STRUCTURE OF THE AMORPHOUS T1SEX SYSTEM

Samples of bulk amorphous material were prepared in the range from TlSe2 to Se. Analysis of radial electron density distribution curves of samples TlSe2, TlSe2.7, TlSe9 and Se indicates that selenium rings and/or chains are responsible for the existence of the amorphous phase in a relatively broad interval of compositions. Increasing the Tl content we observe in the first stage (for TlSe9) that Tl atoms are embedded either ionically or in isolated Tl[Se4] tetrahedrons between Se-rings and/or chains. Further increasing the Tl content (for TlSe2.7 and TlSe2) chains of Tl[Se4]-tetrahedra (probably edge-bound) are formed on behalf of selenium rings and/or chains. When a critical amount of these tetrahedra is reached crystallization processes hinder the formation of the amorphous phase. © 1979.