Über Glasbildung und Eigenschaften von Chalkogenidsystemen. XVII. Zur Glaschemie des Germaniumdisulfides

Abstract

Das Glasbildungsverhalten von GeS2 wird durch chemische Fehlordnung in der Schmelze beeinflußt. Für die zur Glasbildung notwendige, hohe Abkühlgeschwindigkeit Rc = 17 K · s−1 sind germaniumreichere Nahordnungsbereiche bestimmend. Durch eine geringe Abweichung von der stöchiometrischen Zusammensetzung nach GeS2,01 kann Rc auf 3 K · s−1 gesenkt werden. Zur Unterdrückung der heterogenen Keimbildung ist eine Destillation der Gläser im Vakuum erforderlich.

Crystallization kinetics of glassy GeS2

“…The analysis below is developed in terms of basic kinetic equation (2) for simple Arrhenius behaviour of the rate constant with respect to temperature during the crystallization process, i.e. Eq.…”

“…The calculation is based on several assumptions. It is presumed that the rate of crystallization can be described by the kinetic equation: (2) where K(T) is a temperature-dependent rate constant in the Arrhenius form;…”

“…Germanium disulphide is a congruently melting (1123 K) semiconducting compound [1] which can be obtained in the glassy state by cooling of the melt at a rate of 17 deg s-1 or higher [2]. Whilethe structure and optical properties of glassy GeS 2 have received great attention [3][4][5], the crystallization of this material has been studied only in some papers.…”

Heterophase inclusions and dissolved impurities in Ge25Sb10S65 glass

“…The possibility of contamination of chalcogenide glasses of systems Ge-Se and Ge-S by SiO 2 micro-inclusions during their melting in quartz glass ampoules was indicated in papers [15,16]. The contamination of Ge-Se melt by flocculent inclusions with size of 10-60 lm in concentration of 500-2000 cm 3 was observed at glass synthesis temperature of 800°C.…”

“…It was assumed that the source of this contamination was the SiO 2 amorphous layer on the inner surface of silica tubes which was removed mechanically by chalcogenide glass melt in the form of inclusions. It was shown in paper [16] that the GeS 2 glass melt lead to corrosion of quartz tube walls with partial dissolution of the surface layer. It was indicated in paper [17] that the etching of quartz glasses in the solution of fluoric acid leads to a 'globular' (cellular) structure of the surface with the size of globules 5-20 l.…”