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Proceedings Paper

Initial stages of crystallization of transitional metals oxides under laser-light influence
Author(s): L. M. Kriukova; O. V. Leontyeva
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Paper Abstract

The investigations of laser light interaction with a matter are of increased interest now because of the development and wide industrial applications of laser technique. Such processes as defects formation, diffusion, solid state chemical reactions and others may be initiated under the laser light influence. That, the growth of "huge" crystals on the surface of copper target irradiated by the carbon dioxide laser light has been detected by authors I1I. An anomalous mass transport of impurities induced by the laser light action has been observed in a number of materials. Thus, the penetration of carbon into titanium under the pulse laser light exposure (A = 1.06 411111, T =iO s, E=1O -120 J) and introduction of boron into steel patterns induced by a continuous carbon dioxide laser light have been investigated, and the penetration depths of impurities were found to exceed considerably those of radiation /2,3/. The intensive redistribution of the impurities is clearly determined by the phase transition proceeding. In work /4/, an unusual 5-6 orders increasing in the coefficient of interstitial impurities diffusion into V205 and an acceleration of the solid state reactions caused by resonance CO2 laser light have been demonstrated. Besides, the works on the diffusion stimulated by short wavelength radiation (2=44mm and .=66Onm, N - 1 /cm2) / 1 ,5/ are of profound interest now. In these experiments, the heat was supposed to be no more than 1K. Incidentally, the possible statement about the defects formation as a result of photo stimulation was considered to be improbable as requiring the high energy values (I < iO W/cm2) . Intense pulsed laser influence, which flux density exceeds the threshold value, causes the formation of the layers with a great number of nonstationary defects and is accompanied by high rate of the crystallization front movement (—lOm/s) /6,7/. Similar phenomena have been studied under the action of other types of high energy flux. For example, a perceptible acceleration of the phase formation induced by the electron beam with energy level of l2OkeV, crystallization and recrystallization /9/ , an anomalous transport of the interstitial impurities in both the metals and the transitional metals oxides / 10/ have been registered. It should be noted that all the phenomena considered are accompanied by abrupt grain growth and, consequently, by crystallization and recrystallization. The phenomena observed can not be explained with a heat model limit. The clear explanation for this phenomena is not accepted now, but one may suppose that the laser light induced weak nonstationarity in condensed matter changes substantially the processes behavior if the system state corresponds to the critical points of the equilibrium diagram. Such a situation may be realized, for example, during the chemical reactions and phase transformations. The transitional metals oxides (V205, Nb205, MoO3) were chosen as objects under examination, and the explanation for this choice lies in the possibility to form nonstationary defects states under the different types of laser influence.

Paper Details

Date Published: 24 June 1993
PDF: 7 pages
Proc. SPIE 1856, Laser Radiation Photophysics, (24 June 1993); doi: 10.1117/12.147620
Show Author Affiliations
L. M. Kriukova, Moscow Institute of Steels and Alloys (Russia)
O. V. Leontyeva, Moscow Institute of Steels and Alloys (Russia)

Published in SPIE Proceedings Vol. 1856:
Laser Radiation Photophysics
Bodil Braren; Mikhail N. Libenson, Editor(s)

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