.

Low Temperature Large Scale CVD Synthesis of Nano Onion-Like Fullerenes

2012 ◽  
Vol 490-495 ◽  
pp. 3211-3214 ◽  
Author(s):  
Lei Shan Chen ◽  
Cun Jing Wang
Keyword(s):  
Electron Microscopy ◽  
Low Temperature ◽  
Aluminum Hydroxide ◽  
Large Scale ◽  
Iron Catalyst ◽  
Chemical Vapor ◽  
X Ray Diffraction ◽  
Transmission Electron ◽  
Naoh Solution ◽  
Synthesis Reactions

Synthesis reactions were carried out by chemical vapor deposition using iron catalyst supported on aluminum hydroxide at 400 °C and 420 °C, in the presence of argon as carrier gas and acetylene as carbon source. The aluminum hydroxide support was separated by refluxing the samples in 40% NaOH solution for 2 h and 36% HCl solution for 24 h, respectively. The samples were characterized by field-emission scanning electron microscopy, energy dispersive spectroscopy, high-resolution transmission electron microscopy and X-ray diffraction. The results show that carbon nanotubes were the main products at 420 °C, while large scale high purity nano onion-like fullerenes encapsulating Fe3C, with almost uniform sizes ranging from 10-50 nm, were obtained at the low temperature of 400 °C.

scholarly journals Fabrication and Physical Properties of Single-Crystalline Βeta-FeSi2 Nanowires

2020 ◽  
Vol 15 (1) ◽  
Author(s):  
Chih-Yung Yang ◽  
Shu-Meng Yang ◽  
Yu-Yang Chen ◽  
Kuo-Chang Lu
Keyword(s):  
Electron Microscopy ◽  
Physical Properties ◽  
Chemical Vapor ◽  
Chemical Vapor Deposition Method ◽  
Ferromagnetic Behavior ◽  
X Ray Diffraction ◽  
Field Emitters ◽  
Transmission Electron ◽  
Single Source Precursor ◽  
Carrier Gases

Abstract In this study, self-catalyzed β-FeSi2 nanowires, having been wanted but seldom achieved in a furnace, were synthesized via chemical vapor deposition method where the fabrication of β-FeSi2 nanowires occurred on Si (100) substrates through the decomposition of the single-source precursor of anhydrous FeCl3 powders at 750–950 °C. We carefully varied temperatures, duration time, and the flow rates of carrier gases to control and investigate the growth of the nanowires. The morphology of the β-FeSi2 nanowires was observed with scanning electron microscopy (SEM), while the structure of them was analyzed with X-ray diffraction (XRD) and transmission electron microscopy (TEM). The growth mechanism has been proposed and the physical properties of the iron disilicide nanowires were measured as well. In terms of the magnetization of β-FeSi2, nanowires were found to be different from bulk and thin film; additionally, longer β-FeSi2 nanowires possessed better magnetic properties, showing the room-temperature ferromagnetic behavior. Field emission measurements demonstrate that β-FeSi2 nanowires can be applied in field emitters.

Control of Morphology and Growth Direction of Gallium Nitride Nanostructures

2003 ◽  
Vol 789 ◽  
Author(s):  
Seung Yong Bae ◽  
Hee Won Seo ◽  
Jeunghee Park
Keyword(s):  
Electron Microscopy ◽  
Gallium Nitride ◽  
Large Scale ◽  
Chemical Vapor ◽  
Growth Direction ◽  
Chemical Vapor Deposition Method ◽  
X Ray Diffraction ◽  
Oxide Mixture ◽  
Temperature Range ◽  
Transmission Electron

ABSTRACTVarious shaped single-crystalline gallium nitride (GaN) nanostructures were produced by chemical vapor deposition method in the temperature range of 900–1200 °C. Scanning electron microscopy, transmission electron microscopy, electron diffraction, x-ray diffraction, electron energy loss spectroscopy, Raman spectroscopy, and photoluminescence were used to investigate the structural and optical properties of the GaN nanostructures. We controlled the GaN nanostructures by the catalyst and temperature. The cylindrical and triangular shaped nanowires were synthesized using iron and gold nanoparticles as catalysts, respectively, in the temperature range of 900 – 1000 °C. We synthesized the nanobelts, nanosaws, and porous nanowires using gallium source/ boron oxide mixture. When the temperature of source was 1100 °C, the nanobelts having a triangle tip were grown. At the temperature higher up to 1200 °C the nanosaws and porous nanowires were formed with a large scale. The cylindrical nanowires have random growth direction, while the triangular nanowires have uniform growth direction [010]. The growth direction of the nanobelts is perpendicular to the [010]. Interestingly, the nanosaws and porous nanowires exhibit the same growth direction [011]. The shift of Raman, XRD, and PL bands from those of bulk was correlated with the strains of the GaN nanostructures.

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