CC BY
10LM-O-15
LASER-MATTER INTERACTION
Laser assisted synthesis of boron nanoparticles
K.O. Aiyyzhy, E.V. Barmina, G.A. Shafeev
Prokhorov General Physics Institute of the Russian Academy of Sciences, Vavilova str. 38, 119991 Moscow, Russia
Recently, there has been a great interest in the preparation of elemental boron nanoparticles (NP's). Boron is superior to hydrocarbons in terms of volumetric heat of combustion and in terms of specific mass heat of combustion [1]. These qualities, along with the low toxicity of boron nanoparticles and the possibility of their industrial production, make it possible to consider suspensions of boron nanoparticles in hydrocarbons as promising energy-intensive composite fuels. Studies show that the use of boron nanoparticles as an additive in composite fuel gives a significant increase in temperature in the combustion flame, which affects the energy intensity of the fuel [2, 3]. The burning rate is proportional to the specific surface area of the particles, therefore for efficient combustion the size of the nanoparticles should be as small as possible. Also a decrease size of boron particle lead to an increase in the efficiency of combustion and an expansion of the ignition limits. Industrial powders of Boron are submicron in size. Thus, the aim of this work was to obtain boron nanoparticles with sizes less than 100 nm.
Nanoparticles of elemental Boron are generated by laser ablation of a sintered Boron target in liquid isopropanol and subsequent laser fragmentation of the suspension. For this purpose an ytterbium doped fiber laser with an average power of 20 W, wavelength of 1060-1070 nm, pulse repetition rate of 20 kHz, and pulse duration of 200 ns was used. The size of Boron nanoparticles after ablation and fragmentation of the suspension is around 5-50 nm with maximum of size distribution at 12 nm. Nanoparticles are made mostly of Boron and carbon, some particles have graphitized carbon shell. Crystallographic planes of the shell are visible in Fig. 1. The planes are also projected on the central part of the particle. Their estimated period is 0.34 nm that corresponds to graphitized Carbon. Allotropic composition of nanoparticles differs from that of the initial Boron target. Results of combustion process of hydrocarbon fuels with the addition of Boron NP's showed that during ignition of the composite fuel the temperature in the flame front region increases compared with that in the flame of pure isopropanol.
Fig. 1. TEM view of individual Boron nanoparticle
[1] G. Young, K. Sullivan, M. R. Zachariah, K. Yu, Combustion characteristics of boron nanoparticles, Combustion and Flame, vol 156, pp. 322-333, (2009).
[2] S. Karmakar, S. Acharya, K. M. Dooley, Ignition and Combustion of Boron Nanoparticles in Ethanol Spray Flame, Journal of Propulsion and Power, vol. 28, pp. 707-718, (2013).
[3] E.V. Barmina, M.I. Zhilnikova, K.O. Aiyyzhy, V.D. Kobtsev, D.N. Kozlov, S.A. Kostritsa, S.N. Orlov, A.M. Saveliev, VV. Smirnov, N.S. Titova, G.A. Shafeev, Experimental investigation of diffuse burning of suspension of Boron nanoparticles in isopropanol, Doklady Physics, vol. 67 No. 2, pp. 39-43, (2022).
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