The quaternary Ga-Ge-Sb-Se system has been systematically studied and the g
lass-forming region has been determined. It has been found that there is a
domain in which glasses do not crystallise when heated at a rate of 10 degr
ees C/min. Optical properties of these glasses have been determined, showin
g transmission from 0.9 to 15 mu m. The refractive index for the Ga5Sb10Ge2
5Se60 glass is 2.6709 +/- 0.0001 at 2 mu m and 2.6198 +/- 0.00025 at 12 mu
m. Some attempts have been made to increase the band-gap by introducing 5-3
0 wt% of electronegative elements such as Cl-2, Br-2 or I-2 in the form of
alkaline halides. Refractive indices, optical transmission and chemical dur
ability towards air and hot water of these new glasses have been measured.
Results have been obtained with CsI addition and stable red coloured glasse
s have been synthesised, which are transparent to 14 mu m. (C) 1999 Publish
ed by Elsevier Science B.V. All rights reserved.