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We present here experimental results on sixty different compositions of the ternary arsenic-tellurium-selenium system. The parameters considered here are: electrical conductivity and its thermal dependence, and transformation temperatures deduced from differential thermal analysis measurements. The synthesis of results leads to the vitrification area for glasses obtained by air quenching and gives rise to an analysis of the influence of the relative concentration of two elements with respect to the third considered as a parameter. DTA studies permit the separation of two different areas in the vitrification surface, corresponding to materials involving or not involving crystallization processes. We have investigated the possible existence of binary or ternary molecular structures in the vitrification region. The results presented here lead to the conclusion that no ternary molecular structure occurs in the AsTeSe system. Nevertheless it seems possible to conclude that one binary molecular structure can be built around As2Se3.

Electrical and DTA measurements have been performed on TeAsGeS glasses. In this group, As 2 Te n Ge (4 ⩽ n ⩽ 7) glasses are of particular interest since, in the AsTeGe vitrigfication diagram, they all are located on a straight line crossing completely one of the two vitrification regions. The comparison of the results of DTA on As 2 Te 3 , Te 4 Ge and As 2 Te n Ge (4 ⩽ n ⩽ 7) shows that the structure of the As 2 Te n Ge glasses is built around the Ge atoms. The electrical properties of a particular family whose composition is near As 2 Te 5 Ge + S as vitrificant agent are given. Photoelectron spectroscopy has also been used for an investigation of the structure of this last family and permits to conclude that in the crystallized state, phase separations occur.