The decisive role of oxide content in the formation and crystallization of gallium-lanthanum-sulfide glasses
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The decisive role of oxide content in the formation and crystallization of gallium-lanthanum-sulfide glasses Ruihua Li, David Furniss, Heath Bagshaw, and Angela B. Seddon Centre for Glass Research, Department of Engineering Materials, The University of Sheffield, Sheffield, S1 3JD, United Kingdom (Received 6 July 1998; accepted 16 February 1999)
A series of gallium-lanthanum-sulfide (GLS) glasses of different oxide concentration has been made and their spectroscopic properties, thermal properties, and the crystallization behavior of the glasses have been studied. It was revealed that the formability of GLS glasses relies on the existence of a certain amount of oxide content. The thermal stability of GLS glasses changes as a function of oxide concentration. The results have also shown that increasing oxide content caused a shift of the visible absorption edge to shorter wavelengths and an increase of absorption intensity in the infrared region at the multiphonon edge. Two closely related crystalline phases have been identified in the crystallized GLS glasses. For the first time it has been revealed that thermally stable GLS glasses can be made near the eutectic point of these two crystal phases by introducing an optimized amount of oxide.
I. INTRODUCTION 1,2
In the 1970s, Loireau-Lozac’h et al. established that Ga2 S3 –La2 S3 is a glass-forming system. Rare-earthdoped gallium-lanthanum-sulfide (GLS) glasses have been proposed as potential hosts for 1.3 mm optical fiber amplifiers and for fiber lasers in the near- and midinfrared.3–5 Much effort has been expended to develop low-loss GLS glass fiber but no usable active fiber devices have been made yet, mainly due to the difficulty of making low-loss, monomode fibers. A comprehensive study of glass formation and crystallization behavior has been necessary to obtain a better understanding of this glass-forming system, and to move toward the manufacture of low-loss infrared transmitting optical fibers. The current study has focused on the effects of oxide content on the formation and crystallization of GLS glasses. A series of GLS glasses containing different levels of oxide was made and the effects of oxide content on the glass-forming ability, spectroscopic properties, thermal properties, and crystallization behavior have been studied. II. EXPERIMENTAL PROCEDURES A. Glass preparation
Ten glass compositions, shown in Table I, were prepared. They are coded as glass no. 1 to no. 10 in order of increase of “oxygen” content in their composition. All chemicals used were supplied by Merck Limited, U.K. The precursors Ga2 S3 and La2 S3 used for glasses no. 1 to no. 3 contained 0.12 and 0.14 wt% “oxygen” (as fO22 g), respectively, while the Ga2 S3 and La2 S3 used for glasses no. 4 to no. 10 contained 0.10 and 1.07 wt% “oxygen,” respectively. The “oxygen” content of the J. Mater. Res., Vol. 14, No. 6, Jun 1999
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precursors was measured by means of LECO analysis by the Supplie
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