Synthèse
Volume 5, Numéro 1, Pages 23-27
1999-06-30
Interfacial Properties Of Liquid Alloys :an Experimental Study On Ga-bi And Ga-ge
Authors : Chadli H. . Boufelfel A. .
Abstract
Interfacial phase like wetting and prewetting transitions arc of considerable interest in physics and chemistry of condensed matter since the represent phase transition is reduced dimensionality. Besides this, interfacial properties are of profound practical and technological interest. Most systems studied experimentally in this respect are characterized by Van der Waals intermolecular interactions. However, in the last few years is shown that Coulomb liquids like liquid alloys or metal molten saIt solutions exhibit interfacial phase transition similar to those known in Van der Waals systems .. In order to get more insight into these phenomena the fluid-vapor interface of two different alloy systems have been studied using ellipsometry. Ga-Bi is binary ally, with large positive deviations from Raoult's law, exhibiting a distinct miscibility gap. Approaching liquid-liquid coexistence a bi-rich film completely wets the fluid-vapor interface. As can be estimated from ellipsometric results the film thickness jumps, at the monotectic temperature to a value of about 50 A. In contrast, Ga-Ge shows continuous miscibility and deviates much less from ideal mixing. As the Ge concentration in liquid Ga increases along the solid-liquid coexistence curve the optical properties at the surface also vary continuously, which can be modeled within a simple effective medium approach.
Keywords
pas de mots clés
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