Crystalline Silicon under Acoustic Cavitation: From Mechanoluminescence to Amorphization

Abstract

The physicochemical behavior of crystalline silicon under acoustic cavitation is investigated in water sparged with argon at low temperature (10 and 20 °C). Surprisingly, spectroscopic investigations reveal that argon (bubbling continuously through the liquid phase during experiments) can be ultrasonically excited via mechanoluminescence, i.e., emission of light caused by mechanical action on a solid. This phenomenon is highlighted for the first time on an extended solid surface using these conditions and results from an interaction between the acoustically generated bubbles and the Si surface. The concomitant physical and chemical transformations induced at the solid–liquid interface are investigated (SEM, AFM) to characterize the generated stress and defects in combination with the roughness and wettability increases (evolving from ∼46° to ∼4°). Phase transformations of the Si lattice are observed (Raman spectroscopy, TEM) evidencing the complex stress state induced by acoustic cavitation in the Si crystal structure. The mechanisms involved during Si sonication are discussed.

Sonochemical redox reactions of Pu(iii) and Pu(iv) in aqueous nitric solutions

“…14,37,38 At collapse, concerted microjets and shock waves provoke the erosion of surfaces. This effect results from the implosive collapse of acoustic bubbles in the vicinity of extended solid surfaces.…”

Interplay Between Mechanochemistry and Sonochemistry

“…More complex transformations have been observed for crystalline silicon under acoustic cavitation in water sparged with Ar at temperatures of between 10 and 20 ºC [137]. Spectroscopic investigation reveals that Ar, which is bubbled continuously through the liquid phase, is ultrasonically excited via mechanoluminescence, i.e.…”

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