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Processes of Formation of AI2O3 and AlN Nanopowders when Exposed to Aluminum by a Series of Double Laser Pulses in Air
Abstract
The effect of the interpulse interval and the number of doubled laser pulses on the targeted formation ofthe component and charge composition of the laser plasma under the influence of doubled laser pulses on a target made of AD1 aluminum alloy (LSS-1 spectrometer) was studied. It is shown that when using he interpulse interval of 7-16 ps, the concentration of Al ions and the products of their interaction with oxygen and nitrogen in the air increases by several orders in comparison with the zero interval. The highest intensity of the bands of AlO suboxide and AlN molecules is observed at 40-50 sequential double pulses in a series. With an increase in the number of pulses in a series the intensity of the bands decreases that is connected with worsening of the interaction of Al atoms and ions with air molecules and atoms at the output from the micro nozzle with a change in the depth and shape of the microchannel. The temperature in the region of the plasma with the maximum content of Al III of ~ 22000-30000 K was estimated. To determine the temperature in the region of AlO formation, the ratio of the intensities of the AlO bands at 486.9/484.12 nm was used. An expression is obtained for determining the temperature of the region corresponding to the maxima of AlO formation. The established temperature range of4700-7000 K is slightly higher than the optimal dissociation temperature for AlO (4400 K). To obtain Al aerosols and products formed during the interaction of aluminum ions with oxygen and nitrogen in the air, a closed glass cell was used, where an aluminum target was placed. The size of the primary particles of aluminum oxide Al2O3 obtained at pulse energy of 53 mJ, estimated using high-resolution electron microscopy, is mainly 30-40 nm. The particles are assembled in agglomerates. The possibility of practical obtaining of activated Al2O3 nanopowders by irradiating the target with successive series of 50 double pulses per point for 10 min in a closed bottle is considered. Using Raman spectroscopy, the possibility of obtaining active forms of aluminum oxides and their interaction products with oxygen and nitrogen of air in a laser plasma, deposited on a glass surface in a closed cell is shown.
For citations:
Bazzal Kh., Alekseenko N.A., Voropay E.S., Kovalenko M.N., Patapovich M.P., Zazhogin А.P. Processes of Formation of AI2O3 and AlN Nanopowders when Exposed to Aluminum by a Series of Double Laser Pulses in Air. Zhurnal Prikladnoii Spektroskopii. 2021;88(2):211-220. (In Russ.)
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