%0 Journal Article
%T Size Effects on Surface Elastic Waves in a Semi-Infinite Medium with Atomic Defect Generation
%A F. Mirzade
%J Advances in Condensed Matter Physics
%D 2013
%I Hindawi Publishing Corporation
%R 10.1155/2013/528208
%X The paper investigates small-scale effects on the Rayleigh-type surface wave propagation in an isotopic elastic half-space upon laser irradiation. Based on Eringen¡¯s theory of nonlocal continuum mechanics, the basic equations of wave motion and laser-induced atomic defect dynamics are derived. Dispersion equation that governs the Rayleigh surface waves in the considered medium is derived and analyzed. Explicit expressions for phase velocity and attenuation (amplification) coefficients which characterize surface waves are obtained. It is shown that if the generation rate is above the critical value, due to concentration-elastic instability, nanometer sized ordered concentration-strain structures on the surface or volume of solids arise. The spatial scale of these structures is proportional to the characteristic length of defect-atom interaction and increases with the increase of the temperature of the medium. The critical value of the pump parameter is directly proportional to recombination rate and inversely proportional to deformational potentials of defects. 1. Introduction During the last decades elastic wave propagation in solids (metals and semiconductors) with nonequilibrium atomic defects has received a lot of attention [1¨C4]. Various types of lattice defects (vacancies and interstitials), produced from the lattice site atoms due to intense external energy fluxes (laser and corpuscular radiations), introduce a significant strain of the medium as a result of the difference between the radii of lattice atoms and defects [5] and play an important role in surface modification of solids exposed to laser radiation [1, 5, 6]. The formation of atomic defects may occur also in a number of other technologies processes: in the laser fast recrystallization, laser annealing, multipulse laser etching, pulsed laser-assisted thin-film deposition, and so forth. Strains in an elastic wave cause a strain-induced drift of defects, whereas the strains and a variation in the temperature in the wave modulate the rates of generation and recombination of defects of the thermal-fluctuation origin (via variations in the energies of the defect formation and migration) [5, 6]. Several mathematical models have been considered to study the self-organization of two-dimensional (2D) ordered microscale concentration-strain (CS) structures (at high concentrations of atomic defects) on the surface of the solid half-space [7, 8] and in an isotropic solid elastic layer [9, 10] under the action of laser irradiation. In these studies, attention was also focused on the study of an
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