Explosion Phase Formation of Nanocrystalline Boron Nitrides Upon Pulsed-Laser-Induced Liquid/Solid Interfacial Reaction

2003 ◽  
Vol 18 (12) ◽  
pp. 2774-2778 ◽  
Author(s):  
J.B. Wang ◽  
X.L. Zhong ◽  
C.Y. Zhang ◽  
B.Q. Huang ◽  
G.W. Yang

Boron nitride (BN) nanocrystals with explosion (E) phase were prepared by a novel laser-assisted materials fabrication, i.e., pulsed-laser-induced liquid (acetone)/solid (hexagonal boron nitride bulk) interfacial reaction at normal temperature and pressure. Typical diameters of these synthesized quasi-spherical BN nanocrystals were in the range of 30 to 80 nm. Transmission electron microscopy, x-ray diffraction, and Fourier transformed infrared spectroscopy were used to identify the morphologies and structures of the synthesized nanocrystals. Additionally, we proposed the formation mechanism of cubic-BN and E-BN nanocrystals upon pulsed-laser-induced liquid/solid interfacial reaction, in which both liquid and solid were simultaneously involved.

2015 ◽  
Vol 2015 ◽  
pp. 1-8 ◽  
Author(s):  
Shena M. Stanley ◽  
Amartya Chakrabarti ◽  
Joshua J. DeMuth ◽  
Vanessa E. Tempel ◽  
Narayan S. Hosmane

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.


Author(s):  
Ш. Корте ◽  
М.К. Кутжанов ◽  
А.М. Ковальский ◽  
А.С. Конопацкий ◽  
Д.Г. Квашнин ◽  
...  

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.


2007 ◽  
Vol 7 (2) ◽  
pp. 530-534 ◽  
Author(s):  
Chunyi Zhi ◽  
Yoshio Bando ◽  
Guozhen Shen ◽  
Chengchun Tang ◽  
Dmitri Golberg

Adopting a wet chemistry method, Au and Fe3O4 nanoparticles were functionalized on boron nitride nanotubes (BNNTs) successfully for the first time. X-ray diffraction pattern and transmission electron microscopy were used to characterize the resultant products. Subsequently, a method was proposed to fabricate heterojunction structures based on the particle-functionalized BNNTs. As a demonstration, BNNT-carbon nanostructure, BNNT-ZnO and BNNT-Ga2O3 junctions were successfully fabricated using the functionalized particles as catalysts.


2011 ◽  
Vol 675-677 ◽  
pp. 131-134
Author(s):  
Yu Xia Cao ◽  
Ling Zhong Du ◽  
Wei Gang Zhang

CaB2O4 was added into hexagonal boron nitride (hBN) to improve the sintering behaviors of hBN. CaB2O4 and hBN were mixed and then pressed into plates. The plates were sintered at 2000°C for 5h under a N2 ambience. The phase compositions with different CaB2O4 contents were examined with X-ray diffraction analysis. The fracture cross-sections of the hBN plates were investigated by SEM. The apparent density and Rockwell hardness were also measured. The results show that the hBN particles had a plate-like shape and the grain sizes of hBN increased with increasing CaB2O4 contents. The apparent density and Rockwell hardness decreased with increasing CaB2O4 contents. When the CaB2O4 content was 15(wt) %, the hBN has the average grain sizes of 3μm in diameter and 200nm in thickness, the apparent density of 1.06 g/cm3 and the Rockwell hardness of 3, respectively.


2014 ◽  
Vol 936 ◽  
pp. 282-286
Author(s):  
Ying Wen Duan

Single-crystalline, epitaxial LaFeO3 films with 5 at. % substitution of Pd on the Fe site are grown on (100) SrTiO3 substrate by pulsed-laser deposition technique. The epitaxial orientation relationships are (110)[001]LFPO||(100)[001]STO. X-ray diffraction and transmission electron microscopy reveal that the LFPO films have high structural quality and an atomically sharp LFPO/STO interface. After reduction treatments of as-grown LFPO films, very little Pd escaped the LFPO lattice onto the film surface, the formed Pd (100) particles are oriented epitaxially, and parallel to the LFPO films surface.


Author(s):  
Jae-Kap Lee ◽  
Jin-Gyu Kim ◽  
K. P. S. S. Hembram ◽  
Seunggun Yu ◽  
Sang-Gil Lee

Hexagonal boron nitride (h-BN) has been generally interpreted as having an AA stacking sequence. Evidence is presented in this article indicating that typical commercial h-BN platelets (∼10–500 nm in thickness) exhibit stacks of parallel nanosheets (∼10 nm in thickness) predominantly in the AB sequence. The AB-stacked nanosheet occurs as a metastable phase of h-BN resulting from the preferred texture and lateral growth of armchair (110) planes. It appears as an independent nanosheet or unit for h-BN platelets. The analysis is supported by simulation of thin AB films (2–20 layers), which explains the unique X-ray diffraction pattern of h-BN. With this analysis and the role of pressure in commercial high-pressure high-temperature sintering (driving nucleation and parallelizing the in-plane crystalline growth of the nuclei), a growth mechanism is proposed for 2D h-BN (on a substrate) as `substrate-induced 2D growth', where the substrate plays the role of pressure.


1999 ◽  
Vol 14 (6) ◽  
pp. 2355-2358 ◽  
Author(s):  
M. H. Corbett ◽  
G. Catalan ◽  
R. M. Bowman ◽  
J. M. Gregg

Pulsed laser deposition has been used to make two sets of lead magnesium niobate thin films grown on single-crystal h100j MgO substrates. One set was fabricated using a perovskite-rich target while the other used a pyrochlore-rich target. It was found that the growth conditions required to produce almost 100% perovskite Pb(Mg1/3Nb2/3)O3 (PMN) films were largely independent of target crystallography. Films were characterized crystallographically using x-ray diffraction and plan view transmission electron microscopy, chemically using energy dispersive x-ray analysis, and electrically by fabricating a planar thin film capacitor structure and monitoring capacitance as a function of temperature. All characterization techniques indicated that perovskite PMN thin films had been successfully fabricated.


2007 ◽  
Vol 353-358 ◽  
pp. 1505-1508
Author(s):  
Zhi Hua Yang ◽  
Yu Zhou ◽  
De Chang Jia ◽  
Qing Chang Meng ◽  
Chang Qing Yu

Amorphous Si-B-C-N ceramics obtained by high energy ball milling and hot pressing using hexagonal boron nitride (h-BN), graphite (C) and amorphous Si as starting materials have been studied. The mechanical milling with high energy resulted in the generation of large amounts of amorphous composites only milled for 5 h. Si-B-C-N powders were consolidation by hot pressing at 1850 °C. X-ray diffraction (XRD) and transmission electron microscopy (TEM) show that small amount of BN and SiC crystal lies in the amorphous matrix. The flexural strength reached the maximal value of 137.2 MPa at a mole ratio of BN/(Si+C) being 0.6.


2001 ◽  
Vol 16 (9) ◽  
pp. 2467-2470 ◽  
Author(s):  
J. C. Caylor ◽  
M. S. Sander ◽  
A. M. Stacy ◽  
J. S. Harper ◽  
R. Gronsky ◽  
...  

Heteroepitaxial growth of the cubic skutterudite phase CoSb3 on (001) InSb substrates was achieved by pulsed laser deposition using a substrate temperature of 270 °C and a bulk CoSb3 target with 0.75 at.% excess Sb. An InSb (a0 = 4 0.6478 nm) substrate was chosen for its lattice registry with the antimonide skutterudites (e.g., CoSb3 with a = 0 4 0.9034 nm) on the basis of a presumed 45° rotated relationship with the InSb zinc blende structure. X-ray diffraction and transmission electron microscopy confirmed both the structure of the films and their epitaxial relationship: (001)CoSb3 ∥ (001)InSb; [100]CoSb3 ∥ [110]InSb.


1995 ◽  
Vol 410 ◽  
Author(s):  
J. E. Cosgrove ◽  
P. A. Rosenthal ◽  
D. Hamblen ◽  
D. B. Fenner ◽  
C. Yang

ABSTRACTWe have grown thin films of SiC by pulsed laser deposition on silicon (100) and vicinal and non-vicinal 6H SiC (0001) substrates using a quadrupled YAG laser and a high purity dense polycrystalline SiC target. Epitaxy on all three substrate types was confirmed by x-ray diffraction, transmission electron microscopy and electron diffraction. Composition of the films was measured by Rutherford backscattering spectrometry and Scanning Auger Microprobe.


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