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GRADIENT AND LAYERED BORON NITRIDE FORMATION UNDER EFFECT OF CONCENTRATED LIGHT IN A FLOW OF NITROGEN
Abstract
Results of the effect of concentrated light energy in a xenon high-flux optical furnace on transformation of boron nitride (BN) and boron (B) powders in a flow of nitrogen are presented. Raman, Auger Electron (AES), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), scanning and transmission electron microscopes (SEM and TEM), the measurement of band gap using transmittance technique have been employed for investigation of the properties of produced nanostructures. According Raman, AES and FTIR study the surface of all prepared nanopowders is composed of BN. XRD disclosed pure amorphous boron inside particle. Gradient transformation pure boron to BN in the framework of one particle as well as layered nanostructure was observedby TEM study. Dependence of a square of the optical absorption coefficient for a deposited BN film versus the photon energy of incident light has confirmedagradient and layered nature of the prepared BN nanostructures.
... The initial powders of h-BN and B (particle size ~ 0.2 μm) and metallic In at a ratio of 3:1 were chosen as an object for investigation. Detail description of origin powders and experimental were presented in a number of papers [12][13][14][15][16][17] . Heating the surface of compacted samples was carried out in a xenon high-flux optical furnace in a flow of nitrogen at the density of energy 0,3 -0,7 10 4 kW/m 2 . ...
... Probability of presence of the main components are given in a Table 1. Based on the great difference in melting points of In and B, our experience [13][14][15][17][18][19][20] and results in 21 , 22 it can be concluded that resulting powder consists of much more In and B components. The microstructure of powder was characterized by SEM analysis to understand the process of new structure formation during heat treatment of compacted sample (B -25 wt.% In). ...
... On a surface of the compacted sample beside a reaction zone was found fullerene-like and a few one-dimensional structures (Fig. 5a), which look like InN obtained from In2O3 30 . The release of gaseous impurities causes the appearance of holes (Fig. 5b) and one-dimensional structures formation ( Fig. 5a), according to the "gaseous model" for nanotube formation and growth presented in 14,18 . This fact was confirmed direct observation nanocage growth by molecular beam nitriding and liquid-like motion of Fe-B nanoparticles 31 . ...
Transformation of BN and B powders and 25 wt.% In in a high-flux optical furnace in flow of nitrogen was considered. Powders were collected at different distances from a reaction zone. In nanopowder with a thin oxidised layer was formed during heating BN and In at 1000°C. Heating at 1500°C s results in platelike and equiaxed BN particles, compose B inside and H3BO3 layer, nano-petal particles, compose InN and number of fullerene-like particles with complicated ‘core shell’ structure. The last was formed as a result of segregation of transparent shell of B components around crystalline fullerene-like InN. These structures arise from a bubbles evolution of B and In components in conformity with ‘gaseous model for nanotubes and fullerenes formation and growth’. InN prevents the formation of new modifications of BN and shifting stretching band of BN according to FTIR. BN disclosed itself as an excellent getter for InN.
KEYWORD: Concentrated light heating; BN; InN; ‘core shell’ structure; phase composition; FTIR spectroscopy
Results of the effect of concentrated light energy in a xenon high-flux optical furnace on transformation of boron nitride (BN) and boron (B) powders in a flow of nitrogen are presented. Raman, Auger Electron (AES), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), scanning and transmission electron microscopes (SEM and TEM), the measurement of band gap using transmittance technique have been employed for investigation of the properties of produced nanostructures. According Raman, AES and FTIR study the surface of all prepared nanopowders is composed of BN. XRD disclosed pure amorphous boron inside particle. Gradient transformation pure boron to BN in the framework of one particle as well as layered nanostructure was observed by TEM study. Dependence of a square of the optical absorption coefficient for a deposited BN film versus the photon energy of incident light has confirmed a gradient and layered nature of the prepared BN nanostructures.
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