Abstract: The aim of this study was to produce an infrared transmitting material with multiphonon absorption edge longer than 20μm.
For this purpose, chalcohalide glasses based on As₂Se₃-AsTe-CuI system were studied. The glass forming region was obtained and
homogeneous glass prepared. Binary system glass may be formed by combining As₂Se₃ with AsTe in any proportion, the maximum content
of CuI in As₂Se₃ is up to 70 mol% and that of CuI in AsTe about 45 mol%. These glasses have a good glass forming ability and it is easy
to obtain the samples of diameter about 20mm and thickness over 50mm. The far infrared spectra of the glasses were investigated. The results
demonstrate that basic structural units are [As(SeTe)_3-xI_x(x=0～3), As₂Te₄] and [CuI_4], their proportions depend on the
composition of the glasses. With the help of experimental results and theoretical analysis, a structural model of glasses was suggested.

Key words: chalcohalide glass, glass forming, glass structure, infrared transmitting materials